Earthquake Analysis Of The Long-span Continuous Steel Arch Bridge Under Multiple Support Excitation

The seismic checking computations for general long-span bridges in china are on thepremise of uniform excitation. In fact, the seismic excitation of long-span bridge roled oneach supporting point is different, because For long-span bridges, the seismic traveling waveeffect, partial correlative effect and the site condition should not be neglected in the process ofseismic wave propagation. The multiple support excitation is the most appropriate method forexcitation input in seismic response analysis.I would like to simulate the earthquake ground motion input which considered thenon-stationary frequency using Du xiuli-Chen houqun spectral based on the theory of randomvibration, the input described the partial coherence between different supports usingMATLAB by the Hao function. This paper calculate the seismic response of the bridge withtravelling wave effect and partial coherence, campared with the results under the coincidentearthquake excitation, and study the influence of travelling wave effect and partial coherenceto the seismic response of a large-span steel arch bridge in lanzhou. The model adopted byMidas/civil.From the comparative analysis of the results in this paper show that the arch rib of thisbridge is weak in lateral rigidity, so the arch ribs are more easily to buckling in lateral. Theresponse of the long-spon steel arch bridge with the travelling wave effect is very differentwith the results. With the increasing of the wave velocity, most parts of the responses with thetravelling wave effect is gradually decreases in nonlinear proportional, and small parts aredecreased first and then increased. The common trends are the higher the wave velocity are,more closer the responses under the coincident earthquake is than the response with thetravelling wave effect. When the wave velocity is very slow, the seismic response of thebridge with travelling wave effect will have a big increase. The seismic response of thelong-span arch bridge with partial coherence is universally much more than that of coincidentearthquake excitation. Under the multiple support excitation, the responsal grows rate of theplace where in the long-span arch far from the ground motion input place with the travellingwave effect and the partial coherence effect is slow than that of the place closer from theground motion input place. From what has been discussed above, The multiple supportexcitation must be considered in the seismic design of the long-span continuous steel archbridge.