adapt mat-foundation 2010 manual

[email protected] www.adaptsoft.com

ADAPT Corporation, Redwood City, California, 94061, USA, Tel: +1 (650) 306-2400 Fax +1 (650) 306-2401 ADAPT International Pvt. Ltd, Kolkata, India Tel: +91-33-302 86580 Fax: +91-33-224 67281

STRUCTURAL CONCRETE SOFTWARE

ADAPT-MAT 2010

USER MANUAL

110810

Copyright 2010

LIST OF CONTENTS Content

3

LIST OF CONTENTS

OVERVIEW ...................................................................................................... 5

BASIC FEATURES .......................................................................................... 9 2 OVERVIEW .......................................................................................................... 11 2.1 GEOMETRY ......................................................................................................... 11 2.2 SUPPORT CONDITIONS ..................................................................................... 15

2.2.1 Soil Support Area ....................................................................................... 15 2.2.2 Compression Only Soil .............................................................................. 16 2.2.3 Soil / Rock Anchors ................................................................................... 16 2.2.4 Grade Beam Support .................................................................................. 16 2.2.5 Line Springs ............................................................................................... 17 2.2.6 Point Springs .............................................................................................. 17 2.2.7 Point Supports ............................................................................................ 17 2.2.8 Line Supports ............................................................................................. 17 2.2.9 Piles............................................................................................................ 18 2.2.10 Voids in Soil .............................................................................................. 18

2.3 MATERIAL PROPERTIES................................................................................... 18 2.4 LOADS .................................................................................................................. 18

2.4.1 Load Cases ................................................................................................. 19 2.4.2 Load Combinations .................................................................................... 19

2.5 BASE REINFORCEMENT ................................................................................... 19 2.6 POST-TENSIONING ............................................................................................ 19 2.7 ANALYSIS ............................................................................................................ 20 2.8 DESIGN ................................................................................................................. 21 2.9 GENERATION OF DRAWINGS ......................................................................... 22 2.10 LINK WITH OTHER PROGRAMS AND BUILDER DATA EXCHANGE CAPABILITY

............................................................................................................................ 22

QUICK START ............................................................................................... 23 3 OVERVIEW .......................................................................................................... 25 3.1 OPENING THE PROGRAM ................................................................................. 25 3.2 EXAMPLE 1 .......................................................................................................... 26

3.2.1 Create the Structural Model ....................................................................... 28 3.2.2 Define soil support conditions ................................................................... 29 3.2.3 Validate the Structural Model .................................................................... 29 3.2.4 Complete and Finalize Input Data ............................................................. 29 3.2.5 Perform Analysis ....................................................................................... 29 3.2.6 Prepare to Design ....................................................................................... 30 3.2.7 Validate the Code Compliance of the Design ............................................ 30

Content LIST OF CONTENTS

4

3.2.8 Generate Structural Drawings .................................................................... 31 3.2.9 Generate Structural Calculation Reports ................................................... 31

USER INTERFACE ....................................................................................... 33 4 OVERVIEW .......................................................................................................... 35 4.1 ?? 35 4.2 SOIL PRESSURE .................................................................................................. 35

MODELING AND DESIGN PROCESS ...................................................... 37 5. OVERVIEW .......................................................................................................... 39 5.1 DESIGN PROCEDURE?? .................. ERROR! BOOKMARK NOT DEFINED. 5.2 CONCLUSION OF DESIGN ................................................................................ 46

TUTORIAL ..................................................................................................... 47 6.1 GENERATE STRUCTURAL MODEL ................................................................ 49 6.2 ANALYSIS ............................................................................................................ 49

ANALYTICAL BACKGROUND ................................................................. 89 7 OVERVIEW .......................................................................................................... 91 7.1 STRUCTURAL MODELING ............................................................................... 91 7.2 ANALYSIS ............................................................................................................ 91 7.3 DESIGN ................................................................................................................. 92 7.4 CREATION OF STURCTURAL DOCUMENTS ................................................ 92

EXAMPLES .................................................................................................... 95

SAMPLE CALCULATION REPORT ......................................................... 99 9 OVERVIEW ........................................................................................................ 101

APPENDIX ................................................................................................... 103 NOTATION ......................................................................................................... 105 REFERENCES .................................................................................................... 105

5

Chapter 1

OVERVIEW

OVERVIEW Chapter 1

7

ADAPT MAT is a computer program that enables you to model, analyze, design, and generate structural drawings for ground supported concrete structures that are used to transfer load to the underlain soil in a serviceable and safe manner. The program can handle practically all possible foundation configurations and loads, using a state-of-the-art 3D modeling and Finite Element Technology, and designing in accordance with the US and major international building codes. Following a short glance at some of the features of the program that are described below, it is recommended that you go through the section on “Quick Start” to familiarize yourself with the operation of the program. Next, follow the tutorial, before you start your design project. Since this program forms a part of the ADAPT-Builder suite, the general graphical interface and modeling techniques are described in ADAPT-Floor Pro’s User Manual. This User Manual forms part of the ADAPT-MAT software package. It is recommended that you keep the manual handy and refer to it when needed. If you are already familiar with ADAPT-FLOOR Pro, you may skip the section on Quick Start, and Modeling and Design Process, since the two programs use essentially the same interface, modeling and design process.

9

Chapter 2

BASIC FEATURES

BASIC FEATURES Chapter 2

11

2 OVERVIEW

This chapter explains the basic features of the program.

2.1 GEOMETRY

A foundation mat or raft as it is also referred to, can be faithfully modeled as it is intended for construction. The following describes the structural components that can be modeled and handled by the program as part of a foundation system;

Slab regions: a foundation mat can consist of one or more slab regions, each with its own shape on plan, and its own thickness. The slab regions can have different elevations, creating steps either at the top or bottom of the foundation system.

FIGURE 2.1-1 VIEW OF A MAT FOUNDATION CONSISTING OF MORE THAN ONE SLAB REGION WITH STEPS BOTH AT TOP AND BOTTOM

Grade beams: Grade beams can be in any number, any dimension and orientation. Grade beams can be standalone or be part of a foundation slab. If they are part of the foundations slab, their structural interaction with the slab in resisting the applied loads is automatically accounted for in the analysis and design steps of the software. Further, the program recognizes the elevation of the grade beams with respect to the foundation slab in both its analysis and design stages.

Chapter 2 BASIC FEATURES

12

FIGURE 2.1-2 VIEW OF A FOUNDAITON SLAB WITH INTEGRATED GRADE BEAMS

FIGURE 2.1-3 PLAN OF A FOUNDAITON SYSTEM WITH ISOLATED FOOTINGS AND GRADE BEAMS


13

FIGURE 2.1-4 VIEW OF A FOUNDAITON SYSTEM WITH ISOLATED FOOTINGS, GRADE BEAMS, AND MATS BELOW WALLS

Pile caps: Pile caps can be modeled either in isolation, or as part of a foundation mat. When integrated with the foundation mat, their interaction with the mat in resisting the applied load will be automatically accounted for by the program.

Thickening below slab: Thickenings below a mat slab to resist punching

shear below columns can be readily modeled with a column-drop/panel tool. The program accounts for the local stiffening of the foundation slab due to added thickness, as well as the resistance it provides for punching shear.

Openings: Openings of regular or irregular geometry can be defined in any

number and at any location. Elevator pits: Significant depressions in foundations slab with perimeter

walls, typical of elevator pits can be modeled in the program and analyzed.


14

(a) Elevator shaft model

(b) Pads below columns

FIGURE 2.1-5 ELEVATOR SHAFTS AND PADS BELOW COLUMNS

AND WALLS, AND ELEVATOR PITS CAN BE MODELED WITH CORRECT GEOMETRY AND ELEVATION

Walls and columns above foundation mats: One story height of walls and columns can be modeled above a foundation system. The program accounts for the stiffness of these structural components when analyzing the foundation. The degree of stiffness of each of these structural components depends on the fixity defined by you at the far end of a wall or a column. The default setting of the program is freedom to displacement and rotation at the far ends of the walls and columns above a foundation. The height of a wall or column above a foundation is taken to be the story height defined by you, but you have the option to modify the height of each wall.

Upturned beams; Beams can be modeled to be entirely above a foundation slab, or partially above and partially below the slab.


15

FIGURE 2.1-6 VIEW OF A FOUNDATION SYSTEM INCLUDIG THE MODELING OF WALLS AND COLUMNS

2.2 SUPPORT CONDITIONS

A foundation system can be supported partially or wholly, on a variety of support conditions as described below:

2.2.1 Soil Support Area

Foundations can be modeled to rest on more than one type of soil. Each soil type will be specified with its own property and the support area it covers. A supporting soil region can be extended beyond the boundary of a mat and below the openings. The program will consider only the resistance of soil that is immediately below the structural members of the foundation. Soil regions modeled extending beyond the boundary of a mat’s structural members and within the openings will not be considered to provide support. Not all the regions of a foundation system need be supported on soil. You may define parts of the foundation to overhang or span unsupported lengths. The soil is represented by Winkler springs, for which you define the associated bulk modulus as part of your input data. The unit for the soil’s bulk modulus is lb/in3. This value typically varies between 100 to 400 pci (between 0.03 to 0.12 N/mm3). In the absence of detailed information 200 psi (0.06 N/mm3) is a reasonable starting point.


16

2.2.2 Compression Only Soil

You have the option to limit the transfer of force between a foundation member and its underlain soil as compression only. This results in separation between the underlain soil and the foundation member, where tension is likely to occur – hence no load transfer. Also, you can specify the soil to resist both tension and compression. The soil region you define provides only up and down support. For a support with capability of resisting forces in the horizontal direction and moments, you will use other options of support, as detailed below.

