bridge design using SAP

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Analysis and Design of Highway Super structure Bridge

Advisor: Dr. Bilal El Ariss

Name : ID :

Awad Mahfoudh Ba Obaid 200501233Hussain Mahmod Al braiki 200602670Salim Ibrahim Ba Saeed 200608514Salem Abdullah Fadaaq 200501514Suhail Mohamed Al Amri 200416287

Spring Semester 2011

Graduation Projects Unit

Graduation Project (II)

• Introduction

• Objectives

• Summary of GP (1)

• Background Theory

• Analysis & Design

• Economical , Environmental & Contemporary Issues

• Conclusion

Outline

Introduction

Development of Abu Dhabi has become a place full of shopping mall and luxury building, hotels.

Development increases the population of Abu Dhabi.

Population growth causes problems in the infrastructural.

Major infrastructural problem is the traffic jam.

The bridge is constructed to link many other major roads to the City of Abu Dhabi.

Problem Statemen

Objectives

• The main objective of this graduation project is to

recommend and present different bridge alternative

Bridges. Analysis will be conducted for the different bridge

alternatives. Then, those different bridge alternatives will

be designed according to our analysis.

Summary of GP1

The pier cap is a structural element that transfers

the loads carried by the superstructure elements to

the substructure elements, located at the junction of

two spans.

Literature ReviewPier Caps

Single column (Hammerhead).

Multi-column or pile bent.

Solid Wall.

There are different types of pier caps, the following are the most common types:

Literature ReviewPier Caps

The selection of the pier type depends on many factors,

such as :

1. Required load capacity.

2. Superstructure Geometry.

3. Site conditions.

4. Cost Consideration.

5. 5. Aesthetics.

Pier Cap Dead Load Analysis Process

Total Dead loads coming from girders have been

considered as point loads (concentrated loads on the pier

In this case, there have been a total of 9 concentrated

loads imposed on the cap (since we have 8 girders).

Dead Load Analysis

We will design on the Maximum Load from girder = 2380.03 kN

Support Load (kN)

1 827.6

2 2380.03

3 2023.05

4 2120.4

5 2087

6 2120.4

7 2023.05

8 2380.03

9 827.6

SAP2000 Dead Load Analysis

Next, take the maximum reactions. Then entered as point concentrated loads

SAP2000 Dead Load Analysis

Finally, Bending moments are determined for the maximum critical load effects

Live Load Configurations

Live Load Study Cases

Case (1): On the middle

P = 284.7 KNW = 345.78 KN/m

According to the AASHTO standards, there are different live load scenarios that should be studied in order to obtain the maximum possible live load:

Case (2): Full Shift Left

Case (1): One on the middle• R1= 0• R2= 0• R3= 7.845 KN• R4= 838.7 KN• R5= 838.7 KN• R6= 7.845 KN• R7= 0• R8= 0

Case (2): Full Shift Left• R1= 1183.14 KN• R2= 1116.7 KN• R3= 1243.2 KN• R4= 1899 KN• R5= 1251.1 KN• R6= 1212.3 KN• R7= 760 KN• R8= 1636.6 KN

Live Load Cases Result

Load Cases G1 G2 G3 G4 G5 G6 G7 G8

1 1183.14

1116.7

1243.2

1251.1

1212.3

759.718

1636.6

2 0 0 7.845

760.1 0 0 0

Max. Load (kN)

1183.14

1116.7

1243.2

1251.1

1212.3

759.718

1636.6

Take the maximum reaction from cases. Then entered in the SAP2000 as concentrated load

Live Load

Finally, Bending moments are determined for the maximum critical live load effects

Ultimate Moment of Pier cap

Moment Location

Moment form Dead Load (KN.m)

Moment from Live Load (KN.m)

Ultimate Moment (KN.m)

Span 1 8041.71 4109.21 17243.255Middle Pier -13474.53 -7170.1 -29390.838

Span 2 8041.71 3989.76 17034.2175

Bridge component

Design

Bridge Girder

Frame 7Frame 1 Frame 6Frame 2 Frame 5Frame 3 Frame 4 Frame 8

Abutment 2Pier 1 Pier 6Pier 2 Pier 5Pier 3 Pier 4 Pier 7

Frame Positive Ultimate Moment (kN.m)

Pier cap Negative Ultimate Moment (kN.m)

1 15407.1 1 -192592 8723.79 2 -189083 11265.6 3 -135294 10604.7 4 -149765 10604.7 5 -135296 11265.6 6 -189087 8723.79 7 -192598 15407.1 Max -19259

Max 15407.09

• Girder ultimate negative moments values:

Analysis Data

Bridge Girder Design Concept

Main target is to determine the location of the neutral axis.

Two cases: Case 1:

N.A falls in the flange (a ≤ hf) Section above N.A is rectangular

Case 2:

N.A falls in the flange (a > hf) Compressed concrete above N.A is NOT

rectangular. Divide compressed concrete Above N.A into rectangular parts.

