midas civil training_0220-edit-final.pdf

Sharing Knowledge, Gaining Experience, Making Difference

Organized By MIDASoft, Inc.

MIDAS e-Learning Courses

Bridging Your Innovations to Realities

Network Tied Arch Modeling, Analysis & Design

midas Civil Bridging Your Innovations to Realities

The following will be contents of this training

1. Introduction

- Summary of In-depth Discussion Session

- midas Civil GUI

-Project Information

3. Analysis and Design

- Moving Load

- Final Stage Analysis

- Unknown Load Factors

- Hanger Force Tuning

- Set up for Construction Stage

- Construction Stage Analysis

- Time History Analysis

- Hanger Loss

3

Contents

2. Modeling

- Unit Setting

- Materials & Sections

- Geometry: Arch, Hanger Arrangements, Tie, Wind Braces

- Boundaries & Loads


• Summary of in-depth discussion session:

• Analysis and design considerations

• Construction and final stage analysis

• midas Civil’s functions:

• Unknown load factor

• Cable load tuning

• Moving load tracer

• midas Civil Graphic User Interface (GUI)

• Project information

Introduction

4


Summary of in-depth discussion

5

• Hanger forces at different construction stages

2. Construction Stage Lack of Fit force

• Nonlinear behavior of cables

• Temporary supports situation

Design of Network Tied Arch

1. Final Stage Moving Load Tracer

Hanger Force Adjustment

• Calculate cable forces & cable force tuning

• Correct geometry

• Critical live load

• Extraordinary Loads (accidental hanger loss)

• Unknown Load Factor

Optimization problem

influence matrix

• Cable Tuning

• Time History Analysis


Midas Civil graphic user interface

6


Project information

60 ft

300 ft

Bridge Type: Network Tied Arch

• Bridge Length: 300 ft

• Arch Height : 60 ft

• Width : 30 ft

• Number of Lanes : 2

7


Network Tied Arch bridge need to be studied in two different stages, Construction stage and

Final stage, so we need two model files for each stage.

We start with Final stage model and apply all the ultimate static loads to the structure and run

a linear static analysis. The main purpose of this stage is to find optimized pretensioning

forces in each hanger for the best performance of the bridge.

The second part is investigation of bridge’s behavior during erection. In this stage the hanger

forces obtained from the first model will be used as initial pretensioning force of hangers

during construction stages, and responses of the bridge will be monitored. The model used in

this stage contains 42 construction stages starting from tie and arch erection with help of

temporary supports and ending by installing hangers and remove the temporary supports.

Project information

8


Part 1

• Unit setting

• Define material and sections

• Geometry

• Arch

• Hangers

• Cross beams

• Longitudinal girders

• Structure Alignment

• Braces

Modeling-part 1

9


Units setting

File New Project

Tools Unit System

1. Length ft

2. Force kips

3. Click OK

10


Materials

Properties Material Properties

1. Click Add

2. Type of Design Steel

3. Name A501

4. Standard ASTM09(S)

5. DB A501

6. Click OK

Similarly Define Grade C5000 Material

in Type of Design as Concrete

1

11

6

5

3

4 2


Properties Section Properties

1. Click Add

2. Type I section

3. Name Arch

4. Select User Type

5. Enter Parameters as Shown

6. Click OK

Similarly Define Sections: W24X250,

W10X22, S24X121and cable section

with diameter .16feet

Properties Thickness

Define Thickness of .5 feet

12

Sections

1

4

2

3

6

5


Create Node

13

Geometry modeling

Node/Element Create Nodes

1. Enter the following coordinates:

(0,0,0), (300, 0, 0), (150, 0, 60) (-75, 0 ,-300)

Create Element

Node/Element Create Elements

1. Material 1: A501

2. Section 2: Tie

3. Click on Nodal Connectivity box to turn green

4. Select nodes 1 and 2 by clicking

1

2

3

4


14

Arch

Create Arch

Node/Element Create Line Element on Curve

1. Select Arc by 3 points

2. Material 1: A501

3. Section 1: Arch

4. Number: 16

5. Select corresponding nodes from model view

as following

P1: Node 1

P2: Node 3

P3: Node 2

1

2

3

4

5


15

Hanger arrangement

Create Hangers


1. Element Type: Tension Only/Hook/Cable

2. Material 1: A501

3. Section 5: cable

4. Click on Nodal Connectivity box to turn green

5. Connect node 4 to all nodes on the Arch (5 to

18)

