Excellent Instructors that have a wealth of knowledge on the subject matter.  Joseph Fazio, Transystems, Langhorne, PA

Seismic design and retrofitting of bridges is progressing from a force-based approach to a new performance-based approach. This change is reflected in the recently published NCHRP 20-7(193) report Recommended LRFD Guidelines for Seismic Design of Highway Bridges being considered for adoption by AASHTO to replace the current Division 1-A.

The seismic hazard has been changed from 10% to 5% probability of exceedence in 50 years increasing the return period from 500 to 1000 years. This increased hazard together with the new Two Point Method for describing the design spectra are improvements in the definition of the seismic hazard throughout the United States. These improvements are particularly important for the eastern portion of the conterminous United States in establishing a more realistic representation of the larger earthquakes that could occur in this region. Additionally, site effects on the ground motions have also been expanded from four to six in the new guidelines to include the current technology in soil response. Site coefficients are now given for the short-period range and the long-period range.

Seismic Design Categories (SDC) is partitioned into four groups to define the design and detailing requirements for the range of seismic hazards throughout the United States.

The new guidelines include a catalog of earthquake resisting systems and components from which to choose from to obtain an optimum overall seismic design for the type of bridge the design has selected for design. Three types of overall seismic design strategy are defined which include:

• Ductile substructure with an essentially superstructure,
• Essentially elastic substructure with a ductile superstructure, and
• Elastic substructure and superstructure with a fusing mechanism at the interface between the substructure and superstructure.

A new FHWA manual entitled Seismic Retrofitting Manual for Highway Structures: Part 1-Bridges 2006 will be referenced in the lectures. This manual is a synthesis of the previous manuals and the recent results from research and lesions learned from post-earthquake investigations.

Seismology, structural dynamics, and some computer applications are reviewed, but the main thrust of the seminar is the AASHTO seismic specifications plus the upcoming changes to be made in the LRFD (Load and Resistance Factor Design) Specifications. Recently funded efforts by FHWA and NCHRP to assist in the implementation of the LRFD seismic design technology has now been completed and will be presented in this seminar. The objectives of these efforts were to recommend a national seismic hazard, expand the limited and no analysis zones, and streamline the Guidelines into a consensus user friendly document. This seminar is tailored to bridge configurations applicable to the entire country including cast-in-place, steel and precast bridges. Additional topics include seismic loading, seismic response analysis, plus design and retrofit concepts.

• Apply the Recommended LRFD Guidelines for Seismic Design of Highway Bridges
• Learn more about the basis for the newly selected design earthquake for a 5% probability of exceedance in 50 years (i.e., 1000 year return period) along with its use for both design and retrofitting
• Understand and apply the principals of performance based seismic design
• Identify seismic vulnerabilities in existing bridges as observed in past earthquakes
• Apply retrofit techniques as described in the recently published FHWA Seismic Retrofit Manual for Highway Structures: Part 1 - Bridges
• Understand basic structural dynamics and the earthquake response of bridges
• Learn more about the available retrofitting hardware available for improving the seismic response of new and existing bridges
• Conduct pushover and rocking analyses
• Learn how to evaluate the seismic retrofit cost and affiliated benefits to other serviceability loadings included in evaluation lifecycle costs
• Develop alternative analytical models to determine the seismic response of a bridge using the available seismic design strategies
• Learn about the computer programs specifically developed and used for both seismic design and retrofitting of bridges
• Receive a demonstration copy of the CSI SAP2000 structural analysis program with the enhancements tailored specifically for the application of the new seismic design guidelines
• Receive brochures from manufacturers producing devices to improve seismic response of bridges
• Receive LRFD Seismic Analysis and Design of Bridges Reference Manual

• Apply analysis techniques to design new bridges and assess existing bridges
• Apply the current seismic design specifications of AASHTO
• Apply the seismic design specifications of proposed new AASHTO LRFD specifications
• Gain knowledge of the basics of retrofit techniques of existing bridges

Achievement of the learning outcomes will be assessed through a series of case studies and problem-solving exercises.

All participants receive the publication LRFD Seismic Analysis and Design Reference Manual and Seismic Retrofitting Manual for Highway Bridge Structures, Part 1.

Structural design engineers who are responsible for designing highway bridges. Note: While this seminar should be of interest to bridge engineers at all levels, it is primarily for experienced designers seeking to learn more or desiring a refresher on the AASHTO seismic design specifications and upcoming changes to be made in the LRFD specifications.

Time:  8:30 a.m. - 4:30 p.m.

Introduction to Seismic Design and Retrofitting of Bridges  

• Past earthquake damage to bridges
• Seismic design and philosophy
• Seismic design and retrofitting strategies

Fundamental Concepts in Structural Dynamics

• Dynamic loading and the d’Alembert Principle
• Single degree-of-freedom systems

Introduction to Seismic Design

• AASHTO Specifications, Div.1-A
• Example problems and solutions
• Seismic base isolation

Seismic Loading

• Seismic design loading

Design Concepts  

• Abutments, columns, footings
• Reinforced concrete columns and piers
• Bearings, restrainers, shear keys
• Example problems and solutions

Seismic Response Analysis

• Practical modeling guidelines
• Equivalent static force methods
• Single mode spectral
• Multi-degree-of-freedom systems
• Example problems and solutions
• Pushover and rocking analysis

LRFD Guidelines for Seismic Design

• Interactive USGS maps
• Seismic design categories SDC A B C D
• Earthquake resistant systems
• Implicit and explicit displacement capacity
• Superstructure and substructure modeling
• Concrete and steel component design

Retrofitting

• Retrofitting concepts
• Example problems and solutions