CAIT project no.: 127 RU6995
Fiscal Year: 2002/2003
Rutgers-CAIT Author(s): Husam Najm, Hani Nassif, Nenad Gucunski, Suhail Albhaisi. Parham Khoshkbari
External Author(s): Anthony Chmiel
Sponsor(s): NJDOT, FHWA
This study evaluates the impact of the newly recommended seismic design guidelines from NCHRP 12-49 on seismic design of bridges in New Jersey. It also provides seismic design criteria and guidelines for integral abutments, retaining walls, embankments, and buried structures. The study provides an overall review of the recommended guidelines and compares them to the current AASHTO LRFD specifications. It provides recommendations on seismic hazard and performance objectives and soil site factors for New Jersey that incorporates design criteria from NCHRP 12-49 guidelines, AASHTO LRFD specifications,
South Carolina seismic design criteria, and NYCDOT seismic design guidelines. The study also includes two design examples based on the NCHRP 12-49 guidelines and current AASHTO LRFD specifications. Research results showed that: (1) the MCE ground motion level adopted by NCHRP 12-49 which has a 2500 years return is acceptable for safety evaluation of ‘critical bridges’ in New Jersey, (2) a reduced (2/3 MCE) ground motion is acceptable for safety evaluation of ‘non-critical’ bridges, (3) soil-site factors have increased dramatically for soft soils subjected to small ground motions which will have an impact on seismic design in Southern Jersey, (4) the USGS National Seismic Hazard Maps adopted by NCHRP 12- 49 for ground motion accelerations may not necessarily reflect the actual geological soil conditions and realistic hazard levels in New Jersey, and (5) NCHRP12-49 SDAP E (pushover analysis) is preferable for the seismic analysis and design of bridges in New Jersey, and (6) NCHRP12-49 SDAP C is a relatively simplified design procedure for many bridges and should be used when applicable. Recommendations from this study include adoption of NCHRP 12-49 subject to above conclusions. However, there is a need to: (1) predict extreme earthquake events for New Jersey and the Northeast United States, (2) prepare Seismic Hazard Maps for bridge design in New Jersey and re-evaluate NCHRP 12-49 soil-site factors proposed for New Jersey, and (3) quantify damage level by using structural capacity and demand.