Displacement‐based seismic design of multi‐degree‐of‐freedom bridge structures

TLDR

Displacement‑based design focuses directly on displacement demand and damage, making it attractive for seismic design, and the concept of design‑oriented displacement response spectra is also briefly addressed. The study presents a procedure that extends displacement‑based design to complex multi‑degree‑of‑freedom bridge structures. The method assumes a displaced shape for the bridge and reduces the MDOF system to an equivalent single‑degree‑of‑freedom system. The procedure performs well for symmetrical bridges but shows shortcomings when applied to highly irregular bridges.

Abstract

Abstract The concept of displacement‐based design is attractive for seismic design, primarily because it places the focus of design directly on displacement demand, and hence damage, rather than on force‐reduction or behaviour factors. A procedure is presented which extends the simple concept of displacement‐based design to complex multi‐degree‐of‐freedom (MDOF) bridge structures. The procedure is based on the assumption of a displaced shape for the structure, and the subsequent reduction of the system to an equivalent single‐degree‐of‐freedom (SDOF) system. The process is shown to work well for the design of a symmetrical bridge, while suffering some shortcomings when applied to a highly irregular bridge. The topic of design‐oriented displacement response spectra is also briefly addressed.