2.2.3 Soil / Rock Anchors

Soil and Rock anchors are designed to resist tensile forces only. They are used where there is potential of uplift, such as overturning due to high winds, seismic forces, or uplift from raised water table. Under normal conditions, support is provided by soil. But when the load on a foundation results in an uplift, the soil/rock anchors will be mobilized to resist the uplift. The tensile force developed in a soil/rock anchor depends on the user defined stiffness. In principle, soil anchors are “tension only” point supports with specified stiffness values. You will use point springs to model soil anchors.

The default setting of the program is that the soil anchors take only tension in the vertical direction. You define their property in terms of (pounds per inch of extension, kN/mm extension, or tons/cm of extension). The program provides you the option to specify stiffness for displacements other than vertical direction.

2.2.4 Grade Beam Support

Grade beams that are integrated with a mat slab do not need additional support definition. The soil region that supports the mat will also support the grade beam. But for grade beams that are isolated (Fig. 2.2-2) you need to specify a line support along the beams. The stiffness of the support is defined in terms of displacement of the soil support per unit force placed on unit length of the grade beam [lb/in2; kN/mm2; t/m2). Obviously, the wider the grade beam, the stronger will be the resistance of the supporting soil, since the larger contact area mobilizes a larger volume of soil beneath the beam.


17

FIGURE 2.2-2 STAND ALONE AND INTEGRATED GRADE BEAMS

For example if the bulk modulus of the soil is 200 lb/in3, (0.06 N/mm3

units) and the width of the grade beam is 24 inch (600 mm), the resistance of the soil per unit length of the beam to be specified is : 200x24 = 4,800 lb/in2 length of grade beam (0.06x600 = 36 N/mm2 length). In the general case, you will use line spring tool with compression stiffness in the vertical direction to model grade beam supports.

2.2.5 Line Springs

Line springs provide you with a more general support condition than the simple support of a member on soil. The support provided by a line spring can be resistance along one or more of the three principal directions, with or without associated rotational stiffness. The stiffness provided along the length of a line spring is constant. Changes of stiffness along a line are defined by several lines springs, each with its own stiffness.

2.2.6 Point Springs

These can provide both translational or rotational restraints at one or more directions, at one or more locations of your choice on the foundation system. You identify the location of a point spring and specify its stiffness along and about the three principal directions as part of your input data.

2.2.7 Point Supports

You can define a point support anywhere at a foundation system and specify the type of fixity the selected location provides at the selected location. The fixity can be translation along one or more of the principal axes, and/or rotation about each. In addition to location on plan, you define the location of the point support in the vertical direction.

2.2.8 Line Supports

A line support is a more general form of a support condition soil can generally provide for a grade beam. You start by defining the location and length of a line support. Then you specify the type of support that you want the line to provide. You do so by assigning restraints to the line support you have defined. The restraints can translation along one or more principal axis (es), and/or rotation about one or more of the principal


18

direction(s). The vertical location of the line support can be below, above or any other height with respect of the mat foundation.

2.2.9 Piles

Piles are used, where the soil is considered not adequate in providing the support needed for the superstructure. A pile supported mat behaves essentially the same as a column supported slab, since the mat and its load are supported at discrete pile locations similar to a suspended slab supported on columns. There is no design contribution of the soil below the mat in providing resistance is disregarded. The pile supported mats can be best modeled and designed using ADAPT-Floor Pro. When using ADAPT-MAT each pile has to be modeled as a point spring having the same stiffness properties as the pile it represents.

2.2.10 Voids in Soil

Where there is no soil support below parts of a foundation, such as overhang of the foundation of a light building along its perimeter due to loss of moisture in soil, you do not define a soil support. Transfer of force between a foundation and soil can take place only at the locations where you define soil.

2.3 MATERIAL PROPERTIES

Each of the structural components specified, such as slab regions, grade beams, and reinforcement have can be specified with its own material property. Structural components of the same type, such as two columns can each have their own different material properties. You define the properties of the materials to be used in your model in the “Materials” pull-down menu and assign them to the structural components you create.

2.4 LOADS

The complete library and options for definition of loads of ADAPT-Modeler is available for ADAPT-Mat. Among many options, you can define a point load, line loads, and patch loads (distributed load over a defined area) anywhere on the foundation slab. The loads you define can consist of concentrated forces along each of the principal directions and moments applied about each of the principal directions.


19

2.4.1 Load Cases

Each load you define is assigned to a “load case.” This will enables you to group the loads that are associated with a common source. There is essentially no limitation on the number of loads that you may define, nor is there a limitation on the number of load cases. The program comes with default load cases of DEAD, LIVE, and PRESTRESSING along with several other pre-defined cases. Selfweight of the mat is automatically calculated, and at your choice it can be included in your analysis.

2.4.2 Load Combinations

Depending on the building code you select, the program automatically generates the primary load combinations of the code. But, you may edit the program’s defaults, or define additional load combinations. There is practically no limit on the number of load combinations you can define. In addition to reporting the outcome of each load combination, the program has the ability to determine and report the envelope of the analysis results of the load combinations you define.

2.5 BASE REINFORCEMENT

As “Base Reinforcement” ADAPT-Mat allows you to predefine layers of reinforcement either at the top, at the bottom, or both at the top and bottom of the mat slab. The reinforcement can be in one or two orthogonal directions that you define. You also specify the location of each layer within the depth of the mat. The program considers your base reinforcement in its design and reports the necessary reinforcement in addition to your pre-defined base reinforcement.

The base reinforcement you define, can be expressed in terms of (i) bars at given spacing (regular mesh), or (ii) reinforcement areas per unit width of the slab, (iii) or isolated single or spaced bars with given length, size and location, (iv) or a combination of one or more of the above types. Different regions of the mat can be assigned different reinforcement. In other words, you can define different mesh reinforcement specifications for different regions in the mat.

2.6 POST-TENSIONING

ADAPT-Mat features the entire capability of prestressing options that is available in Floor –Pro. This includes full freedom to define tendon layout, post-tensioning system, and stressing operations.


20

2.7 ANALYSIS

Unlike the standard conditions of suspended slabs, the analysis of a mat foundation can be an iterative process. Where there is likelihood of separation of soil from the foundation mat, an iterative solution is required, in order to determine the location and extent of soil/foundation separation.

The analysis process is initiated by assuming full contact of a mat with underlain soil. At each iteration, the program eliminates the regions of the soil/mat contact where uplift occurs, until full equilibrium of the entire structural system through transfer of compressive force between the mat and its underlain soil is achieved. In each iteration, the program re-generates the entire stiffness matrix of the structure, and obtains a solution. For this reason, and the fact that in such conditions superposition of load cases does not apply, the analysis of mat foundations with potential of uplift takes longer to achieve.

It is reiterated that a difference between the analysis of a mat foundation and an elevated slab is that, where uplift occurs, the principle of superposition of solutions does not apply, since each solution with uplift relates to a different structural boundary condition of the structure.

Like ADAPT-Floor Pro, the outcome of the analysis is form of displacements, forces, moments. Stresses in the mat proper are reported, where post-tensioning is defined. However, ADAPT mat generates and reports the distribution of soil pressure below the mats and grade beams.


21

FIGURE 2.7-1 AN EXAMPLE OF DISTRIBUTION OF SOIL PRESSURE

BELOW A MAT WITH FULL SOIL/MAT INTERFACE CONTACT

(a) deflected shape (b) soil pressure

The above demonstration example shows the displacement of a foundation mat under a central concentrated load and overturning moments on the walls (a). The uplift (soil/foundation separation) at the tip of the walls is reflected in the distribution of soil pressure (b).

FIGURE 2.7-2 DISTRIBUTION OF SOIL PRESSURE BELOW A MAT

2.8 DESIGN


22

The design information concludes with a complete code check, using the building code you specify. Where needed, the program determines and reports reinforcement from the library of bars defined by you, or bar sizes of your choice. The program checks both the service (SLS) and strength (ULS) requirements of your selected building code. The reinforcement report of the program includes the number, position and length of each bar on plan of the mat, ready to be used in your structural drawing. If prestressed, the program also gives you a detailed report of stress check, as required by building codes.

2.9 GENERATION OF DRAWINGS

The reinforcement plan generated automatically by the program can be readily exported to either a DXF or DWG file format that you can use to combine with the remainder of your work in a construction drawing.

2.10 LINK WITH OTHER PROGRAMS AND BUILDER DATA EXCHANGE CAPABILITY

If the foundation slab you design forms part of a multi-story building for which you have developed an independent model in a commercially available program, and you have the results of the loads from the superstructure, there are several ways to facilitate the transfer of this information to ADAPT -Mat as applied load.

The common method is to simply enter the load in the program using the loading toolbar

Loads from other software can be formatted into the mat’s data exchange file and be imported to ADAPT -Mat. The program can read and import loads, if the information is formatted according to ADAPT’s Data Exchange File. Details of this file are given in one of the manual appendices.

ADAPT-Mat has the capability of importing solutions directly from several commercially available programs. With time, more programs will be added to the list of software that can directly export their solution to ADAPT-Mat. The programs with direct link with ADAPT are listed in a pull-down menu (File/Import) of your ADAPT-Mat. A direct importation of loads eliminates potential errors in data generation, in addition in a significant saving in time.

23

Chapter 3

QUICK START

QUICK START Chapter 3

25

3 OVERVIEW

This Chapter covers two simple examples giving you a quick introduction to the program. Once you are done with the examples of this chapter, it is recommended to review the Chapter on Tutorial for a step-by-step description of data generation and design.

3.1 OPENING THE PROGRAM

Open the program to display the splash window shown below. Select “Mat/raft foundations/grade beams” option, if not already selected. Click OK to open the main program interface.

Details of the interface and its tools are given elsewhere. You may refer to them, if needed. But, for the current task we limit ourselves to the features that cover our immediate objective.

