An Updated Analytical Structural Pounding Force Model Based On Visco-elasticity Of Materials And Application On Pounding TMD

Poundings between adjacent structures induced by horizontal seismic action is a common phenomenon during earthquakes,and poundings may lead to damages even collapse of whole structure.However,the process of components' collision is a course of energy dissipation with momentum decreasing gradually.Therefore,the energy dissipation during pounding process can be applied to structural vibration control to reduce the seismic induced vibrations.In this paper,viscoelastic pounding force analytical method is firstly introduced based on viscoelastic constitutive model.When viscoelastic material applied to collision,high energy absorption effect can be achieved.An offshore jacket-type platform and a 14-stories steel structure are slected to investigate the seismic performance of multiple PTMD device.1)A brief intrution of visco-elasticity of materials is proposed.Based on the summary of existing pounding force analytical models,an updated pounding force analysis method is put forward by introducing visco-elastic constitutive model and contact mechanics method.From separating classic pounding model parameters into geometry parameters and visco-elastic material parameters,traditional Kelvin visco-elastic pounding force model can be expanded to 3 parameters linear solid visco-elastic model.2)Two existing pounding examples,steel-to-steel and concrete-to-concrete collisions,are recalculated using the proposed method and compared with other pounding force models.The result demonstrated that the proposed model accurately simulates both elastic and plastic collision.The parametric study indicates that C1 and E2 can influence the simulation significantly,but nor to E1.A shake table test based on an experimental structure was conducted to verify the effectiveness of PTMD as well as the proposed pounding force model,and the result indicates the new model can also applied to continuous collisions.3)This paper investigates the control performance of pounding tuned mass damper(PTMD)in reducing the dynamic responses of SDOF(Single Degree of Freedom)structure.Taking an offshore jacket-type platform as an example,optimal damping ratio,gap between mass block and viscoelastic material are presented depending on a parametric study.Control efficiency influenced by material properties and contact geometries for PTMD is analyzed here,as well as robustness of the device.The results of numerical simulations indicated that satisfactory vibration mitigation and robustness can be achieved by an optimally designed PTMD.Comparisons between PTMD and traditional TMD demonstrate the advantages of PTMD,not only in vibration suppression and costs but also in effective frequency bandwidth.4)Vibration control performance on MDOF of PTMD with viscoelastic pounding layers is investigated.By using of viscoelastic pounding force analytical method,two types of pounding force models for different contact geometries are developed to illustrate interactions of pounding components in PTMD.Furthermore,a parametric study for a 14-storeys steel structure is presented to investigate the performance of PTMD device in multiple degree of freedom(MDOF)system.The results of numerical simulations demonstrated that properties of viscoelastic material and gaps between mass block and the limiter in PTMD are key factors for vibration control performance.By inputting a series of seismic excitations into MDOF system,comparisons between PTMD and traditional TMD reveals that optimized PTMD has superior performance than the traditional TMD not only in vibration suppression but also in the costs.