Compare the values of Mu & Mflange if:

Mu < Mflange a < hf

Mu > Mflange a > hf

Where:

Mu = Moment from applied forces

Mflange = Moment carried by flange.

R-Section

STEP 1: Assume bar size.

STEP 2: Assume cover.

STEP 3: Compute depth of steel reinforcement ( d ).

STEP 4: Determine ( ρ ) from Tables or ACI Equation.

STEP 5: Ensure that ρmin ≤ ρ ≤ ρmax.

STEP 6: Determine As.

Design procedure

Calculations

Girder Design Steps:

Bottom Steel Reinforcements.

Top Steel Reinforcements.

Girder Design

Reinforcement Calculations

mmdmmdmmC

MpafMpafc

431040

42035'

Assume Bar size # 43

mmdCoverhd

ddCCover bsc

2428722500

725.71243

1040Cover

Bottom steel

Based on the above result case one procedure will be followed.

fflangeu

flange

ffcflange

mkNmmNXM

hdbhfM

.51533.508.10153.52

7502428*)1250*2500*35*85.0(

2*)85.0(

.09.54071

Reinforcement CalculationsBottom

3231.22428*1250*9.01009.15407

005766.0

35*85.0323.2*2

35*85.0

0035.0

0035.0420*435

0033.0420

ofGreater

fofGreater

0035.0

0035.0420*435

0033.0420

ofGreater

fofGreater

815.035*007.006.1

30007.006.13085.0

MPafforfMPaffor

025.0420600

600420

35*815.0*85.0)75.0(

60060085.0

)75.0('

CMax ff

Max min

bars 31bars 1.121452

17499.523bar one of areasection cross

A bars ofNumber

17499.523

2428*1250*0035.0

So according to the area of steel obtained, we choose to take 13 bars # 43

• As =13 bars #43 for each meter ,

• From table bmin =1174mm < bactual =1250

• So, we need one layer.

Reinforcement CalculationsTopsteel

Girder reinforcement

Postive ultimate moment (kN.m)

Number of steel bars

Pier cap

Negative ultimate moment (kN.m)

Number of steel bars

1 15407.1 13# 43 1 -19259 16 # 43

2 8723.79 7 # 43 2 -18908 15 # 43

3 11265.6 9# 43 3 -13529 12 # 43

4 10604.7 9# 43 4 -14976 12 # 43

5 10604.7 9# 43 5 -13529 12 # 43

6 11265.6 9# 43 6 -18908 15 # 43

7 8723.79 7 # 43 7 -19259 16 # 43

8 15407.1 13# 43

Reinforcement

The failure of reinforced concrete beams in shear is

quite different from their failure in bending.

Shear failure occur suddenly with little or no advance

warning.

Girder Shear

ReinforcementGirder Shear

Vu= 1271 KN Ø for shear = 0.75 We found that ØVc/2 = 673.31 < Vu= 1271 KN < ØVc=1346.63

KN So we need minimum strips We choose stirrups number 16 with max allowed spacingSmax =smaller of: 600mm

or 0.5d=0.5 x 2428=1214mm or

Choose Smax=600mm=60cm

ReinforcementGirder Shear

Dead Load Analysis Process

Total Dead loads coming from girders have been

considered as point loads (concentrated loads on the

pier cap).

In this case, there have been a total of 9 concentrated

loads imposed on the cap (since we have 8 girders).

Pier caps

According to reinforcement concrete (RC)

design concept, the design of bridge pier

caps follows the rectangular section design

method which used in slab design.

Concept & theory Pier caps

Design

Pier cap design fc

’ = 35 MPa fy = 420 MPa Cc=50 mm

db=57 mm

ds= 10 mm According to the ACI codes:

ρ = 0.85 (fc’/ fy) x [1-(1-(2Rn / 0.85 fc

’)0.5]

Rn = Mu/φ bd2

As=ρbd

Reinforcement Calculations

Mu = 17243.255KN.m = 17243.255x 106 N.mm

Cover= Cc+db+ds= 50+57+10= 88.5 mm =90 mm

d=h-cover=2550-88.5= 2461.5 mm

Rn = 17243.255x106 / (0.9 x 1000 x 2461.5 2)= 3.166

ρ = 0.85 (35/ 420) x [1-(1-(2x3.066 / 0.85x 35)0.5] = 0.00798

Bottom steel

From ACI Table the ρmax= 0.0216, and ρmin 0.0035

since the ρ = 0.00719 is between the extremes

ρmax<ρ < ρmin , ok (ρ = 0.00719)

As=ρbd=0.00797 x 1000 x 2461.5 = 19651.67 mm2

Steel Reinforcement

Moment Location

Ultimate Moment (KN.m)

As (mm2)

No. of bars

Span 1 17243.255 19300 8#57Middle Pier -29390.838 34452.964 15 #57

Span 2 17034.2175 19050.328 8#57

Pier cap

Negative shear Positive shear

span 1 -7587.37 -middle pier -12641.7 13840

span 2 - 7667.12

Shear Design Calculation Pier cap

We will design on the ultimate shear

Vu= 13840 KN

In our case we found that Vu ≥ ØVc , so we will need stirrups

So we will use

Spacing limit :-

Alternative design

Present the second alternative design for the bridge, which is:

• I-Section Steel girder

Classification of LTB Cases:

• (1) if Lb ≤ Lp No LTB• (2) if Lp < Lb < Lr Inelastic LTB• (3) if Lb > Lr Elastic LTB

Where:

• Lb: laterally unsupported length of the compression flange.• Lp : limit for no LTB.• Lr : limit between elastic and inelastic LTB.