6. Select all elements and node below the Tie and

delete them

1

2

3

5

4 6


16

Hangers

Mirror the hangers frame

Node/Element Elements Mirror

1. Select all hangers

2. Mode: copy

3. Reflection: y-z plane, x=150 ft

4. Apply

3

2

4


17

Hangers

Intersect hangers & tie

Node/Element Intersectt

1. Select tie elements

2. Apply

1

2


18

Structure alignment

Rotate Structure

Node/Element Elements Rotate

1. Select entire structure

2. Mode: move

3. Angle of Rotation: -10

4. Axis of Rotation: last option (2 points)

5. Select nodes 1 and 2 respectively or enter

coordinates:

1st point: (0, 0, 0)

2nd point: (300, 0, 0)

3

2

4

5

10˚


19

Arch

Mirror the network frame

Node/Element Elements Rotate

1. Select entire structure

2. Mode: copy

3. Reflection: z-x plane, y=15 ft

4. Apply 3

2

4


20

Cross beams

Node/Element Extrude

1. Select Nodes 1, 2, 21, 24, 26, 28,

30, 36, 39

2. Material 1. A501

3. Section 3: Tie

4. Dx,dy,dz 0, 5, 0

5. Number of times 6

6. Click -> Apply

It will create one more node

3

4

5

2


21

Longitudinal girders

Create Longitudinal girders


1. Material 1: A501

2. Section 3: Girder

3. Create 5 longitudinal girders by connecting

corresponding nodes of cross beams at two

ends


22

Wind brace

Create wind braces


1. Material 1: A501

2. Section 4: Braces

3. Create wind braces


Part 2: this model will be used for Final stage analysis

• Boundary conditions

• Groups for construction stages (structure, boundary and load groups)

• Abutments

• Loads

• Static load cases

• Self weight

• Superimposed dead load

• Pretensioning force of hangers

• Moving load

Modeling-part 2 (Final Stage)


Group Tab ( Tree Menu)

1. Define the Groups for

- Structure: Deck Stage 1 to 4,

Arch Stage 1 to 5, Hanger 1 to 30,

Temp Restrain 1 to 4, Lack of Fit

(all hangers), cross beams

- Boundary: End Supports, Temp

Supports 1 to 4

- Load Group: Self Weight , SDL,

Pretension 1 to 30

24

Groups for construction staging


Boundary Define Supports

1. Select Nodes at the left and the

right end of the bridge

2. Boundary Group Name End

Supports

3. Select Dall

4. Click Apply

25

Abutments

2

1

1

3

4


Load Static Loads Static Load

Cases

1. Name Self Weight

2. Type Dead Load

3. Click Add

Similarly Define SDL with Type Dead

Load and Pretension 1 to 30 with

type Prestress (PS)

26

Static load cases

1

2

3


Load Static Loads Self Weight

1. Load Case Name Self Weight

2. Load Group Name Self Weight

3. Z -1

4. Click Add

27

Self weight

1

2

3


Load Static Loads Element

1. Load Case Name SDL

2. Load Group Name SDL

3. w -70 lb/in

4. Select all longitudinal girders (tie)

5. Click Apply

28

Superimposed dead load

1

2

3

4


Load Temp./Prestress Pretension Loads

1. Load Case Name Prestress 1

2. Load Group Name Prestress 1

3. Prestress Load: 1 lb

4. Select 1st hangers from left (group: Hanger 1)

5. Click Apply

6. Repeat the process for all hanger groups

29

Pretensioning Load

1

2

3 4

5

Hanger 1

Hanger 2

Hanger 5


30

Moving Load

Load Moving load

1. Select AASHTO-LRFD

2. Click Traffic Line Lanes

3. Add

4. Name: Lane 1

5. Eccentricity: -7.5 ft

6. Wheel Spacing: 6 ft

7. Vehicular load distribution: select

cross beam group

8. Select by 2 points

9. Select nodes 1 and 2

10. Apply

11. Repeat for Lane 2 with

eccentricity of -22.5


31

Moving Load

Load> Moving Load Analysis Data> Moving Load case.

5. Enter a Load case name: MVL

6. Check or modify Multiple Presence Factor.

7.Select loading effect for sub load case as Independent .

8. Add Sub-Load case.

9. Select one of the vehicles..

10. Scale factor as 1, and min. number of loaded lane as 1 and max. as 2.

11. Select lanes L1 and L2.

12. Click OK.

13. Similarly create load case for HL-93 Tandem Vehicle.

3

Load> Moving Load Analysis Data> Vehicles.

