Dynamic response of horizontally curved composite steel I-girder bridges

Abstract

The dynamics behavior of horizontally curved composite steel I-girder bridges is investigated by using three-dimensional finite element models. The analyzed bridge is modeled by using ANSYS 15.0 program with SOILD185 and SHELL181 elements to represent concrete and steel members, respectively. AASHTO HL-93 truck is simulated as 3D mass-spring-damper model consisting of five lumped-masses which connected by rigid beams and supported by spring-damper elements which are used to represent the suspension of vehicle body and tires. Gap and actuator elements are used to represent the separation between the tires and road surface and surface roughness condition, respectively. Four different roughness profiles are generated based on power spectral density (PSD) for very good, good, average, and poor roads. The dynamic analysis is carried out under different cases of vehicular loading positions for bridges with radius of curvature ranged from (35 to 200 m). Seven vehicle speeds are chosen to investigate the effect of this factor on the bridge dynamic response, also the effect of bump height at approach span is studied. The results are presented in terms of Impact Factors (IM). The results show that the IM-radius of curvature relationship is significantly influenced by the position of vehicle on transverse sections of the bridge. For the out-lane loading, the IM values for all girders tend to increase as the radius of curvature decreases. A 45 km/hr vehicle speed provides higher IM value for the good roughness bridge to be at 120 km/hr under poor road surface. The bump heights has a significant effect on IMs at lower speed limit, where the IM value increases with the increasing of bump height.