Analysis and Design of Concrete Highway Bridge

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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  
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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.
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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.

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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.

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Structural Safety

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

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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.

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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)

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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

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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.
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• 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)

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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.

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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.
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Comparing Properties
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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

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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.

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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.

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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

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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.
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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.
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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.
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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.

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Types of Shear Reinforcement

• Combinations of stirrups and bent longitudinal
  reinforcement.
• Spirals.

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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.
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Slab Design
Slab sections
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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
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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)
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Slab Flexural Reinforcement
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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
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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 )

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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

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Girder Calculation

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Girder Calculation
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Interior Girder Reinforcement
Skin reinforcement calculation
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Interior Girder Reinforcement
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Interior Girder Reinforcement
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Exterior Girders Calculations
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Exterior Cross Sections
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Exterior Cross Sections
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Girder Shear Calculation
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Girder Shear Calculation
Bar 3 is used for all shear reinforcement
(stirrups) Girder Dimensions and Properties for
Shear
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Shear Result for Interior girder
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Shear Reinforcement Distribution
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Shear Results for Exterior girder
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Shear Reinforcement Distribution
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Pier Caps Design
Pier Cap Bending Moment Diagram Due to Dead load
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Flexure Reinforcement Calculation
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Flexural Reinforcement
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Reinforcement Calculation
Bar 3 is used for all shear reinforcement
(stirrups) Pier Cap Dimensions and Properties
for Shear
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Shear Results for Pier Cap
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Shear Reinforcement Distribution
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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.

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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.

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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.

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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.

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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.

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Thank you

• Any Questions?