Capter 3 QUICK START

26

For getting started, we will use the tools that enable us to do the following

o Create a grid to give us a sense of dimension and guide us to create the structure

o Tools to build the mat, such as its geometry and other features o Tool to view the geometry in three dimensions, in order to verify

its accuracy o Tools to define the soil below the mat o Tools to apply load on the mat o Mesh and analyze the mat o View the analysis results

We will introduce and invoke each of the tools listed above one after the other

3.2 EXAMPLE 1

Find the deflection of the foundation mat shown in Fig. 3.2-1 and the distribution of soil pressure below it.

FIGURE 3.2-1 GEOMETRY AND LOADING OF MAT FOUNDAITON

Create a Grid

We will use the tool marked 8 in the toolbar shown below to create a grid of 5 ft spacing as illustrated in the second figure below:

1 2 3 4 5 6 7 8 9 10 11


27

FIGURE ???


28

started on the gives you a list of the steps to follow in order to complete the analysis and design of your mat foundation. The items listed here are discussed in greater detail in the Modeler Manual and in Chapter 5 of this manual.

The suggested steps for the design of a mat foundation are:

o Create the structural model

o Define soil support conditions

o Validate the structural model

o Complete and finalize input data

o Perform analysis

o Prepare to design

o Design

o Generate structural drawings

o Generate structural calculation reports

3.2.1 Create the Structural Model

Use one of the following options to create your structural model

Import an AutoCad file of it (DXF or DWG) and convert it to structural model.

Draw the foundation slab, using the drafting capability of the program.

Import the geometry and load on the model from a multi-story analysis program, such ETABS, or other programs supported by ADAPT-Builder platform.

Use the generic data exchange file format of the program to create and import the geometry of the foundation mat.


29

The common and at the same time more accurate method for the generation of geometry of your structural model is the option 1 – importing an AutoCad file, since most of the commercially available multi-story software does not model the complex foundation geometry with adequate degree of accuracy.

3.2.2 Define Soil Support Conditions

Define the location and properties of the soil support, piles and rock anchors, if any.

3.2.3 Validate the Structural Model

In this step you determine whether the structural model of the foundation slab you have generated and its support conditions are indeed a faithful representation of your requirements, before proceeding with detailed analysis and design. The steps are:

Mesh the structure

Analyze the structure for an arbitrary concentrated load in the central region of the mat

Analyze the structure

View the deflected shape of the structure under selfweight and satisfy yourself that the results look reasonable in shape and magnitude.

3.2.4 Complete and Finalize Input Data

Add post-tensioning tendons, if the structure is post-tensioned

Review and finalize the design criteria among other items, this includes the design code.

Specify reinforcement mesh to be included in your design, if any

Define additional load cases; add loads if necessary

View the program-generated load combinations; edit if necessary

3.2.5 Perform Analysis

Analyze the structure


30

3.2.6 Prepare to Design

Create support lines

Create design sections automatically

View and design strips created. If necessary, modify the support lines and use splitters to refine the design strips created. Conclude your modifications with a re-creation of automatically generated design sections.

3.2.7 Validate the Code Compliance of the Design

If the foundation system is not prestressed, the program automatically provides the adequate amount of the reinforcement, where necessary to meet the requirements of the design code you have selected.

For prestressed foundations, in addition to the reinforcement requirements, the computed stresses must not exceed the code specified threshold. If this condition is not satisfied, the program shows the location with broken lines in violet color. At this stage, you either modify the post-tensioning you have specified, or change other parameters of the foundation, such as thickness and re-try the analysis and design. The re-trial continues, until you accept the solution. In summary:

View the outcome of code check for design sections in X-direction, followed by an examination of the same for design sections in Y-direction.

If there are no purple lines (broken lines) the requirements of the building code you selected is satisfied

If there are purple (broken) lines, the code requirements have not been met ; investigate and fix the problem as described in this manual

Execute the punching shear option – if applicable

View the punching shear stress check on the screen, to ascertain that the calculated stresses do not exceed the maximum allowed by code. The program automatically reports these locations to you on the screen with red color and a note.


31

3.2.8 Generate Structural Drawings

The program provides you with the option to generate structural drawings with detailed information for construction, as described elsewhere in ADAPT-Builder documents1

For an expeditious outcome of your design, use the “rebar generation” tool of the program to generate rebar.

Review the rebar generated and edit the size, orientation, number and length of the bars, if needed.

Add any reinforcement that you consider necessary to complete the detailing of the structure

View/modify the font size and line properties of the drawing suitable for the size of DWG drawing you plan go generate.

Export the drawing to AutoCad for production.

3.2.9 Generate Structural Calculation Reports

Refer to sample report of a mat foundation included in this manual. Using the sample report and the report capability of the program, prepare a similar report for your project.

1 Workshop package of builder

33

Chapter 4

USER INTERFACE

USER INTERFACE Chapter 4

35

4 OVERVIEW

The features of the user interface of the program, description of details of each of the toolbars, and the modeling techniques are detailed in Chapter 3 of the Modeler User Manual. The following describes the tools that are specific to the mat foundation

Describe some from the modeler manual and the remainder here.

4.1 ??

1 2 3 4 5 6 7 8

1 – unchanged 1.1 – between tool 1 and tool 2 add the “Soil Support” tool and its tool tip. 2 – graphics unchanged – limit to creation of column above 3 – graphics unchanged – limit to creation of wall above 4 – unchanged 5 – unchanged

6 – change the bitmap to show the column above (ask Bijan for details).

Slab thickening/Pile Cap

6,1 create a tool graphics as given by Bijan, for a pile foundation. Use the following tool tip:

End-bearing pile

6.2 create a tool graphics as given by Bijan for soil/rock anchor and use the following tool tip.

Soil/rock anchor

7 - rebar

8 – wall and columns above (height)

4.2 SOIL PRESSURE

Chapter 4 USER INTERFACE

36

37

Chapter 5

MODELING AND DESIGN PROCESS

MODELING AND DESIGN PROCESS Chapter 5

39

5. OVERVIEW

This section outlines the steps that you have to follow in designing a conventionally reinforced or post-tensioned mat foundation, using the ADAPT- Mat. You will skip the sections that relate to post-tensioning, if the mat you design is conventionally reinforced. Depending on whether you already have an electronic file of the mat geometry or not, and whether you are familiar with AutoCAD or not there are different options available to you. Refer to the flow chart and the text that follows for the details.

5.1 DESIGN PROCEDURE ??

Chapter 5 MODELING AND DESIGN PROCESS

40

FLOW CHART FOR DESIGN OF MAT (RAFT) FOUNDATION

Design_procedure_builder_10

100306

If you do not have a dwg/dxf of the floor

If you have a dwg/dxf of the floor

}Yes No

Prepare proper layers in AutoCAD

Import dwg/dxf to Builder

Validate the model under single concentrated

load

Enter/edit material properties

Enter/edit design criteria

Enter loads and load combinations

Analyze structure } Enter base reinforcement Validate the solution

Create design strips Create design sections

Design/code check the structure

Examine the design

Is the design acceptable?

Modify structure or other parameters. Try

again

No Yes Exit to generate structural

documents

Rebar drawing PT drawing Calculation Report

Fabrication drawing (shop/installation drawing)


41

If you have an electronic file of the floor slab, and also have some knowledge of AutoCAD.

o Create layers that you will be using to convert the drawing into

structural model for analysis and design. For example, create a layer for columns and copy or move the columns on the CAD drawing to that layer. And, create a layer for walls, for openings, for beams, and for distinct slab regions. This will enable you to convert the CAD entities directly to the associated structural components, once you import your drawing to ADAPT Floor Pro. Remember when you import walls and columns from the CAD drawing, you need to move them above the mat.

Open ADAPT-Mat

Import and Calibrate the floor plan

Create and Validate the Structural Model

o If the dwg was preprocessed into proper layers either by you or a drafting technician in your office, open the layers of each of the structural components one after the other and transform them to structural components.

o If the dwg was not pre-processed, simplify the cad file by deleting the information that is not necessary to the generation of the structural model and its analysis, such as entities like furniture if they exist in the cad file.

o Mesh the structural model o To validate the structural model, apply an arbitrary single concentrated

load over the mat for the purpose of obtaining a solution that includes displacements and changes in soil pressure. It is essential to apply a load, since if the mat is of uniform thickness and is not loaded, its deformation will simply be a uniform displacement downwards and will not generate adequate information to afford visual validation of its structural modeling.

o Obtain a solution under a single concentrated load, in order to check the model. Place the load somewhere near the center of the mat and give it an arbitrary value. When you attempt to obtain a solution the program is likely to prompt you that you have not defined the loads it expected, press “continue” to bypass the prompt. You will define the design loads later.

o Using engineering judgment, validate the solution obtained by examining the deflected shape of the structure in 3D viewer and making sure that the deflection shape reported for the mat is reasonable for the load applied.

o Make corrections to the model, until satisfied o Save data


42

View/Edit Design Criteria

o Select/verify the building code to be used o View/edit the items listed under “analysis and design options” o Select the type of reinforcement you prefer for punching shear design,

stirrups or shear studs o Select the size of reinforcement bars to be used by the program for

bending and one-way shear o View each of the other tabs of the design criteria and edit the default

values if necessary o Save data

View/Edit Material Properties

o View/edit concrete material properties. Note the concrete weight specified for use in selfweight calculation

o View/edit steel material properties o View/edit prestressing material properties, if the mat is prestressed o Save data

Apply Loads

o If the load cases you plan to use are more than “dead”, “live”, “selfweight” and “prestressing” do the following2: Go to “Load Case Library” and enter the label of the other

load cases that you plan to use. Once the label is listed in the library, enables you to enter the associated loads.

o Enter the loads of each load case. Make sure that each load you enter is assigned to the correct load case listed in the load case library.

