Research on Natural Vibration Frequency and Structural Stiffness of Continuous Rigid Frame Bridge with Corrugated Steel Webs

Two comparison models of 3-span single cell box variable cross-section continuous rigid frame bridge with corrugated steel webs and the equivalent ordinary concrete continuous rigid frame bridge were designed and constructed.The natural vibration frequency and structural stiffness of continuous rigid frame bridge with corrugated steel webs were studied by experimental testing and finite element method.The measured and FEM calculated results show that the first-order natural vibration frequencies in all directions of the continuous rigid frame bridge with corrugated steel webs are lower than the ones of concrete continuous rigid frame bridge.Among them,the difference of the first-order natural vibration frequency in vertical direction between the two models is smaller,while the differences of the first-order natural vibration frequency in longitudinal and transverse are significant,which indicates that the overall stiffness in all directions of the continuous rigid frame bridge with corrugated steel webs is less than the one of concrete continuous rigid frame bridge.Compared with rigid frame bridge with ordinary concrete webs,its overall stiffness in longitudinal and transverse directions is declined significantly.The decreasing rate of its overall transverse anti-push stiffness is 1.361times as that of the lateral stiffness of the main girder,while the decreasing rate of its overall longitudinal anti-push stiffness is 4.123times as that of the vertical stiffness of the main girder.It indicates that its overall longitudinal anti-push stiffness is more sensitive to the changes of the main girder's stiffness.