| The non-regular high pier large span continuous rigid bridge has become the preferred bridge type for complex terrain areas such as southwest mountainous areas due to its economy,strong ability to adapt to the terrain,and large span.Because it is beyond the application range of the code,it brings some difficulties to the designers.Traveling wave effect on the structure or favorable or unfavorable,the influence of numerous factors,has not yet reached a consistent conclusion.Therefore,it is particularly important to carry out corresponding research for non-regular high pier large-span continuous rigid bridges to improve the seismic design theory of special bridges.As a new seismic performance method,the Endurance time method(ETM),with its increasing seismic amplitude with time,can obtain the response of a structure under different earthquake intensities with only a few nonlinear time analyses,which is highly advantageous in the nonlinear dynamic analysis of large complex structures.In this paper,the seismic response and damage development of a seven-span continuous rigid bridge with a pier height of 192 m are analyzed using the seismic time-step method,and the applicability of the method in bridge engineering is verified with the results of IDA analysis.On this basis,the analysis of seismic susceptibility of high pier large span continuous rigid bridge considering traveling wave effect was carried out.The main research contents of this paper are as follows:(1)Endurance time accelerogram(ETA)requires that the acceleration response spectrum is proportional to time t from zero moments to a specific moment t.The nonlinear least squares method solves the optimization equations for unconstrained variables.Three seismic time curves with a duration of 30 s and following the response spectrum of the seismic code of China’s bridges are optimized and synthesized.(2)Based on CSi Bridge software,a three-dimensional spatial finite element model was established,and the three synthetic seismic time curves were input along the longitudinal and transverse bridge directions.At the same time,seven natural ground vibrations were selected for incremental dynamic analysis,and the seismic response of the bridge under different seismic intensities was comparatively studied.The results show that the seismic time duration method can predict the dynamic response of high pier and large-span continuous rigid bridges under different seismic loads efficiently and accurately.The results show that only three-time analyses are required to predict the structural damage process,which can efficiently predict structural failure quickly.(3)The effect of the traveling wave effect on the seismic response of bridges was investigated by applying the seismic time duration method and combining it with the displacement loading(DM)method.The results found that: the traveling wave excitation in different directions has different effects on the same member;the single-limb hollow thin-walled pier with higher stiffness has obvious regularity under the traveling wave effect,while the double-limb solid pier with lower stiffness has regularity under the traveling wave effect related to the response type;the change of excitation direction under the consistent excitation does not affect the structural dynamic response.By converting the seismic holding time t into spectral acceleration,the seismic susceptibility curve of the bridge can be drawn based on the capacity-demand ratio logarithmic regression curve.The results show that the traveling wave effect will reduce the probability of minor and moderate damage to single-limb hollow thin-walled piers,but will increase the probability of damage to the bearings;the seismic susceptibility of the members near the wave source is significantly affected by the traveling wave effect,and is more prone to damage than the members at the distant wave source;the excitation direction should be considered when evaluating the traveling wave effect on the seismic susceptibility of double-limb solid piers. |
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