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Analysis and Design of Concrete Highway Bridge

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Title: Analysis and Design of Concrete Highway Bridge


1
United Arab Emirates UniversityCollege of
Engineering Graduation Project II
Analysis and Design of Concrete Highway Bridge
Done By Abeer Abdullah 970722811 Amal
Al-Amiri 199903930 Ramla Kalantar
199904023 Advisor Dr. Bilal El-Ariss First
Semester 2004/2005  
2
Objectives

The Objective of the project is to Learn
structural analysis and design of concrete
highway bridges. Acquire the knowledge and
experience of applying the needed codes,
specifications and soft ware.
3
Project discretion
  • Abu Dhabi Municipality commissioned proposals for
    an Overpass Bridge over Abu Dhabi/Dubai highway
    at Al-Bahia residential area.
  • The bridge is 95 m long
  • (311.7 ft).
  • The analysis and design of this bridge was done
    for the superstructure elements.

4
Design methods
  • There are two methods used in structural design
  • In 1900s, the method used in design was called
    the working-stress design (WSD) method. In this
    method service loads were used.
  • Since 1963, the ultimate-strength design method
    was rapidly used. In this method the service dead
    and live loads are multiplied by some load
    factors.
  • The method used in our project is the
    ultimate-strength design method.

5
Structural Safety
  • In Ultimate-strength design method there are two
    approaches by which the structural safety can be
    obtained
  • Load Factors
  • Strength Reduction Factors

6
Structural Safety
  • Load Factors
  • The service loads are multiplied by some load
    factors that are larger than one.
  • Strength Reduction FactorsThe material strength
    are multiplied by a reduction factor less than
    one.

7
Structural Safety
  • Strength Reduction FactorsThe Code provides F
    values for several situations
  • Flexure. F0.9
  • Shear... F0.85
  • Axial compression with Sprials F0.75
  • Ties... F 0.7
  • Bearing on concrete. ..F0.7
  • (AASHTO 8.16.1.2.2)

8
Design Specification
  • AASHTO
  • AASHTO stands for American Association of
    State Highway and Transportation Officials. we
    used the following sections of AASHTO
    specifications
  • Section 3 Loads
  • Section 8 Reinforced Concrete
  • ACI Code
  • ACI stands for American Concrete Institute.
    ACI was founded in 1904

9
Material Used
Reinforced Concrete is a composite material of
steel bars embedded in a hardened concrete. It is
strong durable material that can formed into many
varied shapes and sizes.
10
  • 1. Concrete
  • Cement
  • OPC is the most common type in use.
  • The main chemical compounds in cement are
    calcium silicate and aluminates. 
  • Water
  • when water is added to cement to form cement
    past chemical reaction occur and the mix
    becomes stiffer with time
  • (water cement ratio is an important factor
    affecting concrete strength)

11
Concrete
  • Aggregates
  • The bulk of concrete is aggregate in the form of
    sand and gravel which bounded together by cement.
  • a. Coarse aggregate gravel or crushed rock 5mm
    or larger in size.
  • b. Fine aggregate Sand less than 5 mm in size.
  • Admixtures
  • as setting accelerators or retarders, etc.

12
2. Steel Bars

Reinforcing bars can be plan or deformed, the
bar sizes used in U.S customary units ranges
from 3 thought 18. While in SI units the bar
are numbered 10, 13, 16, 22 and 43. these numbers
represents the bar diameters approximately.
In design we will use 420 MPa, the corresponding
grade in U.S customary unit is 60,000 psi.
13
Comparing Properties
14
Advantages of reinforced concrete
  • Has a high compressive strength.
  • Resists fire actions.
  • Low maintenance material, has a very
    long service life.
  • An economical material and has an
    ability to be cast into a variety of shapes

15
Disadvantages of reinforced concrete
  • Has very low tensile strength.
  • Has a low strength per unit of weight of concrete
    which leads to heavy members.
  • The properties of concrete vary due to its
    proportioning and mixing.

16

Types of needed reinforcement
  • 1.Reinforcement Requirements due to flexure
  • The main reinforcing ,it may not be spaced
    farther on center than 3 times the slab
    thickness, or 18 in.
  • One-fourth the positive moment reinforcement
    in continuous members shall extend along the same
    face of the members into the support in beams, at
    least 6 inches.