Review/Edit Load Combinations

o Go to load combination dialog window. Depending on the building

code you have selected, the program will display a number of load combinations. Review/edit the load combinations displayed in the load

combination dialog window for relevance and accuracy. For each of the default load combinations and the ones you

2 Note that a “load case” is different from “load combination.” Using basic load cases, you can combine them in many different ways. The load cases are the basic constituents of the load combinations. The prestressing load case includes both “prestressing” and “hyperstatic” cases.


43

are going to add, make sure that the correct “Analysis/Design Option” is selected. In most cases you would select “No Code Check.” If not clear, click the “Help” button on the same dialog window to be guided in your selection.

It is not necessary, but is advisable for post-tensioned mats to create a load case for prestressing only “PT” with no code check. This will enable you to view the effectiveness of the post-tensioning you have defined in distributing the applied load over the mat.

Likewise, if you have unusual load cases, make sure that for each of the load cases you define a load combination. The objective is to be able to view the results of the unusual load case on its own, in order to evaluate its validity. If there is likelihood of uplift of the mat (separation of parts of the mat from underlain soil), you should only have one load combination. The reason is explained in the background of the program.

Before closing the load combination by pressing “OK,” make sure that you have at least one instance each of the following required code checks: “Serviceability,” “Strength.” If there is post-tensioning, you may want toad a load combination for the “Initial Condition,” at transfer of prestressing to the slab.

Enter/Edit Base Reinforcement

Base reinforcement is the reinforcement you like to place in the mat slab, regardless of the outcome of the calculations. But, at the same time, you want presence of the reinforcement you have specified as base reinforcement to be fully accounted for in design. In other words, you want the program to report only the reinforcement needed in excess of what you have specified. The base reinforcement generally consists of a bottom and or top mesh, added pre-defined bars below the columns (number, size and length)3, and pre-defined longitudinal bars at the corners of beam cages.

o Enter mesh reinforcement, if any o Enter beam reinforcement (corner bars), if you require specific

number and size o Enter single bars in size, length and number at locations of your

choice. o Verify each of the reinforcement types on the computer screen o Save

Enter Post-Tensioning Tendons

3 In many instances, you may wish to place a given number of bars of pre-defined size and length below the support in a given direction. The program allows you to define these and will report whatever is needed in addition to your pre-defined bar layout.


44

o Enter the post-tensioning tendons for the entire structure. o View the tendons in 3D viewer with a magnification factor of 6 or

more for the Z-direction. Hide the walls and columns to obtain a good view of the slab and its interior. Make sure that the tendon profiles are acceptable.

o Save

Analyze Structure

o Simply click on “Analyze the Structure” to obtain a solution. o Save

View/Validate Analysis Results

o Go to 3D viewer and view the deflected shape of the structure for the

principal load cases. These are “service”, “post-tensioning” and other load cases that you have defined. If the deflected shapes and their magnitudes appear acceptable, you may proceed to the design stage. Otherwise, adjust or correct the suspect data or parameters.

Create Design Strips in X-direction

o Use the support line wizard to create support lines along one of the

principal axes of the structure. If the columns/walls do not line up, the support line will not be straight. This should not be a concern, since the program can automatically adjust the direction of the calculated reinforcement to that of your choice independent from the orientation of associated support lines. Alternatively, you can draw support lines along the directions where you are likely to place added reinforcement, where needed.

o Create “Design Strips” automatically for the support lines created above. Use the FEM option for design strip creation.

o Use the color rendering of the design strips to make sure that the strips created cover the entire floor area. Each part of the floor area must have been assigned to a design strip.

o Correct the errors if any. o If based on your judgment, the geometry of the strips created by the

program is not a good arrangement, use splitters to modify the program’s choice.

o Re-create the design strips, until the selection is acceptable to you. o Save

Create Design Strips in Y-direction

o Follow the above procedure to create design strips orthogonal to the


45

first direction. Select the X and Y strips to be as close to orthogonal condition as practical.

o Save

Create Design Sections

o Click on the “Create Design Sections Automatically” to generate design sections for each of the design strips.

o Activate the “Display Design Sections” tool from the “Support Line Results/Scale Toolbar” to view the design sections generated for each of the two orthogonal directions. Verify the following:

If the number of sections for any given span is not adequate,

select the associated support line and increase the number of design sections.

There should be a design section at each face of a wall, column, or end of a grade beam.

There should be a design section at the face of each thickening below a column (shear drop).

Make sure that for each direction the design sections adequately cover the entire surface of the floor.

o Save

Design the Design Sections

o Activate the code check of the structure and the calculation of the necessary reinforcement by selecting “Design the Design Sections.”

o If the mat is post-tensioned, the program reports the design sections that do not meet the minimum requirements of the code in broken magenta lines. Otherwise, the design sections will be shown in green. Green display of a design section means that the code requirements for that section are met. If the mat is not prestressed, the program provides added reinforcement, where needed to comply with the design code you have selected.

View Details of the Design Outcome and Make Adjustments if Necessary

o To accept the design, select several of the critical design strips one

after the other, and view the outcome of the design by displaying the following:

Reinforcement reported for each code check and the

envelope of reinforcement The layout of reinforcement (selection of bar size, and

length) Computed stresses and their comparison with the allowable


46

values, if the mat is post-tensioned. Otherwise, there will be no stress check and stress reports.

o If post-tensioned, view the stress details of each of the design strips

that have failed the code check. Based on the location of the design section, use your judgment to determine which of the entry values have to be adjusted. In most cases, the amount and profile of post-tensioning are the choice. Make the necessary modification and repeat the analysis/design.

Perform Punching Shear Check4

o Select the “Punching Shear Check” tool to perform code check for punching shear.

o View the values of the punching shear reported by the program on the screen. If necessary and permissible, the program reports the necessary reinforcement. The program also reports, if a section does not pass Code.

o Save data

5.2 CONCLUSION OF DESIGN

Once you reach this stage, your design is completed. The steps to follow are to prepare the structural documents. These are:

o View and adjustment of rebar in orientation and position, if necessary.

Refer to Appendix B to learn how to adjust the reinforcement. o Generation of rebar drawings o Generation of post-tensioning drawings, if applicable o Generation of shop drawings, if the mat is post-tensioned o Generation of the package of structural calculations

4 Punching shear check can also be performed after the completion of the “analysis” and prior to the “design.”

47

Chapter 6

TUTORIAL

TUTORIAL Chapter 6

49

6.1 GENERATE STRUCTURAL MODEL

Generate a structural model, either by importing a DWG file and converting it to structural components, or creating your own structural model using the tools of ADAPT-Modeler.

6.2 ANALYSIS

First run for model validation:

o Go to the FEM pull-down menu and select Automatic Mesh Generation. Accept defaults of the program

o Once meshing is complete, click on Analyze Structure in the FEM pull- down menu. Since you have not defined all the default loads of the program, such as “dead, and live,” the program will solve only for the concentrated load defined earlier. Ignore the warnings regarding other loads not having been defined.

o Once analysis is complete, select View Analysis Results from the FEM pull-down menu. This opens the 3D viewer of the program to display the solution

o Once in 3D viewer, select service load combination and Z-Translation. This is vertical displacement of the structure. Then, click on the tool with two light-bulb graphics. This will display the deflected shape under selfweight only.

o Zoom, rotate and view the results thoroughly to ensure that the deflected shape under selfweight looks reasonable. In particular, make sure there is no deflection where the structure was intended to have been supported. Correct the structural model if the deflected shape and values under selfweight do not appear reasonable.

Add loads:

o Go to the Loading/Load Case Library pull-down menu and add load cases, such as dead load, live load, prestressing and other load cases that you want to include in your design.

o Display the Loading tool bar and enter loads.

o Add prestressing: If the structure has prestressing, add the prestressing tendons. Refer to the Modeler User manual for details

Chapter 6 TUTORIAL

50

on how to enter prestressing tendons and edit their properties (is this where the information resides???}

Review/edit design criteria:

Go to the Criteria pull-down menu, select General and review the default values of each of the tabs. Modify if necessary. In particular, make sure that you select the building code of your choice. Once you select/confirm the building code, the program automatically creates the default load combinations of the building code you selected.

Edit material properties:

Go to the Materials pull-down menu, and enter the material properties for concrete, nonprestressed steel and prestressed steel, if applicable. If there is more than one concrete material, steel or prestressing in your structure, this is the time to give a label to each of the new materials used and define their properties. In your modeling, the program has assumed that all the components of the structure you created have the material names entered on the first line of each of the lists. If you added any new material to the list of existing materials, open the property box of the structural components that must have the new material and change their material name to the one you created.

Add extra load combinations for validation:

o Go to the Loading pull-down menu. Select Load Combinations/FEM Side menu.

o Create a load case for selfweight only5, with No Code Check option.

o View and edit the load cases and load combinations. If you have prestressing, create a load case (PT) for prestressing only.

o From the FEM pull-down menu, select Analyze Structure.

o Once the analysis is complete, go to View Results from the FEM pull-down menu. Check the deflection shape of each load case and load combination, to make sure they look reasonable. If deflections do not appear right, go back to the loads, criteria and prestressing layout, if needed, in order to fix the problem.

5 Once you add new loads, the selfweight load case is likely to become part of other load combinations. That is why you need to create a selfweight load combination. Also, if you plan to have skipping of live load, leave this option to the last, after you have made sure that the model you have created works well.

TUTORIAL Chapter 6

51

Design:

o Using the support line wizard from the Model Strips pull down menu, create support lines in two orthogonal directions. Make sure that you assign to the support lines in one direction X-direction, and to its orthogonal direction Y-direction.

o Go to the FEM pull down menu and click on Create Design Sections Automatically. Save data.

o From the FEM pull-down menu click on Design the Design Section(s).

