3D-Dynamic design for reinforced versus prestress concrete for Al-Huriya building

 Prepared by

Nizar Abed Al-Majeed SalamehMohamed Khaled Abu-Al Huda    

Supervisor Dr. Imad Al-Qasem

CHAPTER ONEINTROUCTION

The project is a structural analysis and 3D-Dynamic design of an office building in Ramallah city, known as AL-Huriya, which consists of a seven stories, with 3.5 height except the first floor with 4m story height.

The building will be first designed under a static load, after that we will study the building for dynamic , finally a prestress concrete will be used to design the building to compare it with the reinforcement concrete, to conclude many factors that should be taken into consideration in designing any structure. These include economic factors , durability and the safety of its inhabitants.

System Part F’c fy

Reinforced Concrete Slab 250 kg/cm2 4200 kg/cm2

Beams 250 kg/cm2 4200 kg/cm2

Columns 500 kg/cm2 4200 kg/cm2

Footings 250 , 500 kg/cm2 4200 kg’cm2

Prestress Concrete slab 6000Psi 243Ksi

Columns 500 kg/cm2 4200 kg/cm2

Footings 250 , 500 kg/cm2 4200 kg/cm2

Materials

Live load 0.4ton/m2

Super imposed load 0.3ton/m2

Loads

CHAPTER TWOSLAB

 

One way solid slab is used only as slab system

Use slab thickness of 17cm , according to deflection requirement

In design phase of the slab, there are two strip(1m) taken as a model.

Wu=1.51

15@3.75m

6@3.75m

Wu=1.51

Strip I

Strip II

Loads distribution

Strip I

Use 4Ф12mm for negative and positive moment

Moment distribution

Strip II

CHAPTER THREEBEAMS

Beams in this part of the project will be designed using reactions from beam model in SAP2000.

The girder system is used to design the building, and all of the beams are dropped; multi span and large space beams are used in all floors.

The system of the building consist of a four beams group (B1, B2, B3, B4)And a two group of girders (G1, G2).

Design for Moment

Final ResultsPositive Moment Negative Moment

Exterior spans Interior span Interior supportsBeams Dimensions Mn Ρ As Mn ρ As Mn ρ As

B1 30x80 65.61 0.0102 25.45 1.31 0.0033 7.62 58.76 0.0091 22.90

B2 50x90 168.82 0.0112 58.88 3.44 0.0033 14.70 152.17 0.0113 49.06

B3 50x90 183.76 0.0141 63.78 - - - 129.34 0.0094 44.16

B4 60x100 263.26 0.0133 78.50 - - - - - -

Final Results

Positive Moment Negative Moment

Exterior spans 1st interior spans 2nd interior spans 1st interior supports 2nd interior supports

Girders Dimensions Mn ρ As Mn ρ As Mn ρ As Mn ρ As Mn ρ As

G1 50x90 164.24 0.0123 53.97 51.99 .0036 19.63 117.93 .0085 39.25 163.62 0.0123 53.97 141.8 0.0104 40.06

G2 90x100 384.78 0.0129 112.54 219.22 .0069 64.31 62.57 .0033 32.15 411.27 0.0141 120.58 209.44 0.0066 56.27

Moment Design

Parameter Dimensions Mn As Vn Vc Vs Av S

Units cm ton.m cm2 ton ton ton cm2 cm

Shear Design

Design for Shear

Final Results Exterior spans Interior span

Beams Dimensions Vn Vc Vs Av S Vn Vc Vs Av S

B1 30x80 31.746 18.855 12.890 1.57 35 21.250 18.855 2.395 1.57 35

B2 50x90 80.10 35.61 44.49 3.14 25 54 35.61 18.39 3.14 40

B3 50x90 77.22 35.61 41.61 3.14 25 25.10 35.61 14.875 3.14 40

B4 60x100 69.69 47.76 21.43 3.14 45 - - - - -

Final Results Exterior spans 1st interior spans 2nd interior span

Girders Dimensions

Vn Vc Vs Av S Vn Vc Vs Av S Vn Vc Vs Av S

G1 50x90 93.49

35.61 57.88

3.14

20 75.44

35.61

39.83

3.14

25 92.26

35.61

56.65

3.14 20

G2 90x100 229.1

71.64 157.4

3.14

5 202.6

71.64

131 3.14

5 99.52

71.64

27.88

3.14 45

Final Results

For positive moment (span) Negative moment (support)

Beam Exterior 1st interior 2nd interior 1st interior 2nd interior

B1 10Φ18 3Φ18 - 9Φ18 -

B2 12Φ25 3Φ25 - 10Φ25 -

B3 13Φ25 - - 9Φ25 -

B4 16Φ25 - - - -

G1 11Φ25 4Φ25 8Φ25 11Φ25 10Φ25

G2 14Φ32 8Φ32 4Φ32 15Φ32 7Φ32

CHAPTER FOURCOLUMNS

sixteen columns having a rectangular section, and eight columns having a circular section, will be designed.