1. Click Add Standard

2. Click on Vehicle load type

3. Select HL-93 TRK as first vehicle load type., DLA = 33%,Click Apply

4. Select HL-93 TDM as second vehicle load type. Click OK

8

5

6

7

9

11

10

12


Moving Load

• Moving load tracer find critical live load configuration

• Convert to static load

Final Stage Analysis

• Unknown Load factors

• Hanger force tuning

Construction Stage Analysis

• Geometry nonlinearity

• Lack of Fit force

Time History Analysis

• Hanger loss

Analysis


33

Run analysis 1: Final Stage


34

Results: Moving Load Tracer

Results Moving Load Moving Load Tracer Beam Force/Moment

1. Moving load case: Min MLC1

2. Element: 81

3. Apply: the vehicle arrangement that causes maximum negative bending moment will be shown

4. Click Write Min/max Load to file to save this load arrangement as a static load


35

Load combination

Results Load Combination

1. Create a load combination which

have all load cases (SW, SDL,

Pretensions 1~30) with factor 1.

2. Name: LCB

3. Select Self Weight, Factor: 1

4. Repeat for all load cases


36

Unknown Load Factor

Results Bridge Cable Control

Unknown Load Factor

1. Add New

2. Name: Hanger forces

3. Load Combination: Mid Span

4. Add Constraints

5. Name: Deck 131

6. Displacement

7. Node ID: 131

8. Component: Dz

9. Select Inequality

10. Upper and lower bound: 0.75 & -0.75

11.Repeat the process for Nodes 132 to 137

The static analysis is performed on final stage model file. Initially a unit pretension force is applied on all hangers, in this stage,

after static analysis, we are going to use Unknown Load Factor function to find required pretensioned load in each hanger for

certain constrains.


37

Unknown Load Factor

1. Load Comb: LCB

2. Square

3. Both

4. Check all Pretension load cases as

Unknown

5. Select all Constraints

6. Click get Unknown Load Factors


38

Hanger forces

Factors are calculated for each

hanger. This factor is the

required pretensioning force to

satisfy previously defined

constraints. To generate the

corresponding load

combination:

1. Click Make Load

Combination


3. Ok

4. Influence Matrix could be

extracted by selecting

Influence Matrix.

5. Ok


39

Hanger forces

The load factors, which are required pretensioning forces to be applied to each hanger

was calculated and a new load combination is created and the results could be checked

under this load combination.

Now the effect of change in pretensioning level of each hanger could be investigated by

using Cable Tuning function. The effect of such change on structure response could be

monitors as well.

The pretensioning loads obtained at this step, will be used for construction stages analysis.


40

Hanger force tuning

Results Bridge Cable Control

Cable Force Tuning

1. Load Combination: Hanger force


3. Click to generate new results

4. Name: Deck moment

5. Group: Deck stage 4

6. Type: Beam force, MY

7. x-Axix: +DX, Element

8. Add

9. Close

10. By changing in level of

pretensioning of each hanger,

bending moment changes

11. Save load combination as a new

combination with all the changes


this model will be used for Construction stage analysis

• Boundary conditions

Temporary supports

• Construction Stages set up

Define stages

CS analysis control data

• Loads:

Update pretensioning force of hangers (obtained from Final Stage Analysis)

In this stage, use the same model just add 42 construction stages, temporary supports (used for erection) and

apply pretensioning forces obtained from the previous part.

New set up for construction stages (modeling-part 3)


Boundary Define Supports

1. Select Nodes at the 1st cross

beams from the left and support

2. Boundary Group Name Temp

Supports1

3. Select Dz

4. Click Apply

Similarly define supports for nodes

at other cross beams by names

Temp supports 2 and 3 as the

group

42

Temporary supports

1 2

3

4

1

1


1. Right click on Pretensioning Load and select

Tables

2. Update all prestressing by corresponding

force (factors)

3. Data could be arranged in Excel and then

copied to the table

43

Update pretensioning forces

Unit pretensioning forces of hanger (which

defined in the first model) should be updated

and replaced by factored obtained previously

from Unknown Load Factors function


44

Define stages

Load Construction Stage

1. Generate

2. Name: Construction Stage

3. Suffix: 1 to 42

4. Ok

5. Change the names to:

Deck 1 ~ 4

Arch 1 ~ 5

Hanger 1 ~ 30

Remove Falsework 1 ~ 3


Construction stage analysis control data


46

Run analysis 2: Construction Stage


Results: Lack of Fit Force

Results Results Table Construction Stage Lack of Fit Force Truss

Sharing Knowledge, Gaining Experience, Making Difference

Organized By MIDASoft, Inc.

Thank You

Pouya Banibayat, PhD

[email protected]

646-852-9289

midas civil training_0220-edit-final.pdf

Documents

final stage model

realities network

realities project information

hanger forces

realities units

arch modeling

arch erection

ft arch height