Research On Seismic Vulnerability Of Irregular Continuous Beam Bridges Under Near-field Multi-dimensional Ground Motion

With the development of China’s transportation industry,there are more and more continuous beam bridges located in mountainous areas and complex terrains,and the structure of such continuous beam bridges is irregular.At the same time,China is also a country with frequent earthquakes.Irregularities in the structure of continuous beam bridges cause such bridges to generate dynamic responses different from regular continuous beam bridges under earthquakes and are prone to damage.Therefore,it is necessary to analyze the seismic vulnerability of irregular continuous beam bridges.In this paper,three typical irregular high-low pier continuous beam bridges and three typical irregular curved continuous beam bridges are established based on the Open Sees finite element platform.The frequency domain method in elastic half-space theory is used to obtain ground motion rotation through three-way translational ground motion components.In this paper,the incremental dynamic analysis of near-field and multi-dimensional ground motions is performed on the example bridge,and the probabilistic seismic demand analysis method is used to draw the seismic vulnerability curves of six typical irregular bridge key components.The main research contents are as follows:(1)Select appropriate near-field seismic waves from the PEER strong earthquake record database.Each group of ground motions contains ground motion data in three translational directions.Based on the frequency domain method in the elastic half-space theory,the rotational component of the ground motion is obtained,and the seismic response of the structure under two operating conditions is studied based on the inclusion and non-existence of the rotational component.(2)Explain in detail the method and process of bridge seismic vulnerability research based on incremental dynamic analysis,determine the damage index of key components of irregular continuous beam bridges,and determine the use of probabilistic seismic demand analysis methods to draw six kinds of conditions under two conditions Seismic vulnerability curves of key components of a typical irregular continuous beam bridge.(3)Based on Open Sees software,establish three typical six-span high-low-pier continuous beam bridge finite element models and two different curvatures that can take into account the pile-soil effect,component nonlinearity,and abutment effects.A six-span single-curved continuous beam bridge and a six-span S-curve continuous beam bridge finite element model.(4)By comparing the seismic fragility curves of the longitudinal and transverse bridges of the key components of three typical high and low pier continuous beam bridges under two working conditions,the research of the ground motion rotation component on the pier and abutment of the high and low pier continuous beam bridge And the impact of the bearing damage;the differences between the high and low pier continuous beam bridges of different bridge types affected by the ground motion components are analyzed.(5)By comparing the seismic vulnerability curves of the longitudinal and transverse bridges of three typical curved continuous beam bridges of two typical curved continuous beam bridges under two conditions,the research of the ground motion rotation component on the curved continuous beam bridge piers and bridges The influence of the damage of the platform and the support;the characteristics of the influence of the rotation component of the ground motion on the damage of the key components of continuous bridges with different curves.