All the columns in this project are classified into two groups depending on the ultimate axial load and the shape.

The ultimate axial load on each column is from the Reaction of beams

Columns number Ultimate load(ton) Ultimate loads from seven stories(ton)

C1 144.24 1009.68C2 60.96 426.72C3 179.18 1254.26C4 452.71 3168.97C5 287.65 2013.55

Group (1) C1,C2,C3 Rectangular

Group (2) C4,C5 Circular

Summary of result

Group Pu(ton)

Dimensions(h*b)(cm) spirally (D)(cm)

ρ As(cm2) # of bars Shear reinforcement

I 1254.26 100*50 0.0152 76.04 16 Φ25mm 4 Φ10mm/30cm

II 3168.97 Spiral, D=100 0.0206 267.41 34 Φ32mm Φ10mm(spirally)

Final Results

CHAPTER FIVEFOOTING

In this chapter the footing will be designed, all footings in this part of the project will be isolated (single) footings.

The design will depend on the total axial load carried by each column.

GroupID

Columnsincluded

Loads (ton)

Dead load Live load

F1 C1,C2,C3 726 203

F2 C4,C5 1698 504

The footings are classified into two groups

Flexure Design  

X-Y Direction Steel Design  Mu = 107.12 ton.m

   ρ = 0.0023  

As = 25.62 cm2

As min = 21.6 cm2

   Use As = 25.62 cm2

   

Bar Diameter 25 mm   

# of Bars Needed 6     

Spacing 16.67 cm

Group F1 Design

Use

Main Steel 6ф25/ m

Or 1ф25/16cm

Shrinkage Steel 5ф25/20cm

Flexure Design  X-Y Direction Steel Design  

Mu = 274.80 ton.m   

ρ = 0.0025  As = 43.24 cm2

As min = 32.4 cm2

   Use As = 43.24 cm2

   

Bar Diameter 32 mm   

# of Bars Needed 6     

Spacing 16.67 cm

Group F2 Design

Use

Main Steel 6ф32/ m

Or 1ф32/16cm

Shrinkage Steel 5ф32/20cm

FootingID

Footing Dimentions (m) Bottom Steel Top Steel

Width Length Thickness Long dir. Short dir. Long dir. Short dir.

F1 4.6 5.1 1.2 6ф25/ m 6ф25/ m 3ф25/20cm 3ф25/20cm

F2 7.45 7.45 1.8 6ф32/ m  6ф32/ m  3ф32/20cm 3ф32/20cm

Final Results

Ground Beam Design

Dimensions Bottom & Top Steel

G.B Width(m) Depth(m) exterior interior Support

G.B I 0.4 0.7 7Ф20 5ф18 7Ф25

G.B II 0.5 0.75 9Ф25 5ф18 10ф25

Final Result

Static vs. Dynamic analysis

Our representative element will be the bending moment at the mid span of the interior span in the 2nd frame for each model.

We will take model for three stories , seven stories and ten stories then read the moment due to dead load and live load.

Moment due Three Stories

Seven Stories Ten Stories Average

Live Load 9.7 9.52 9.72 9.54 9.82 9.66

Dead Load 25.38 24.93 25.46 24.99 25.77 25.31

As the result shows, the common practice is correct for interior floors in static analysis

Static analysis

Columns Comparison

Our representative element will be the axial force due to live load .

We will take model for three stories , seven stories and ten stories ,then read the axial force for corner , edge and interior columns in the bottom of each model.

SAP 2000 Analysis Results

Axial Force For

Three Stories Seven Stories Ten Stories

Corner Column 43.32 ton 105.98 ton 157.76 ton

Edge Column 86.68 ton 207.98 ton 302.27 ton

Interior Column 241.98 ton 485.37 ton 676.77 ton

Internal Col.