17
Types of needed reinforcement
  • Development length (ld)
  • The reinforcement bars must be extended some
    distance back into the support and out into the
    beam to anchor them or develop their strength.
  • The basic development length shall be
  • No. 11 bars and smaller
  • But not less than

18
Types of needed reinforcement

2.Parallel reinforcements
In slabs, A percentage of the main positive
moment reinforcement shall be distributed in the
parallel direction of the traffic
Spacing limits for reinforcement For
cast-in-place concrete the clear distance between
parallel bars in a layer shall not be less. 1.5
bar diameter, 1.5 times the maximum size of the
coarse aggregate, 1.5 inches.
19
Types of needed reinforcement
3.Shrinkage Temperature Reinforcement The total
area of reinforcement provided shall be at least
1/8 square inch per foot in each direction.
4. Skin Reinforcement skin reinforcement will be
uniformly distributed along both side faces of
the member for a distance d/2 nearest the
flexural tension reinforcement. The area of skin
reinforcement Ask per foot of height on each side
face shall be. The maximum spacing of skin
reinforcement shall not exceed d/6 and 12 inches.
20
Types of needed reinforcement
5.Shear Reinforcement If the diagonal tension
exceeds the limited tensile strength of the
concrete then shear reinforcement must be
provided.
21
Types of Shear Reinforcement
  • Stirrups perpendicular to the axis of
    the member.
  • Welded wire fabric with wire located
    perpendicular to the axis of the member.

22
Types of Shear Reinforcement
  • Combinations of stirrups and bent longitudinal
    reinforcement.
  • Spirals.

23
Slab Design
Slab is assumed to e a rectangular beam with a
large ratio of width to depth. A 12-in wide piece
of such a slab is designed as a rectangular beam.
24
Slab Design
Slab sections
25
Slab Design Steps
I ft strip of the slab will be designed and
considers as a continues beam.
  • Live load Moment

(AASHTO 3.24.3.1)
  • Dead load Moment

Mu 1.4 MD 1.7ML
26
Slab Design Calculation
h10 , fc4000psi , fy60,000psi
spans Section (b-b) d 10-1-1/4 8.75
(in) MD 1.1 k.ft ML 4.94 k.ft Mu 1.4 MD
1.7ML 9.938 k.ft
144.2psi (Use table A.14) ? 0.0033 As ?bd
0.3564 in2 Use Bar 4 _at_ 6.5 in (As0.36 in2)
27
Slab Flexural Reinforcement
28
Elevation view
Cover Top reinforcement.2 in. Bottom
reinforcement1 in.
Development length For No. 4 bars 1 ft For
No. 5 bars 1.25 ft
29
Girder Design Steps
  • Minimum depth for T-Girders (0.065S) (AASHTO
    table 8.9.2)
  • Compute Z larger of 0.9d or d-(hf/2)
  • Steel Area
  • Checking minimum reinforcement
  • (larger of )

30
Girder Calculation
  • h 6.93 ft 83.16 in
  • d 83.16-2-0.5-1.693/2 79.81 in 6.65 ft
  • b d/2 39.91 in
  • hf 10 in

31
Girder Calculation

32
Girder Calculation
33
Interior Girder Reinforcement
Skin reinforcement calculation
34
Interior Girder Reinforcement
35
Interior Girder Reinforcement
36
Exterior Girders Calculations
37
Exterior Cross Sections
38
Exterior Cross Sections
39
Girder Shear Calculation
40
Girder Shear Calculation
Bar 3 is used for all shear reinforcement
(stirrups) Girder Dimensions and Properties for
Shear
41
Shear Result for Interior girder
42
Shear Reinforcement Distribution
43
Shear Results for Exterior girder
44
Shear Reinforcement Distribution
45
Pier Caps Design
Pier Cap Bending Moment Diagram Due to Dead load
46
Flexure Reinforcement Calculation
47
Flexural Reinforcement
48
Reinforcement Calculation
Bar 3 is used for all shear reinforcement
(stirrups) Pier Cap Dimensions and Properties
for Shear
49
Shear Results for Pier Cap
50
Shear Reinforcement Distribution
51
Social Impact
  • The Proposal overpass bridge over the Abu Dhabi/
    Dubai Highway at Al Bahiah area will ease the
    movement to and from Al Bahiah residential area
    toward Dubai and Abu Dhabi.
  • Al Bahiah residential will reduce their trip time
    to and from it.

52
Environmental Impacts
  • Advantage
  • 1.Cement is composed of 75 limestone.
  • 2.extracting the raw materials for concrete has a
    lower impact than that of other construction
    materials.
  • 3.Almost all concrete contains fly ash, a
    byproduct of coal-burning electric
    plants.
  • 4.Old concrete that has reached the end of its
    service life can be recycled and reused.

53
Environmental Impacts
  • Disadvantage
  • One tone of cement
  • Requires about 2 tones of raw material
    (limestone)
  • Consumes about 4 GJ of energy in electricity,
    process heat, and transport.
  • Produces approximately one tone of CO2.

54
Economical Impacts
  • Concrete is a durable material that actually
    gains strength over time and conserves resources
    by reducing maintenance and the need for
    reconstruction.
  • Steel and Concrete are widely available in the
    UAE.
  • By reducing the trip time that will economize the
    fuel consumption.
  • Both Steel and Concrete can be recycled and used
    in other applications.

55
Conclusion and Recommendation
  • Through out working on this project we gain
    skills, knowledge and some experience in bridge
    analysis and designing by following the
  • AASHTO and the ACI code.
  • It is recommended to have an original copy of
    AASHTO specifications rather than the not clear
    photocopies we had.

56
Thank you
  • Any Questions?
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