Multiple Support Seismic Response Analysis Of Large-scale Aqueduct

The seismic input is the hypothesis of structural response.It is assumed in the conventional coherent-vibration input that all of the support points have the same ground movements. As for as the large-span structure is concerned, there is difference in ground movement between different points. Coherent-vibration input can't reflect the earthquake movement change. Therefore, multi-input should be taken into utility.The paper is based upon the seismic response analysis of the Ming-he aqueduct. Using ANSYS soft ware, one-span modal and three-span modal is founded. According to Ansys Parameter Design Language, coherent-vibration input program and multi-support seismic input program is compiled. Contracting the solution of multi-input to three-span modal, coherent-input to three-span modal, coherent-input to one-span modal, the paper show the influence of model and travel-wave effect.As key nodes ,six nodes are choose in both one-span modal and three-span modal respectively at side-bottom-plate, longitudinal beam, brace beam, mid-bottom-plate, mid-wall-plate and side-wall-plat. Comparing response of one-span modal under coherent-vibration input with response of multi-span modal under coherent-vibration input, the conclusion that how the model effect the seismic response is achieved. Comparing response of three-span modal under coherent-vibration input with response of three-span modal under multi-support input, the conclusion that how the travel-wave effect impact the seismic response is achieved.. Analysis results in the conclusion: (1) Among the responses ,x displacement is effected most seriously by model .Under exciting of x director ,Ux in three-span model is bigger than that in one-span model while other response component in three-span model is smaller than that in one-span model. Under exciting of x director, Ux in three-model is smaller than that in one-span model as same as Uy and Uz. More over ,Fy, MX and Mz in three-span model is bigger than those in one-span model .Fx, Fz and Mz in three-modal is smaller than those in one-span model . Three-span model is more coincident with fact than one-span model. Response components in one-span model are lagger than those in three-span model in brief. (2) Taking the travel-wave effect into consideration ,many response components are not influenced by it. However ,some are effected very seriously .For example ,displacement along the exiling direction decreased clearly but displacement vertical to the exiting direction have the trend of increasing. Under exciting of x director ,with the except ofUx and My decreasing greatly, other response components change little. Under exciting of y director ,Uy decrease greatly and Uy increase greatly. Ather response components change little. Coherent-vibration input is the conventional method which should be verified by multi-support seismic input...