Check punching shear values:

o If you have a column that terminates on the foundation slab, click on Punching Shear Check.

o Display the Support Line Results Scale toolbar from the User Interface pull-down menu.

o Click on the tool Display Punching Shear Design Outcome. This is the last tool on the right side of the toolbar. This tool will turn any locations that fail the punching shear requirements purple.

o To view the stress ratios, click on the Numerical Display Tool on the same toolbar.

Generate/view reinforcement:

o From the FEM pull-down menu, click on Generate Rebar Drawing to compile a rebar drawing.

o From the User Interface pull-down menu, display the Reinforcement Toolbar. Click on the tool Display/Hide Rebar to make the reinforcement visible. This is the tool with yellow circle.

o Use the capabilities of the other tools on this toolbar to view and edit the display.

Generate rebar drawings:

o Using the tools of the Reinforcement Toolbar, select the reinforcement that you want to be shown on the structural drawing.

o Edit/move the reinforcement annotation to make it arrive at a clear presentation. The extensive editing options for the reinforcement

Chapter 6 TUTORIAL

52

will be available to you, if your computer is loaded with the DRD (Dynamic Rebar Drafting) module. Otherwise, the extent of editing the rebar shown on the drawing will be limited. In this case, you will do the editing in the AutoCad environment, once you export the rebar drawing to AutoCad.

o Change the font size to values suitable for printing on the paper size you are going to select. Or, if you plan to export the work to AutoCad and complete the drawing in AutoCad environment, select the font size, and line properties that suite your paper size.

o From the File pull-down menu, select print preview to examine the features of the drawing you are going to print.

o Print the drawing or export it to AutoCad, using the Export DXF/DWG tool of the program that is accessible from the File pull-down menu.

o In the same way, generate other rebar drawings such as top bars on one drawing and bottom bars on another.

Generate tendon layout drawings:

On engineering drawings, most engineers group tendons into tendons in one-direction (such as banded tendons) and tendons in other direction (distributed tendons).6 If you plan to show the tendons in two drawings, you must first group them, following the instructions below. If this is not the case, go to the next step.

Group tendons:

o From the Settings pull-down menu, select Grouping. This opens the group library. Add two group names, such as “banded tendons,” and “distributed tendons.”

o Using Select/Set View Items, turn off everything except tendons and the other basic information you need to identify the tendons. In most cases, it is adequate to retain the tendons, slab outline and column supports.

o Select as many tendons of one group as practical.

o From the Modify pull-down menu, select Modify Item Properties.

o Once the Modify Item Properties dialog windows open, select the Tendon tab.

6 For generating fabrication drawings, tendons are grouped more extensively, assigning unique group identification to tendons of same length and profile.

TUTORIAL Chapter 6

53

o In the Tendon tab, select the group to add the selected tendons. Press OK to close the Modify Properties dialog window.

o Repeat the above steps, until all tendons are assigned to their respective groups.

o Go to the Grouping Dialog Window and make only one group of tendons visible, such as distributed tendons. Once you have printed the drawing for this group, hide this group and make the next group visible.

Generate single report:

o From the Reports pull-down menu, select Single Default Reports/Graphical/Tendon Plan.

o In the dialog window that opens, select the following, then click OK.

Tendon ID

Control point heights

Number of strands

Elongation (if you selected the option in data generation)

Stressing/dead end (if you selected the option in data generation)

Generate compiled report:

From the Reports pull-down menu, click on Compiled Reports. Select the items of your choice and send to printer.

6.3 EXAMPLE??

6.3.1 Model the Geometry and Boundary Conditions

You can generate a structural model in several ways. (i)If you have dwg/dxf of the floor, you can import a DWG file and convert it to a structural model (1B-3B), or (ii) if you do not have dwg/dxf of the floor, you can simply draw the structure (1A-3A) as we will do in this tutorial. The last option is the quickest way to become familiar with the environment and principal features of the program.

Chapter 6 TUTORIAL

54

Generate Structural Model [3]

Open the program in either “American” or “SI” units. In this

tutorial we will cover both systems of units.

In order to create a somewhat realistic structure, we will start with a grid to give us a sense of dimension.

From the main toolbar click on the Grid Settings tool ( ). The following dialog window opens (Fig.1-1). Select 5 ft spacing and click OK.

FIGURE 1-1 GRID SETTING DIALOG WINDOW (American units)

From the User Interface pull-down menu, select the Build Toolbar.

The following (Fig. 1-2) tool bar will display. We will use this toolbar to create the geometry of our floor slab.

FIGURE 1-2 BUILD TOOLBAR

This toolbar enables us to create the geometry of a structural model7, including specification of any reinforcement (base reinforcement, such as a mesh) that we want the program to account for when it calculates its

7 The plus sign “+” on the graphics of each tool means that the tool is for “generation” of what its graphics implies.

TUTORIAL Chapter 6

55

reinforcement. However, for this tutorial, we will limit ourselves to the first three tools, that is to say “slab” “column” and “wall”.

Click on the Create Slab Region tool ( ). The mouse cursor changes shape to a simple cross line. With the help of the mouse, click at four corners of the slab. Use the grid to create a slab that is approximately 60x60ft (18mx18m). If the grid shown is too large or

too small to work with, use the dynamic zoom ( ) tool to adjust the size.

o After you click on the fourth vertex of the slab, press “C” to

close the slab boundary. Your slab should look similar to Fig. 1-3.

o Next click on “Esc” or right-click the mouse to exit the mode of creating slab region.

o To enter the slab thickness, place the mouse on the slab boundary and double click on it. The property box of the slab (Fig. 1-4) will open. In the “Thickness” data field, enter 16 in (400mm).

o Click on the check mark at the top left of the dialog box. The changes you make in the dialog box will be applied only if you click on the check mark after you make a change. Then click on the top right “x” to close the dialog box.

FIGURE 1-3 PLAN VIEW OF SLAB

Chapter 6 TUTORIAL

56

FIGURE 1-4 SLAB REGION PROPERTY WINDOW

Click on the Create Column tool ( ) to generate columns.

o Position the mouse at the intended location of each column, and left-click the mouse to insert a column. Each time you left-click the mouse, the program inserts one column.

o Once all the columns are in place, either press “C “or right click and select “Exit” the column insertion mode.

o Target to place the columns at about 30 ft (9m) from left and right side and 15ft (4.5m) from top and bottom. If a column is not at the location of your choice, simply click on it. Pick its center with the mouse and drag it to the location of your choice.

o If you have created too many columns, click on the extra columns and use the “delete” button on the keyboard to erase them.

o If you have too few columns, repeat the entire procedure by clicking on the Create Column tool.

o You can view the column properties created by the program by double clicking on a column to open its property box (Fig. 1-5).

o Change the cross-sectional dimensions of the Column to a reasonable value. In the figure shown, the Column is assumed to be circular with of 24inch (610mm) diameter.

TUTORIAL Chapter 6

57

FIGURE 1-5 COLUMN PROPERTY DIALOG BOX

Click on the Create Wall tool ( ) to generate walls.

o The procedure to create a wall is the same as columns. o Position the mouse at one end of the wall and left-click the mouse.

Next left click at the other end of the wall to insert a wall. Each time you left-click the mouse at both ends of the wall, the program inserts one wall.

o Once all the walls are in place, press Esc to exit the wall insertion mode.

o Target to place the walls at about 10 ft (3m) from left side and 15ft (4.5m) from top and bottom. If a wall is not at the location of your choice, either change the location using property box or drag the two ends of the wall with your mouse to the location of your choice.

o If you have created too many walls, click on the extra walls and use the “delete” button on the keyboard.

o If you have too few walls, repeat the entire procedure by clicking on the Create Wall tool.

o You can view the wall properties created by the program by double clicking on each wall to open its property box (Fig. 1-6).

o Change the thickness of each wall to a reasonable value. In the figure shown, the wall is assumed to be 12in (300mm) thick.

Chapter 6 TUTORIAL

58

FIGURE 1-6 WALL PROPERTY DIALOG BOX

Next step is to create the soil support. From the User Interface pull-down menu, select the FEM Supports and Spring Creation Toolbar. The following (Fig. 1-7) tool bar will display. We will use this toolbar to create the soil support for our floor slab.

FIGURE 1-7 FEM SUPPORTS AND SPRING CREATION TOOLBAR

o Click on the Create area Springs/Soil Supports tool ( ). The mouse cursor changes shape to a simple cross line. With the help of the mouse, click at the four corners of the slab. You can also click at points outside of the slab too. The program disregards the soil support not below slabs or grade beams.

o After you click on the fourth vertex of the slab, press “C” to close the soil support/area spring.

o Next click on “C” or right-click the mouse to exit the mode of creating the soil support/area spring.

o To enter the soil properties, place the mouse on the soil support/area spring and double click on it. The property box of the support (Fig. 1-8) will open. In the “kza” data field, enter 100 pci(0.027 N/mm3) and select “compression only” from drop down list for “Spring/Soil type”.


TUTORIAL Chapter 6

59

FIGURE 1-8 SOIL/AREA SPRING PROPERTY DIALOG BOX

The plan view of the structural model with all the components entered is shown in Fig.1-9.

FIGURE 1-9 PLAN VIEW OF THE STRUCTURAL MODEL

Click on the “View Model”( ) tool to open the 3D viewer of the model.

Chapter 6 TUTORIAL

60

Use the different modes of display ( ) to see the model in line drawing or see-through graphics (Fig.1-10).

Rotate ( ) and zoom the model to examine its geometry. Close the 3D viewer. The program brings you back to the main screen

showing the plan of your model.

FIGURE 1-10 THREE-DIMENSIONAL VIEW OF THE STRUCTURAL MODEL

6.3.2. Analyze and View Results

Mesh the Structural Model

From the pull-down menu bar select FEM and click on Automatic Mesh Generation to open the dialog box shown in Fig. 2-5, and accept the default values.

