H=Hyatt Regency Dallas; U=Union Station
New AASHTO Performance-Based Seismic Design Guidelines
Sunday, October 23, 2022 10:30 AM - 12:30 PM, H-Reunion B
The objective of the session is to provide an overview of the newly adopted AASHTO Performance-Based Seismic Design guidelines for bridges. Bridge designers should attend this session, and learning outcomes include: the relationship of these guidelines with other AASHTO specifications, why they were created, examples of application, and potential knowledge gaps that ACI members may be able to help fill. This session is jointly sponsored by the Transportation Research Board Standing Committee on Seismic Design and Performance of Bridges.
(1) Describe the format of the new AASHTO Performance-Based Seismic Design guidelines;
(2) Discuss the relationship between the existing AASHTO seismic specifications and the new guidelines;
(3) Describe a newly added method of seismic analysis of inelastic structures that is permitted in the new guidelines;
(4) Explain the impact structural damping models have on the inelastic displacement demand in bridge structures.
This session has been AIA/ICC approved for 2 CEU/PDH credits.
Overview of the New AASHTO Performance-Based Seismic Design Guidelines
Presented By: Lee Marsh
Affiliation: WSP USA Inc
Description: The American Association of Highway and Transportation Officials (AASHTO) has recently adopted a new guideline document for bridge owners to use for performance-based seismic design (PBSD) of bridges. These guidelines are an initial implementation at a national level of PBSD for bridges and give designers and owners a methodology for targeting and designing a bridge to meet an appropriate level of performance. This presentation will provide a concise high-level overview of the new guidelines with the goal of increasing awareness of the document and understanding of its relationship with other AASHTO bridge design documents.
New AASHTO PDSD Guidelines - SDOF Column Investigation and Results
Presented By: Chad Goodnight
Affiliation: HDR, Inc
Description: To study the impact of the new PBSD guidelines on a national level, 13 different cities were selected from across the United States. These cities are located both in high-seismic zones and lower zones. Both a 100-year and 975-year return period design were assessed for each location, and a range of column longitudinal steel content and aspect ratios were considered. Two different methodologies for estimating inelastic displacement from elastic response spectrum analyses were used. This presentation will present the results of this study and will bring to light an important finding relative to the way AASHTO currently estimates structure displacement using elastic analyses.
Application of the New AASHTO PBSD Guidelines - Design Examples
Presented By: Stuart Bennion
Affiliation: WSP USA
Description: The application of performance-based seismic design (PBSD) can be more challenging than traditional seismic design, as engineer’s target specific enhances seismic performance. This presentation will outline the PBSD steps that an engineer would generally progress through for a specific project. The design examples will cover two separate interior column configurations, one with concentric interlocking spirals in a rectangular column and one with a traditional circular column. The goal is to understand the process and how engineers have control of the design to meet performance expectations, including changes in direction based on preliminary investigations and the interaction of the various project goals.
Performance-Based Seismic Design of Bridges – Canadian Perspective
Presented By: Saqib Khan
Affiliation: Spannovation Consulting Limited
Description: This presentation will compare the AASHTO seismic provisions to the Canadian Highway Bridge Design Code provisions. As in the U.S., guidelines have been developed in Canada (British Columbia) and these aid designers in applying the code provisions to carry out performance-based seismic design of bridges. The intent of the guidelines is to achieve specific levels of performance using less prescriptive provisions and more direct behaviorally based analysis and design methods. The guidelines, like the new AASHTO PBSD guidelines seek to better inform designers, owners, and other stakeholders of the expected seismic performance of bridges.