ANALYTICAL PROCEDURES FOR THE SEISMIC DESIGN OF HIGHWAY BRIDGES

Although the application of structural dynamics to the bridge engineering field is somewhat in its infancy, it has become apparent that certain types of bridges may be idealized so as to be more easily analyzed mathematically. Penzien and Imbsen developed the Single Mode Spectral Method (SMSM), presented in the ATC-6 guidelines, in an effort to simplify the task of implementing structural dynamics within the field of bridge engineering. The SMSM is used to calculate the seismic design forces of a bridge that can be characterized as having its major dynamic response in a single mode of vibration. This method, although quite rigorous, reduces a complex dynamics analysis to the performance of just two statics analyses. The first static analysis is conducted to obtain the structure period, the second to apply inertial forces consistent with the displaced shape. The SMSM, as formulated, can be applied to many types of bridges, including bridges with either continuous or discontinuous superstructures. Boundary conditions at the abutments and piers can be modeled to include the effects of the foundation. A bridge engineer can readily apply the SMSM by using hand calculations and conventional static structural analysis procedures. For the more complex bridges in the higher seismic zones, the seismic design guidelines recommend the Multimode Spectral Method (MMSM), which is a response spectrum analysis. The computer program, SEISAB (SEISmic Analysis of Bridges), currently funded by the National Science Foundation, was developed by Imbsen et. al specifically to help bridge designers conduct seismic analyses. The SEISAB program has both SMSM and MMSM capabilities. In addition, elastic time-history analysis capabilities have been recently incorporated into the program, allowing the designer to conduct more detailed analyses or correlation studies in which the structure remains within the elastic range. With a minimum amount of input data, this program can generate a structural model for a dynamic analysis of almost every type of deck-girder bridge. (Author)

• Supplemental Notes:
  • Seismic Research for Highway Bridges (US-Japan Program) is a collection of Papers Reprinted Directly from the United States-Japan Cooperative Program on Natural Resources (UJNR) Panel on Wind and Seismic Effects; and the Proceedings of the US-Japan Seminars on Repair and Retrofit of Structures, 1979 to 1984.
• Corporate Authors:

  Pittsburgh University, Pittsburgh

  Department of Civil Engineering
  Pittsburgh, PA  United States  15261

  National Science Foundation

  1800 G Street, NW
  Washington, DC  United States  20550
• Authors:
  • Imbsen, R A
  • Penzien, J
• Publication Date: 1984-6

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 39-69
• Serial:
  • Publication of: Pittsburgh University, Pittsburgh
  • Publisher: Pittsburgh University, Pittsburgh

Subject/Index Terms

• TRT Terms: Bridge design; Bridges; Computer aided design; Computer programs; Dynamic tests; Seismicity; Structural design
• Uncontrolled Terms: Dynamic analysis
• Old TRIS Terms: Seismic properties
• Subject Areas: Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 00394000
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 31 1985 12:00AM