Highway Bridge Design and Strengthening Using LRFD

Instructor

Bala Sivakumar, P.E., M.ASCE
Mr. Sivakumar is the Chief Engineer for Lichtenstein Consulting Engineers, Paramus, NJ and has directed many of the firm's major bridge design, rehabilitation and evaluation projects in various states. He has over 24 years of diversified bridge engineering experience and has served as the Co-Principal Investigator of NCHRP Project 12-46. Bala was the primary author of the AASHTO Guide Manual for Load and Resistance Factor Rating of Highway Bridges, developed under NCHRP 12-46 to be consistent with the AASHTO LRFD Bridge Design Specifications. He is currently the Principal Investigator of NCHRP Project 12-76 that will develop Protocols for collecting and using traffic data for developing and calibration live load models for LRFD bridge design. He has taught courses on LRFD and LRFR for many professional organizations, industry groups, and several state DOTs. Bala is frequently invited to make technical presentations to the AASHTO Bridge Sub-Committees during their annual meetings and has authored many technical articles on LRFD, LRFR and bridge engineering and serves on several technical committees.

Course Description

AASHTO and FHWA have set a transition date of October 1, 2007 after which all new bridges shall be designed by the LRFD Specifications. Several State DOTs have already implemented the LRFD Specifications and others are currently making their transition to the new specifications. The AASHTO LRFD Bridge Design Specifications introduce a limit states design philosophy, based on structural reliability methods, to achieve a more uniform level of safety (reliability) in new bridge design.The LRFD Specifications is also a state-of-the-art document that advances new developments in structural forms, structural behavior, live load and resistance models, and methods of analysis. The purpose of this seminar is to concentrate on the fundamentals of LRFD for highway bridge design and evaluation. The LRFD approach is broken down into its basic components and a detailed explanation is provided on how and why each component was developed. The course will begin with an overview and introduction to LRFD for new bridge designs, illustrated with two design examples, and build on this knowledge to extend the LRFD philosophy and standards to the evaluation of existing bridges. The course will provide a practical introduction to the many new technologies advanced in the LRFD Specifications, including the limits states design philosophy, the use of notional live load models, and the application of structural reliability methods to achieve a more uniform level of safety in bridges. LRFD live load models, load factors, distribution factors, load combinations, and design provisions for steel and concrete bridges will be reviewed and illustrated with detailed design examples with step-by-step explanations.

Nearly all existing bridges have been designed to other loads and standards than are specified in the LRFD Specifications for new bridges. In 2003, AASHTO published a new Guide Manual for the Load and Resistance Factor Rating (LRFR) of Highway Bridges. The new Manual is consistent with the LRFD Specifications and extends the provisions of the LRFD Specifications to existing bridges. The course will discuss load rating procedures for HL-93, legal loads, and over-weight permit vehicles. Examples with detailed step-by-step explanations will be used to illustrate the LRFR rating procedures.

Seminar Benefits

• Understand the fundamentals of the LRFD philosophy
• Understand the fundamentals of structural reliability and calibration of the LRFD Specifications
• Understand the new technologies introduced in the LRFD Bridge Design Specifications
• Learn about the changes to the load and resistance models and comparison of LFD and LRFD designs
• Learn how to interpret and apply the LRFD Specifications to new bridge design
• Learn through easy-to-follow design examples with detailed explanations
• Get the latest information on LRFD research and software
• Learn the fundamentals of Load and Resistance Factor Rating for highway bridge evaluation
• Learn how to load rate bridges for legal loads and permit loads using LRFR
• Obtain an understanding of how to plan and implement effective structural evaluation, strengthening, and rehabilitation policies and procedures using LRFD for bridges in your region

Who Should Attend

• Experienced Bridge Designers and Evaluators (with or without knowledge of LRFD)
• Junior Engineers/Structural Engineers
• Senior Managers/Project Managers
• Bridge Owners
• Transportation Policy Makers and Decision Makers
• Program Mangers Responsible for Implementing Capital and Maintenance Programs
• Other Bridge Engineering Professionals
• Engineers in Related Fields Interested in Learning about the latest in LRFD for Bridges

Summary Outline

Day One

• Introduction to LRFD and the Limit States Philosophy
• Overview of New Technologies Introduced in the LRFD
• Loads, Load Factors, and Load Combinations
• Reliability Index and Calibration of Load Factors
• LRFD Live Load Models and Distribution of Live Loads
• Limit States for Design of Superstructure and Substructure Components
• Overview of LRFD for Foundation Design
• LRFD Steel Design Provisions:
  • Flexure
  • Shear
• LRFD Fatigue Design Provisions for Steel Bridges
• Constructibility Checks for Steel Bridges
• LRFD Steel Design Example

Day Two

• LRFD Concrete Design Provisions
• Unified Provisions for R/C and P/S Concrete Bridges
• LRFD Flexural Design Provisions
• Shear Design Using the Modified Compression Field Theory
• LRFD Concrete Design Example
• Introduction to the new AASHTO Guide Manual for Load and Resistance Factor Rating of Bridges
• Load Models, Reliability Indices, Limit States and Load Factors for Bridge Evaluation
• Load and Resistance Factor Rating Procedures
• Resistance Modification Factors and Redundancy Factors for Existing Bridges
• LRFR Examples