FIGURE 2-5 AUTOMATIC MESH GENERATION

TUTORIAL Chapter 6

61

After the completion of meshing, the program will display the meshed slab similar to Fig. 2-6. Depending on the details of your structural model, it is possible that the program will interrupt, display several pink circles on your model and the message box shown in Fig. 2-7. Click on “Continue.”

FIGURE 2-6 PLAN VIEW OF THE SLAB MESHING

FIGURE 2-7 MESSAGE BOX FOR SUGGESTED CELL SIZE

We will now clear the screen from the mesh and continue with the analysis process.

Click on the Select/Set View Items tool ( ). Open the tab Finite Element and de-select the check box “Shell/Cell Element”. Click the OK button to validate your selection. This should clear the display of the mesh from your screen.

Save the data.

Chapter 6 TUTORIAL

62

Analyze the Structure

From the FEM pull-down menu select Analyze Structure ( ) tool. Then you will see the warning as in Fig 2-8. Click “Continue”. This will perform the finite element analysis of the structure and report its completion on the computer screen. Save the data.

FIGURE 2-8 ANALYSIS WARNING WINDOW

View the Analysis Results

From the FEM pull-down menu, click on the View Analysis Results ( ) tool. This will bring up the viewer screen, as shown in Fig. 2-9. Next, we will view the deflection contour of the Slab.

Click on the Load Cases/Combinations tab on the bottom left of the screen.

From the menu that opens, select Service Combination. Click on the Results tab on the top left region of the screen. From the list of results available select Z-Translation. This is

the deflection in the vertical direction. Select Color Contour tool. Click on the Display Results tool. This button turns the

results on and off. Figure 2-9 is the display of the viewer screen showing the contour of the deflected shape of the Slab. To view a 3D-presentation of the structure’s deflected shape as shown in Fig. 2-10, click on the Warp Display tool.

TUTORIAL Chapter 6

63

(a) US units

(b) SI units

FIGURE 2-9 BUILDER VIEWER SCREEN SHOWING THE DEFLECTION CONTOUR

Chapter 6 TUTORIAL

64

Use the Rotate tool to view the deflected shape in three-dimensions (Fig. 2-10).

FIGURE 2-10 THREE-DIMENSIONAL VIEW OF THE DEFLECTED SHAPE

6.3.3 Set Design Criteria [5]

The various options for design, such as building code to be used, preferred reinforcing bar size, cover to reinforcement and more are all grouped under the Criteria pull-down menu. First select the design code; for this tutorial, choose ACI 2008/IBC 2009. For other criteria assume that the default values of the program are acceptable.

6.3.4 Enter/Edit Material Properties [6]

Next step is to enter material such as concrete, steel and prestressing properties. These properties can be entered in the input screens under Material pull down menu. The program will provide the default values associated with the design code selected. For this tutorial, we would assume that the default values of the program are acceptable. Those are given in the Fig 4-1.

TUTORIAL Chapter 6

65

You can enter as many types of materials you want by clicking “Add” button at the left of each material input screen. Select the material type you want and enter the corresponding properties.

(a) CONCRETE

(b) MILD STEEL

Chapter 6 TUTORIAL

66

(c) PRESTRESSING

FIGURE 4-1 MATERIAL PROPERTY DIALOG BOX

6.3.5. Enter Loads and Load Combinations [7]

Next step is to enter the remaining loads and the load combinations.

6.3.5..1. Apply Load

The procedure to apply the load is the same as we described in section 2.1. From the Loading pull-down menu select Display Loading Toolbars. The toolbar shown in Fig.5-1 will be placed on your computer screen

FIGURE 5-1 LOADING TOOLBAR

o Click on the Create Point load/Moment tool ( ). The mouse cursor changes shape to simple cross line with c shape. Position the mouse at the intended location of the load.

o Target to place the load at the center of the each wall. If it is not at the location of your choice, simply click on it. Pick its center with the mouse and drag it to the location of your choice.

o You can view the load properties created by the program by double clicking on the load to open its property box (Fig. 5-2).

o Select the “Load case” as “Live load” from the drop down list and enter “Myy“ as 500 k-ft (678 kN-m) (Fig. 5-3).

TUTORIAL Chapter 6

67

FIGURE 5-2 LOAD PROPERTY DIALOG BOX

FIGURE 5-3 PLAN VIEW SHOWING LOAD

5.2. Enter Load Combination Based on the building code set in the Criteria, the program creates the appropriate load combinations. We will now add to the load combinations of the program a “Selfweight” load case. The objective is to learn how new load combinations can be created, or a pre-defined load combination can be edited.

Chapter 6 TUTORIAL

68

From the Loading pull-down menu select Load Combinations. The dialog window shown in Fig.5-4 opens. It shows the load cases and load combinations of the building code selected. In this case the combinations refer to ACI 2008 and IBC 2009 (displayed below the Combination list data window). Note that if you don’t uncheck the prestressing load case from the load case library that we described earlier, the load combinations will show “Prestressing” and “Hyperstatic.” These are the defaults of the program. Since, in this tutorial we are not using prestressing, the program will automatically delete those from the combination as soon as you enter the analysis stage. Once deleted, they will not appear in the combination. Any loading, or load case for which you wish to have an independent solution to view or report, must appear on the Combination list shown on top of the dialog window. Do the following to add the selfweight load case to the list of combinations.

From the Load cases combo box, click on “Selfweight.” Click on “Add” button to bring it to the Combination Parts window. Using “Delete” button, remove all the other load cases that appear in the

Combination Parts. Assign a name to the load case in the Label data field. Enter “SWGT” as

the name of this load combination. Note that the label of a load combination cannot be the same as that of a load case.

From the Analyze/Design Options combo box, select “No Code Check.” The options of this combo box tell the program what to do with the solution of the load case. As you note, the options are: to perform a “Serviceability, Strength, Initial, Cracked Deflection or No Code Check.” In this case we intend to view and examine the solution.

Click Save under the Combination list window. Press OK and close the window. Save the data.

TUTORIAL Chapter 6

69

FIGURE 5-4 LOAD COMBINATION DIALOG WINDOW

5. Enter Base Reinforcement [8] From the User Interface pull-down menu select Reinforcement Toolbar. The toolbar shown in Fig.6-1 will be placed on your computer screen

FIGURE 6-1 REINFORCEMENT TOOLBAR

o Click on the Create Mesh Reinforcement tool ( ). The mouse cursor changes shape to a simple cross line. With the help of the mouse, click at the locations of your choice; for this tutorial, click at the four corners of the slab. You can also click at points outside of the slab too. The program disregards the reinforcement not below slabs.

o After you click on the fourth vertex of the slab, press “C” to close the mesh reinforcement.

o Next click on “C” or right-click the mouse to exit the mode of creating the mesh reinforcement.

o To enter the reinforcement properties, place the mouse on the mesh reinforcement and double click on it. The property box of the mesh reinforcement (Fig. 6-2) will open. Select the bar location, CGS and bar

Chapter 6 TUTORIAL

70

area/size of your choice. However, for this tutorial, provide as shown in Fig 6.2.


FIGURE 6-2 MESH REINFORCEMENT PROPERTY DIALOG BOX

o Alternatively you can enter the mesh reinforcement using Mesh

Reinforcement Wizard tool ( ). o First select the slab region or regions over which you want to apply mesh and

then click on Mesh Reinforcement Wizard tool ( ). The property box similar to the one in Fig 6-2 will open. Select/Enter the properties and click create at the bottom of the screen. This will create the mesh reinforcement of your selection.

o The plan view of the structural model with base reinforcement is shown in Fig 6-3.

TUTORIAL Chapter 6

71

FIGURE 6-3 PLAN VIEW SHOWING MESH REINFORCEMENT

6. Enter/ Import PT tendons [9]

Since in this tutorial we are not using prestressing, we are going to skip this step. ??

Having defined the geometry, design code, loading, load combinations, mesh reinforcement and accepted the other defaults of the program, such as material properties and other design criteria we are now ready to analyze the structure.

7. Analyze the Structure [10]

From the FEM pull-down menu select Analyze Structure ( ) tool. This will perform the finite element analysis of the structure and report its completion on the computer screen. Save the data.

8. Validate the Solution [11]

You can validate the solution by viewing the analysis results using View Analysis Results ( ) tool in the FEM pull-down menu. From the FEM pull-down menu, click on the View Analysis Results tool and view the deflection as described in section 2.2.3. Make sure that the deflection displayed makes sense to you. Also you can view the soil pressure to see whether that is acceptable to you or not. Figure 9-1 is the display of the viewer screen showing the contour of the deflected shape of the Slab. To view a 3D-presentation of the structure’s deflected shape as shown in Fig. 9-2, click on the Warp Display tool.

Chapter 6 TUTORIAL

72

(a) US Units

(b) SI Units

FIGURE 9-1 BUILDER VIEWER SCREEN SHOWING THE

DEFLECTION CONTOUR

TUTORIAL Chapter 6

73

Use the Rotate tool to view the deflected shape in three-dimensions (Fig. 9-2).

FIGURE 9-2 THREE-DIMENSIONAL VIEW OF THE DEFLECTED SHAPE

Next, we will view the soil pressure contour of the slab.

Click on the Load Cases/Combinations tab on the bottom left of the screen. From the menu that opens, select Service Combination. Click on the Results tab on the top left region of the screen. From the list of results available select Soil Pressure. Select Color Contour tool. Click on the Display Results tool. This button turns the results on and off.

Figure 9-3 is the display of the viewer screen showing the soil pressure contour of the slab.

