Dynamic Performance Assessment of a Novel Hybrid Bridge System with Spread Steel Box Girders

Abstract

The dynamic performance of a new bridge system utilizing hybrid spread steel box girders, in which the steel box girders are spaced apart instead of conventional multicell box girders, was evaluated based on field tests and numerical analyses. In the live-load-testing program, the novel bridge superstructure was instrumented with a photogrammetric photoelectric transducer to measure the deflection responses of the spread steel box girders at midspan. The test was conducted using standard 38-t trucks under both quasi-static and dynamic conditions, in which the vehicle speed and transverse position were varied. Results obtained from the experimental tests, as well as from the developed three-dimensional finite-element models of the bridge superstructure, were examined to evaluate the dynamic impact factors. The maximum impact factor of the system under moving vehicles satisfies the Chinese and US bridge design codes, indicating that the novel system achieved the desired performance for in-service loading.