| Circum-Pacific seismic belt and Eurasian seismic belt in China are the two most active seismic belts in the world,which have caused great disaster to the production and life ofChinese people.The two methods of displacement-based seismic design and energy dissipation seismic technology have the same starting point,that is,when a large earthquake occurs,it is necessary to reduce the damage to the building structure itself,in addition to protecting the people in the building from harm,thereby reduces the economic losses caused by the earthquake.In this paper,the two methods are studied combined to the displacement-based seismic design of additional viscous dampers.The main contents and conclusions are as follows:(1)A nonlinear hysteretic system used for with nonlinear viscous dampers is proposed.Through the linearization processing of different forms of the additional system,two equivalent models are established.The results of resonance curve show that the equivalent model A has higher accuracy than model B,and model A can be applied to time-procedure analysis without explicit calculation of structure damping ratio;and that model B has a simpler structure while ensuring certain accuracy,and model B can match up well with the existing structural response prediction methods based on seismic response spectrum,so it can be widely used in structural design or structural analysis.On the basis of model B and considering the influence of seismic input,the modifier formula of equivalent damping ratio under seismic action is regressed by application of the concept of optimal damping ratio.An equivalent linearization method for the displacement calculation of nonlinear structural systems under seismic action is established.The time-procedure analysis of 48 different structural parameters combination shows that,The ratio of the prediction results to the time-procedure analysis results under various parameter combinations is close to1.The modified equivalent model can better predict the seismic response of the nonlinear viscous structural system stated in this paper.(2)Based on the equivalent linearization method of above nonlinear viscous dampers,a displacement-based seismic design method used for multi-layer structureswith additional nonlinear viscous dampers is proposed.The stiffness loss and the stiffness of the fastenings of the viscous damper are taken as the design parameters,the additional stiffness provided by the viscous damper is taken into consideration,and the stiffness distribution of the structural system is optimized.The equivalent stiffness of each layer of the structural system with viscous dampers after design is directly proportional to the shear force at the target displacement.The layer shear model was established by using the time-procedure analysis software PC-ANSR.Eight artificial seismic waves were selected to conduct seismic design for 27 kinds of structures with different initial stiffness,yield stiffness ratio and yield displacement angle distribution.The distribution mode of layer shear force adopts Japanese Ai distribution.The results show that the interlayer displacement of the system with viscous dampers is smaller than that of the target layer,and the dispersion degree is good,the preestablished performance target is basically achieved.(3)Because of the largen of shear coefficient of the superstructure caused by the pulse-type ground motion.If the Ai distribution is continued to be used for design of the structure,The maximum interlayer displacement angle of the upper part of the structure will higher than that of the target layer.The maximum layer shear force distribution model based on pulse-type near-field ground motion is used in the design.The displacement-based structural design of SSS type structure is carried out by selecting 4 actual measured pulse-type ground motions and using the time-procedure analysis software PC-ANSR.The final design results can also satisfy the target interlayer displacement angle. |
PDF Full Text Request