Chapter 6 TUTORIAL

74

(a) US units

(b) SI units

FIGURE 9-3 BUILDER VIEWER SCREEN SHOWING THE

SOIL PRESSURE CONTOUR

TUTORIAL Chapter 6

75

9. Create Design Strips/Create Design Sections [12]

9.1.Specify Support Lines (Load Path Designation)

The specification of “Support Lines” determines the direction along which we envisage to place the reinforcement. This is typically along the lines of columns/walls (lines of support). In this tutorial we specify the load path along the X-direction of the slab and determine its reinforcement. In an actual design, a similar operation must be carried out along the Y-direction.

Load path consists of selecting support lines, and designation of a tributary to each of the support lines. At completion, each part of the floor must have been assigned to a support line to carry its load. For the two columns and two walls of the structure at hand, two support lines in the X-direction can be identified. We are going to use the Support Line Wizard tool to generate them automatically. Support lines can also be generated manually. Further, a support line generated either automatically, or manually, can be modified by you, if its details are not acceptable to you. In general, however, it is easiest to let the program generate them automatically.

The wizard works by searching for supports, namely columns and walls, along a slab band defined by the user. It connects the supports detected within the band together to form a support line. The direction and width of the slab band, within which supports will automatically be sought and connected, are defined by the user. Here is how it works.

From the Model Strips pull down menu items, click on the Support

Line Wizard ( ) tool. The dialog box shown in Fig. 10-1 opens. In the Support Line dialog box select:

o X-Direction from the combo box. o For the band width to seek supports select 3 ft (1m).

In large floor areas, it may become necessary to define Support Lines that terminate within the interior of a Slab. That is why in the next input cell Length to search for supports we define a maximum length along which we expect the program to seek a support. In this case, we specify a length much longer than the length of the structure (300 ft; 100 m), since the floor slab is simple.

The last data input cell, Angle for Wall modeling considers whether a Wall encountered within the band of support lines should be considered to fall along the support line, or the support line should cross it. If the angle the wall makes with the direction of the band exceeds the value entered in the data cell (30 degrees shown in the

Chapter 6 TUTORIAL

76

figure), the Support Line will cross it. Otherwise, the support line will pass along the wall.

FIGURE 10-1 DIALOG BOX OF SUPPORT LINE WIZARD

After pressing OK, the Support Line Wizard dialog box closes. The

command line (the line at the bottom of your screen) instructs you to select two points, one after the other, to identify the direction of the Support Line. Click at two points, one next to each of the supports. An image similar to Fig. 10-2 appears. Since the scanning area displayed contains the two supports, which we intend to act as supports, click on Yes in the dialog box. The dialog box closes and the screen displays the support line selected for the top two supports as shown in Fig. 10-3. Note that this figure also shows the support lines for the lower two supports, that we are going to create next.

TUTORIAL Chapter 6

77

FIGURE 10-2 PARALLEL LINES SHOWING THE SLAB BAND FOR POTENTIAL SUPPORTS

FIGURE 10-3 SUPPORT LINE ALONG X-DIRECTION

o Repeat the same for the second support line covering the lower two

supports.

This completes the creation of support lines for the X-direction. We will not pursue the creation of support lines in the Y-direction in this tutorial. As an alternative to the automatic generation of support lines, in the following we will create the second support line manually. From the Model Strips pull down menu items, click on the Create Support

Line tool. In creating a support line manually, it is critical that you “snap” the

support at the center of columns and walls you identify as supports. If you do not snap at these supports, the program will disregard them. Also, you must snap at the edges of the floor slab boundary for the program to recognize where the support line starts. There are tools that make this operation simple. We will describe and use these tools next.

Use the Snap to Nearest ( ) tool and click near the edge of the slab. The

support line will pick the Slab edge; or for columns and end of walls, we must use the Snap to Endpoint ( ) tool.

Select the Snap to nearest tool. Click to the left side of the slab edge, where you want the support line to

start. Select Snap to Endpoint ( ) tool and deselect all other snapping tools.

Chapter 6 TUTORIAL

78

Snap to the first endpoint of the first wall from the left. Snap to the second endpoint of the first wall from the left. Snap to the endpoint of the column from the left. Select the Snap to nearest tool and deselect all other snapping tools. Click to the right side of the slab edge. Press the “C” key to close the support line.

The Support Lines generated in the X-direction should resemble those shown in Fig. 10-4.

FIGURE 10-4 SUPPORT LINES ALONG X-DIRECTION

9.2.Generate Design Strips and Design Sections Each Design Strip is broken down into spans and cantilevers, if applicable. Each span and cantilever is designed at several points along its length. At each design point along a support line, a design section is automatically created. A design section is a section (cut) normal to the support line and extends on each side of the support line to the next tributary or slab edge. The number of design sections for each span has a default value between 6 and 12, but can be changed by you. In addition to the specified number of design sections, the program automatically selects a number of design sections at specific locations. These are at each face of column, at the end of each wall, and at midspan. For each span or cantilever, the design sections are equally spaced. Also, to avoid excessive output, the automated generation, checks the spacing between design sections against a default minimum spacing8.

Click on Generate Design Sections Automatically tool from the

FEM pull down menu shown in Fig. 10-5.

8 The minimum spacing is set in the initialization file of the program. It is editable by the user.

TUTORIAL Chapter 6

79

Design Sections will be created automatically. Fig. 10-6 shows an example of the Support Lines and the associated Design Strips. If the image does not appear, click on Display Design Sections button. This tool is accessible from the Support Line Result Scale Toolbar shown in Fig.10-7 below.

FIGURE 10-5 FEM PULL DOWN MENU

FIGURE 10-6 FLOOR SLAB SHOWING THE DESIGN STRIPS AND THE DESIGN SECTIONS

Chapter 6 TUTORIAL

80

FIGURE 10-7 SUPPORT LINE DESIGN TOOLBAR

11. Design/Code Check the Structure [13]

Click on the Design the “Design Section(s)” button from the FEM pull-down menu (Fig. 10-5) to calculate the design values and the associated reinforcement for each of the design sections shown.

During designing, the program automatically calculates the integral of the actions for each of the design sections (cuts) and applies the integral to the cross-sectional area of that section to determine the required reinforcement. During this stage, program does the code check and calculates the design values and the associated reinforcement for each of the load combinations and also calculates the envelope of all the load combinations.

12. Examine the Design [14] The next step is to view the design results and see whether the design is acceptable or not. The design moment (the integral value used for the computation of the reinforcement) for each of the support lines, as well as other actions, such as shear and axial forces can be viewed for each support line. Also the deflection, stress, precompression and balanced loading can be viewed for each support line. They can also be included in the reports that the program generates. We will now view one display variation of the design moments of the support lines in X-direction. This display is handled using the Support Line Result Scale Toolbar (Fig.10-7).

Click on the Results Display Settings tool ( ) to setup the item to be displayed for each support line. The window as shown in Fig.12-1 will open.

Select the load combination Envelope and the action Bending moment from the drop-down list and click OK.

Click on Display Design Section tool ( ) to turn the design sections off. Click on the Display Graphically tool ( ) to display the moment

diagram along each of the support lines. Click on Top-Front-Right View to see the structural in 3D.

Click on Perpendicular Projection tool ( ) to see the distribution normal to the slab.

TUTORIAL Chapter 6

81

Use the scaling tools ( ), if the distribution shown is not to scale.

Use the Display Max/Min Values ( ) to see the largest and smallest magnitudes of the moments.

FIGURE 12-1 RESULTS DISPLAY SETTINGS WINDOW

By now you should have obtained a diagram of moment distribution somewhat similar to Fig. 12-2.

FIGURE 12-2 DISTRIBUTION OF MOMENTS FOR DESIGN STRIPS IN X-DIRECTION

The reinforcement for each support line is calculated and reported. We will view the reinforcement and the design values of the upper support line (support line 1).

Chapter 6 TUTORIAL

82

Click on the upper design strip. Change in color indicates that the design strip was selected. Go to the results summary screen by clicking on the Show Design Summary

( ) option from the FEM pull-down menu. The result summary window with a toolbar as shown below (Fig.12-3) will open.

FIGURE 12-3 TOOLBAR OF DESIGN SUMMARY WINDOW

From the combo box at the top of the screen select Strength (Dead and

Live) Combination. Then click on the Moment Diagram button. A distribution, such as shown in Fig. 12-4, appears. This diagram shows the distribution of design moment of the support line selected. It is the moment of the entire tributary shown along the support line.

FIGURE 12-4 DISTRIBUTION OF DESIGN MOMENT IN DESIGN SUMMARY SCREEN

Click on the Summary Report ( ) tool to see the distribution of

reinforcement for the design strip. A diagram similar to Fig. 12-5 will appear. The diagram lists the top and bottom bars, for the loading combination we selected earlier (strength condition). To view the entire

TUTORIAL Chapter 6

83

reinforcement necessary for the design of the design strip, select the Envelope from the combo box of the toolbar.

FIGURE 12-5 DISTRIBUTION OF REINFORCEMENT FOR

UPPER SUPPORT LINE

From the combo box, select Envelope. Click on the Rebar Diagram button. The total area of reinforcement needed at each design section along the length of the support line will display, as shown in Fig. 12-6. This reinforcement is the envelope of all load cases specified by the user. In our case, it will be from the two strength load cases since there are no minimum reinforcement requirements of the code for MAT structure.

Chapter 6 TUTORIAL

84

FIGURE 12-6 ENVELOPE OF THE AREA OF REINFORCEMENT ALONG THE LENGTH OF THE DESIGN STRIP

After reviewing the result, if the design is acceptable to you, you can move forward to generate the structural documents such as Rebar drawing, PT drawing and calculation report. If not acceptable, modify structures or other parameters and design again.

13. Generation of Rebar Drawing

Next, we will create, view and edit the reinforcement drawing. From the FEM pull-down menu, click on Generate Rebar Drawing. The

program generates a reinforcement drawing similar to Fig. 13-1. Obviously, when using the SI system of units, the reinforcement will be expressed in the common practice of metric systems.

