Analysis Of The Influence Of Shear Keys On Earthquake Vulnerability Of Highway Simply Supported Girder Bridge

There are many bridges in southwestern China,among which simply supported girder bridges are the most common,and frequent earthquakes in southwestern regions.Accurately assessing the seismic performance of such bridges is of great significance to the design of bridges and the study of seismic strengthening strategies.As one of the important anti-falling beam means,shear key is usually ignored in the seismic calculation,which has a certain impact on the evaluation of the seismic performance of the bridge.The thesis will take the simply supported girder bridge that is common in southwest China as an example to study the impact of shear key and other structural parameters on the seismic vulnerability of the bridge.The thesis mainly concludes the following aspects:1.The research status of seismic vulnerability and shear keys of bridges at home and abroad are introduced in this paper,and the deficiencies of the current research on seismic vulnerability of simply supported girder bridges are analyzed.2.Representative sample bridges from the statistical results of the simply supported girder bridge are selected,and sample bridge finite element models are built based on Open SEES,including the use of contact element method to establish the collision model of the beam and the shear key.According to the existing research results,the damage indexes of bridge pier bending failure and bearing deformation failure are established,including analyzing the impact of bridge pier failure mode and dynamic axial force.Ground motion input samples are selected and processed,then nonlinear time-history analysis method based on incremental dynamic analysis(IDA)is used to analyze the response of the bridge.3.The vulnerable positions of bridge pier are found under the action of longitudinal and transverse earthquake,then the vulnerability curves of the component are obtained by the damage overrun statistical method.On this basis,the influence of ground motion input direction,superstructure forms and pier height on vulnerability curves is analyzed.4.The influence of the shear keys on the vulnerable position of the simply supported girder bridge pier is analyzed.Vulnerability analysis on the simply supported girder bridges with shear keys is conducted.By comparing the vulnerability of the two cases with and without the shear keys,the impact of the shear keys on the bending damage and bearing damage is analyzed,and the effects of the shear keys on the pier bending damage and the bearing displacement damage under different ground motion input directions,different superstructure forms and pier height are compared.A simple analysis of the impact of gap and size of shear keys on seismic response is conducted.