Lateral Torsional Buckling LTB

Moment vs. Lb curve

Design Concept

Mu ≤ øMp (Where ø = 0.9)

øMp = Zx * fy

Zx = øMp / fy ; Zx : is the plastic

section modulus

Moment on the Girder

Section

Frame Ultimate Moment (kips.ft)

Ultimate Moment (kips.ft) Zx Zx

1 11356.2 -14195 2725.5

2 6430.12 -13937 1543.23

-3344.

3 8303.63 -9972.3 1992.87

-2393.

4 7816.53 -11038 1875.97

5 7816.53 -11038 1875.97

-2649.

6 8303.63 -9972.3 1992.87

-2393.

7 6430.12 -13937 1543.23

-3344.

8 11356.2 -14195 2725.5

Girder Front View

Section

Selection of the section

Zx= 3406.9 in3

Mu= 14195kips.ft

SAP2000

Ultimate Moment

Frame Ultimate Moment (kips-ft)

Ultimate Moment (kips-ft)

1 6272.05 8525.27 1505.29 2046.072 2734.62 6238.21 656.309 1497.173 3536.51 8382.43 848.763 2011.784 3325.38 8382.43 798.092 2011.785 3325.38 6238.21 798.092 1497.176 3536.51 8525.27 848.763 2046.077 2734.62 8525.27 656.309 2046.078 6272.05 8525.27 1505.29 2046.07

Selection of the section

Zx= 2046.07 in3

Mu= 8525.27 kips.ftSection :

Laterally unsupported length of the compression flange (Lb)

Number of Segments

Case (1) Lb ≤ Lp No LTB

Lb = 24m

Lateral Bracing

Section Lp (ft) Lp (m) Lr

(ft) Lr (m) Lb (m) Lb/Lp

Segments

W40x503 13.1 3.99390

2 55.3 16.85976 21.6 5.40824

Final Section

Girder Front View

SectionW40x503

Economical Issues Detailed Cost

Cost of the Concrete Bridge Deck:

• The volume of the deck = 840 m x 22m x 0.25m = 4620 m3

• The volume of the parapets = [9.86 KN/m x (840 m x 2)] / 25 KN/m

=662.6 m3

• Cost of (1 m3) of concrete = 1500 AED

• The cost for deck and parapets = 4620 m3 + 662.6 m3 x 1500 AED/

m3 = 4.6 x106AED.

Cost of the Concrete Bridge Girders:

• The cost of the girders =Area x Length of Girder x Cost x Number of

girder

=2.625m2 x840mx1500AED/m3 x8=3.31x106AEDCost of the Steel Bridge Girders:

• Cost of (1 ton) of steel = 8000 AED/ton

• Cost of steel girders = weight of whole girders x cost of (1 ton)

= 734.28 ton x 8000 = 5874240 AED

Cost of the Concrete Bridge Pier-caps:• Area of one pier cap =1000 x 2250 =2.25 x 106 mm2 =2.25 m2 • Volume of one pier cap = 2.25 x 22 = 49.5 m3 • Total cost of pier caps = 49.5 x 1500 x 7 = 519750 AED

Economical Issues AlternativeComparison

Total cost of : (AED)

Concrete bridge superstructure 8,429,750

Steel bridge superstructure 10,993,990

Economical Issues AlternativeComparison

• The initial material cost of reinforced concrete is less than

the equivalent steel required for construction.

• Less long term cost of materials used for repairing or

replacing the defected parts, since concrete does not

require high maintenance and protection coatings,

compared to steel.

In general, concrete bridge has lower environmental effects than a steel bridge :

• less influenced by excessive wearing from the moist surrounding atmosphere, because of its low chemical-active nature with moisture.

• Does not require a lot of protection layers, which contain harmful chemicals and highly toxic materials such as paints and protection coats, which means less consumption of material and less harming of the surrounding environment.

• Steel reinforcing steel bars (rebars) used in the bridge could be utilized, after the end of the serviceability, where it could be cleaned and reused, or recycled.

Concrete Bridge Environmental Issues

Environmental Issues

• On the other hand, the possibility of reusing and recycling the

materials is higher for the steel bridge.

• This means more reducing of the waste and its negative

impact on the environment.

SteelBridge

Contemporary Issues

• One of the most important issues regarding the design of the

bridge is having a positive social impact.

• This is achieved by considering the appropriate bridge design.

• This means fewer blockages of the bridge, more flow-ability,

and more convenience and comfort for the users.

Social Impact

Gant chart

Thank You For Listening …

bridge design using SAP

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