Investigation of Natural Frequency for Continuous Steel Bridges with Variable Cross-sections by using Finite Element Method

Abstract

This paper mainly focuses on the natural frequencies of steel I-girder continuous-span bridges with straight haunched sections. The finite element analysis is performed to model dynamic behaviour of bridges by using CSIBridge package. Continuous-span bridges (two to six) with straight haunched section are considered. All the dimensions used for generating bridge models are designed according to AASHTO LRFD Standards. Effect of various parameters such as span length, the depth ratios between haunched cross-section to mid-span cross-section (r), the length ratio between haunched section to span (α), span configuration and steel girder arrangement on natural frequencies are investigated by numerically generating one hundred fifty three bridge models. “r” and “α” values are set to be 0.5 - 2.0 and 0.1 - 0.5. The analysis results are given and discussed for the natural frequency of continuous-span composite steel bridges with straight haunched section.