Edge Col.

Corner Col.

Tributary area

Tributary area Results

Live Load = 0.4 ton/m2

Axial Force For Three Stories Seven Stories Ten Stories

Corner Column 43.03 ton 100.41 ton 143.44 ton

Edge Column 93.66 ton 218.53 ton 312.19 ton

Interior Column 187.31 ton 437.06 ton 624.38 ton

Using SAP 2000 Software

# of Stories T(sec) Mass Participation Ratio Direction

One 0.534228 0.995042 X-Direction

0.435512 0.996652 Y-Direction

Three1.099129 0.965566 X-Direction

0.882423 0.970756 Y-Direction

Seven2.092426 0.932716 X-Direction

1.65703 0.938386 Y-Direction

Ten2.806996 0.913832 X-Direction

2.21439 0.91895 Y-Direction

Seven+Elcento

2.092426 0.932716 X-Direction

1.65709 0.938386 Y-Direction

Dynamic Analysis

CHAPTER SEVENPRESTRESS CONCRETE

Prestress concrete is not a new concept, it’s backing to 1872. (Jackson), an engineer from California, patented prestressing system that used a tie rod to construct beams or arches from individual blocks.The most practical development in prestressed concrete occurred from (1920 – 1960).

Introduction

We will design the prestress building for gravity loads only, and the punching shear excluded from this study.

(ACI units is used)

Material properties and loads

Material properties:-f’c =6000 Psi f’c i = 4200 Psffpu = 270 Ksi fpy =243 Ksifpe= 159 Ksi fy = 60000 PsiUse strands = 1.0 inch. Pe= 257597 Ib

Loads:-live load (LL) = 80 PsfSuper Imposed Load (SID) = 60 Psf

Slab thickness = Slab thickness = = 13.13 inches.

Take slab thickness = 13.5 inches.

 

Check stresses:-

1) check allowable stresses for the prestressing force and the slab own weight.

2) Check the ultimate strength .

Slab Design for prestress system

Columns design for Prestress system

Sixteen columns having a rectangular section, and eight columns having a circular section, will be designed.

All the columns in this project are classified into two groups depending on the ultimate axial load and the shape.

The ultimate axial load on each column is from the Tributary area.

Columns number Ultimate loads from seven stories(ton)C1 606.06C2 1119.30C3 1210.70C4 1725.00C5 2240.00

Group (1) C1,C2,C3

Group (2) C4,C5

s

Summary of result

GroupDimensions(h*b)(cm)

spirally (D)(cm)ρ As(cm2) # of bars Shear reinforcement

I 95*55 0.0123 28.16 8 Φ22mm 4 Φ10mm/25cm

II Spiral, D=900.0142

3128.68 16 Φ32mm Φ10mm(spirally)

Final Results

Footing design for prestress system

All footings in this part of the project will be isolated (single) footings.The design will depend on the total axial load carried by each column.

The footings are classified into two groups

GroupID

Columnsincluded

Loads (ton)

Dead load Live load

F1 C1,C2,C3 694 236

F2 C4,C5 1284 437

Group F1 Design

Flexure Design  

X-Y Direction Steel Design  

Mu = 108.34 ton.m

   

ρ = 0.0020  

As = 24.34 cm2

As min = 23.4 cm2

   

Use As = 24.34 cm2

   

Bar Diameter 25 mm

   

# of Bars Needed 5  

   

Spacing 20 cm

Use

Main Steel 5ф25/ m

Or 1ф25/20cm

Shrinkage Steel 5ф25/20Cm

Group F2 Design

Flexure Design  

X-Y Direction Steel Design  

Mu = 222.97 ton.m

   

ρ = 0.0031  

As = 42.71 cm2

As min = 27 cm2

   

Use As = 42.71 cm2

   

Bar Diameter 28 mm

   

# of Bars Needed 7  

   

Spacing 14.29 cm

Use

Main Steel 7ф28/ m

Or 1ф28/14cm

Shrinkage Steel 5ф28/20cm

FootingID

Footing Dimentions (m) Bottom Steel Top Steel

Width Length Thickness Long dir. Short dir. Long dir. Short dir.

F1 4.65 5.05 1.3 5ф25/ m 5ф25/ m3ф25/20c

m3ф25/20c

m

F2 6.6 6.6 1.5 7ф28/ m 7ф28/ m3ф28/20c

m3ф28/20c

m

Final Results