FIGURE 13-1 REBAR DRAWING SHOWING TOP AND BOTTOM REINFORCEMNT IN X-DIRECTION

If no rebar appears on the screen, do the following:

From the User Interface pull-down menu bring the Reinforcement Toolbar

on the screen (Fig.13-2).

FIGURE 13-2 REINFORCEMNT TOOLBAR

TUTORIAL Chapter 6

85

Click on Open Rebar Display Options tool ( ) to open the window as shown in Fig.13-3, and set the display as you want to be.

FIGURE 13-3 REBAR DISPLAY OPTION If the size of the text of rebar on the screen is not right, go to the Select/Set

View Items ( ) and change the size of the Rebar font.

Double click on one of the bars to open its property box. This allows you to modify the display, as well as other properties of the reinforcement. The extent of editing available to you depends on the configurations of your program.

Turn the rebar display off by clicking on Display/Hide Rebar ( ) You can export this rebar drawing to dwg/dxf format using Export option

under File menu.

14. Calculation Report

The program generates detailed professional quality reports of the design you performed. You have full control of the items and the size of the report, as well as its layout. For illustration purposes, we will generate a single sheet of tabular report. The tabular reports generated by the program are in rtf file format. They can be opened in your in-house word processing, viewed, edited and printed.

For tabular reports, we select the design section forces. Do the following:

Chapter 6 TUTORIAL

86

From Reports pull-down menu, select Single Default Reports/Tabular/Design Section Data/Design Section Forces Tabular report. This will bring up the window as shown in Fig. 14-1.

Select Strength (Dead and Live) case. A tabular report similar to the one shown below will appear.

FIGURE 14-1 DESIGN SECTION FORCES TEXT REPORT SELECTION WINDOW

154 DESIGN SECTION ACTIONS 154.20 DESIGN ACTIONS FOR AUTOMATICALLY GENERATED SECTIONS Load Combination: Strength (Dead and Live) Design Strip: Support Line 1 Design section Moment Shear Axial Torsion

k-ft k k k-ft 101000 -1.937 3.063 -0.063 -10.587 101001 -6.931 3.190 -0.051 -8.446 101002 -16.809 9.450 -0.042 -13.606 101003 -36.001 20.289 0.088 41.054 101004 -67.838 22.398 0.022 17.485 101005 -109.231 30.359 -0.107 24.178 101006 -157.498 33.470 -0.090 -23.777 102000 -120.981 -1.866 -52.560 -16.311 102001 -120.770 1.422 -52.639 11.774 102002 -94.794 119.735 -137.277 -3.690 102003 -285.225 116.799 -137.247 -8.685 102004 80.644 120.147 149.070 9.484 102005 117.154 -1.037 61.083 -26.047

TUTORIAL Chapter 6

87

102006 124.544 -6.014 61.116 -68.453 103000 167.724 37.900 0.010 -68.560 103001 120.557 29.631 0.010 -21.047 103002 77.290 29.641 0.010 -20.899 103003 48.854 16.313 -0.163 -107.315 103004 32.585 7.729 -0.237 -92.593 103005 28.726 -2.655 -0.087 -188.690 103006 23.228 1.457 -0.109 -93.840 104000 38.282 -7.257 0.067 -144.144 104001 -7.497 10.645 -0.088 171.723 104002 -23.624 3.714 -0.069 78.175 104003 -27.150 -0.728 -0.006 26.503 104004 -21.832 -2.577 -0.020 8.366 104005 -14.647 -2.107 -0.021 3.476 104006 -9.057 -1.191 -0.007 -8.052 104007 -3.193 -2.210 -0.000 -14.960 104008 -2.600 0.134 -0.000 -0.241 104009 -0.615 -0.444 -0.000 -1.467 104010 -0.051 -0.192 -0.000 -2.026

Design Strip: Support Line 2 Design section Moment Shear Axial Torsion

k-ft k k k-ft 201000 -0.030 4.390 0.063 -7.053 201001 -6.927 4.263 0.051 -5.382 201002 -17.011 11.290 0.042 -4.264 201003 -39.172 14.779 -0.088 16.130 201004 -66.830 20.270 -0.022 8.902 201005 -107.869 26.790 0.108 24.553 201006 -154.254 32.720 0.091 -0.765 202000 -115.544 -1.379 -54.329 -5.179 202001 -119.753 2.055 -54.250 0.638 202002 -92.450 116.597 -137.195 -2.387 202003 -280.080 115.330 -137.226 8.638 202004 86.528 118.228 145.347 29.053 202005 111.529 1.029 61.634 -7.052 202006 120.621 -6.453 61.602 48.556 203000 164.051 39.426 -0.010 43.329 203001 112.359 34.458 -0.010 20.658 203002 64.705 25.209 -0.011 82.013 203003 44.955 10.782 0.163 104.580 203004 30.044 10.313 0.237 111.858 203005 26.003 -1.337 0.087 85.176 203006 29.550 -1.788 0.109 100.761 204000 25.100 11.097 -0.067 -110.906 204001 -7.397 14.574 0.088 -188.796 204002 -24.831 4.299 0.069 -90.079 204003 -28.448 1.217 0.006 -48.578 204004 -24.271 -3.700 0.020 -1.170 204005 -15.557 -2.258 0.021 0.855 204006 -7.818 -2.933 0.007 5.634 204007 -2.407 -0.852 0.000 2.398 204008 -0.542 -1.273 0.000 6.674 204009 -0.219 1.197 0.000 -2.625

Chapter 6 TUTORIAL

88

204010 -0.124 -0.469 0.000 2.695 This brings us to the end of the analysis and design tutorial using the ADAPT-Builder MAT capabilities of the ADAPT software suite.

89

Chapter 7

ANALYTICAL BACKGROUND

ANALYTICAL BACKGROUND Chapter 7

91

This section provides information on several aspects of the analysis and design features of ADAPT-MAT.

7 OVERVIEW

ADAPT-MAT is a standalone computer program within the umbrella of ADAPT-Builder software platform. It has been entirely developed by the ADAPT’s team of structural engineers and software developers, who have been

7.1 STRUCTURAL MODELING

7.2 ANALYSIS

The analysis processor of ADAPT-MAT is based on the finite element formulation developed and implemented in Builder platform, with some modifications to cover the features that are specific to mat foundation. The program uses almost entirely well proportioned quadrilateral flat shell elements with bending and membrane degrees of freedom. Details of the formulation are given in the Floor-Pro manual and its references. Walls are also represented by the same type of shell elements.

Beams and columns are modeled as beam (stick) elements with six degrees of freedom at each node.

Unlike many other commercially available programs, complete compatibility of displacement is established over the entire foundation system and among all its components. For example grade beams bellow the foundations are modeled eccentric to the slab = as they appear in real life = but are solved with full compatibility of displacement at their interface with the slab (equal strains in beam stem and slab at common interface).

Post-tensioned tendons, where present, are discretized in segments associated with each shell element they traverse. When force calculation is invoked by you, the force along each tendon varies as passes from one shell element into the next. The advanced and unique features of ADAPT-MAT have become possible due to a finite element formulation specifically developed for analysis of complex concrete structures, including post-tensioning [Aalami, 2003?]

Chapter 7 ANALYTICAL BACKGROUND

92

7.3 DESIGN

The design involves (i) the calculation of “design values” (demand), (ii) the comparison with allowable limits of the building code you select, and (iii) provision of reinforcement, where applicable. The design values are determined in a manner similar to elevated slabs. The procedure is explained in detail in reference [PTI ??, ]. The important point to note is that for each design section the builder platform determines the design values from the equilibrium of the finite element nodes, as opposed to the common practice of using the integration of stresses along a cut at the section. As a result, accurate design values are obtained for relatively coarse finite element mesh [ADAPT-TN ???].

7.4 CREATION OF STURCTURAL DOCUMENTS

Reports The report generation and features are identical to floor-pro and are reported in FLOOR-Pro user manual [ADAPT, ??? ]

Soil Pressure

In addition to the values reported in floor pro, the program reports the distribution of soil pressure below a slab as indicated in Fig.???. The following in the interpretation and evaluation of soil pressure is noteworthy.

Figure ??? Soil Pressure

The raw data obtained from a finite element analysis, as shown in fig above, is the distribution of stress at “points” below the foundation slab. From a practical point of view, however a high or low value of soil pressure at a “point” does not reflect the likely response of the soil that is of interest to design engineer. For an engineering evaluation, when dealing with a reinforced concrete slab resting freely on soil, one considers the average pressure over a minimum area of design significance. For concrete slabs resting on common soil9 a minimum diameter four to five times the slab thickness should be considered. In other words, at the location of design check, the distribution of soil stress reported below the slab, should be integrated over a “design” significant area to determine the total force. The total force over the “design” patch when divided over the area of the patch will yield the design stress to be compared with the allowable soil pressure for the soil.

9 Bulk modulus 100 to 200 pci

ANALYTICAL BACKGROUND Chapter 7

93

Why superposition does not apply In the general case, the principle of superposition of solutions obtained for different load cases does not apply to mat foundation slabs. If there is likelihood of any separation of the slab from the soil. Even though the solutions obtained for the mat foundations are based on elastic material properties, the different amount of separation of soil from the mat between any two load cases creates a difference between the structural systems that carries the load in each of the two load cases. Once the structural systems become different, the superposition does not apply. The illustrative example given in Appendix ??? clarifies this concept.

95

Chapter 8

EXAMPLES

EXAMPLES Chapter 8

97

The one used for verification Example 1 The one in the manual file (non-prestressed) A prestressed example Grade beam example

99

Chapter 9

SAMPLE CALCULATION REPORT

SAMPLE CALCULATION REPORT Chapter 9

101

9 OVERVIEW

103

APPENDIX

APPENDIX

105

NOTATION

REFERENCES

adapt mat-foundation 2010 manual

Documents