Lecture 1

Bridge Engineering(SE-507)

Department of Civil Engineering

University of Engineering and Technology

Lahore, Pakistan

Lecture 1Dr. AzharSpring 2012

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Introduction-1InstructorDr. M. Azhar Saleem ([email protected])

Lectures Two meeting per week. A field visit to bridge under construction (TBD)

Home Works Home works are due at the beginning of the lecture for which they are assigned

Design Project Not this time.

Examination Two quizzes, Final Exam

Marks Theory = 100, Sessional = 60, Viva Voce = 40

Sessionals Quizzes, Home works, class attendance/participation

Honor Code All homework assignments should be individual work. Consultation with classmates is acceptable as long as it is limited to a discussion of solution techniques.

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Introduction-2Outline of Course

◦ Introduction— Bridge Types◦ Limit states, AASHTO LRFD and loads◦ Moving loads effects◦ Deck analysis and design◦ CIP Reinforced concrete bridges: slab and girder◦ Review of Prestress Concrete◦ Prestressed girder bridges◦ Substructures◦ Bridge load rating

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Introduction-3References Barker M. and Puckett J., Design of Highway Bridges, An LRFD

Approach, 2nd Ed, Wiley & Sons, 2007. AASHTO LRFD Bridge Design Specification, 5th Edition, 2010. The Manual for Bridge Evaluation, AASHTO, January 2009. Tonias D. and Zhao J., Bridge Engineering, 2nd Edition, Mc Graw-Hill,

2007. Leonardo Fernández Troyano, Bridge Engineering: a global

perspective, Thomas Telford, Ltd, 2003. Menn, Christian, Prestress Concrete Bridges, Birkhäuser Verlag, 1990. Nigel R. Hewson, Prestressed Concrete Bridges: Design and

Construction, Thomas Telford, Ltd, 2003. Schlaich J. and Scheef H., Concrete Box Girder Bridges, IABSE, 1982. Publications by FHWA, www.fhwa.org Publications by AASHTO, lrfd.aashtoware.org Publications by the National Steel Bridge Alliance, www.steelbridge.org

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Bridges…Definition Bridges are structures that connect and/or cross

two points separated by a road, river or valley.

In social terms they connect communities, nations, races, etc. and are sign of friendship and peace.

In structural terms, bridges are fascinating structures, a source of challenge to engineers and builders.

In many respects, bridge engineers can express their talent through these art forms and sculptures.

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Bridges…Design Bridges are essential elements of a transportation

network since they control the capacity of the system, and as such they should be carefully planned and engineered.

Unlike other structural systems, bridge design depends on how the different bridge components (deck, girders, etc) are put together or built. In some cases, loads generated during bridge construction control the member sizes. Hence, special attention shall be given on how a bridge is built and shall be clearly expressed or described in contractual documents.

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Transportation Project

Planning

Design

Financing

Procurement

Construction

Maintenance

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Design Process-1

Phase 1: Owner’s Requirements

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Design Criteria

Aesthetics

Functional Budget

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Design Process-2

Phase 2: Design Development

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Preliminary Designs

Development of Alternatives

Selection of Recommended Alternative

Adequate

Cost Effective

Constructible and Maintainble

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Design Process-3

Phase 3: Contract Plans

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Structural Analysis

Structural Design

Plan Production

Specifications and Bid Documents

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Construction Process Construction Engineering

◦ Shop drawings production◦ Construction analysis◦ Falsework design

Construction◦ Crew efficiency◦ Geometry control◦ Storage◦ Equipment staging◦ Temporary bracing◦ Maintenance of Traffic (MOT)◦ Erection sequence◦ Casting

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Types of BridgesSlab-on-stringer (95% of all types)Steel and Concrete Box GirdersSteel and Concrete ArchTrussesMoveable (Lift, bascule and swing

etc.)Suspension

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Types of Bridges

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Slab on Stringer

Box Girder

Arch Truss

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Types of Bridges

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Moveable Bridge

Bascule Lift

Swing

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Types of Bridges

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Suspension Bridge

Golden Gate Bridge

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Span Rang

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Bridge Selection

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Bridge Components

The stone clapper Darth River (Dartmoor) bridge, built in 111 BC by Celtic tribes of Scotland is shown above. It has the same fundamental

elements of a modern highway bridge: a super-structure and a substructure. The stones are quality grade granite.

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Bridge Components Julius Caesar’s

temporary bridge across the Rhine in 56 BC, was built in 3 days, and then dismantled in one day after a successful campaign in Germany.

(“The Conquest of Gaul”, by J. Caesar, 50 BC).

Note the basic elements still present in today’s bridges.

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Bridge Components

The Roman aqueduct/bridge Pont du Gard in France is over 19 centuries old

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Bridge Components

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Bridge Components

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Bridge Components

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End Bent

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Bridge Components

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Typical Components of Box Girder Bridge

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Bridge Components

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Typical Components of Composite I-girder Bridge

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Bridge Components

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A modern slab-on-stringer highway bridge, with steel stringers and lateral bracing

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Bridge Components

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Welded curved steel stringers.

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Bridge Components

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Elements of Substructure

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American Association of State Highway and Transportation Officials (AASHTO)

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AASHTO is a nonprofit, nonpartisan association representing highway and transportation departments in the 50 states, the District of Columbia, and Puerto Rico. It represents all five transportation modes: air, highway, public transportation, rail, and water. Its primary goal is to foster the development, operation, and maintenance of an integrated national transportation system

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American Association of State Highway and Transportation Officials (AASHTO)

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AASHTO LRFD Bridge Design Specifications

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The provisions of these specifications are intended for the design, evaluation, and rehabilitation of both fixed and movable highway bridge.

Horizontally curved concrete girders are not fully covered and were not part of calibration data.

These specifications are not intended to supplant proper training or exercise of judgment by designer, and state only minimum requirements necessary to provide for public safety.

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AASHTO LRFD Bridge Design Specifications

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Bridge: Any structure having an opening not less than 20 ft. that forms part of a highway or that is located over or under a highway

Design Life: Period of time on which the statistical derivation of transient load is based: 75 years for these specification.

Ductility: Property of a component or connection that allows inelastic response.

Extreme Event Limit States: Limit states relating to events such as earthquakes, ice load, and vehicle and vessel collision, with return periods in excess of the design life of the bridge

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AASHTO LRFD Bridge Design Specifications

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Factored Load: The nominal loads multiplied by the appropriate load factors specified for the load combination under consideration.

Factored Resistance: The nominal resistance multiplied by the resistance factor.

Limit State: A condition beyond which the bridge or component ceases to satisfy the provisions for which it was designed.

Load and Resistance Factor Design (LRFD): A reliability-based design methodology in which force effects caused by factored loads are not permitted to exceed the factored resistance of components

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AASHTO LRFD Bridge Design Specifications

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Load Factor: A statistically-based multiplied applied to force effects accounting primarily for variability of loads, the lack of accuracy in analysis, and probability of simultaneous occurrence of different loads, but also related statics of the resistance through the calibration process.

Nominal Resistance: Resistance of a component or connection to force effects, as indicated by the dimensions specified in the contract documents and by permissible stress, deformations, or specified strength of materials.

Resistance Factor: A statistically-based multiplier applied to nominal resistance accounting primarily for variability of material properties, structural dimensions and workmanship, and uncertainty in the prediction of resistance, but also related to statistics of the loads through the calibration process.

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AASHTO LRFD Bridge Design Specifications

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Regular Service: Condition excluding the presence of special permit vehicles, wind exceeding 55 mph, and extreme events, including scour.

Service Life: The period of time that the bridge is expected to be in operation.

Service Limit States: Limit states relating to stress, deformation and cracking under regular operating conditions.

Strength Limit States: Limit states relating to strength and stability during the design life.

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Concluded