Abstract
Structural pounding during earthquakes may cause substantial damage to colliding structures. The phenomenon is numerically studied using different models of collisions. The aim of the present paper is to propose an effective formula for the impact damping ratio, as a parameter of the impact force model used to study different problems of structural pounding under seismic excitations. Its accuracy has been verified by four various approaches. Firstly, for the case of collisions between two structural elements, the dissipated energy during impact has been compared to the loss of kinetic energy. In the second stage of verifications, the peak impact forces during single collision have been analyzed. Then, the accuracy of different equations have been verified by comparing the impact force time histories for the situation when a concrete ball is dropped on a rigid concrete surface. Finally, pounding between two structures during earthquakes has been studied. The results of the analysis focused on comparison between dissipated and kinetic energy show relatively low errors between calculated and assumed values of the coefficient of restitution when the proposed equation is used. In addition, the results of the comparison between experimentally and numerically determined peak impact forces during single collision confirm the effectiveness of the approach. The same conclusion has been obtained for the whole impact time history for collision between a ball and a rigid surface. Finally, the results of the comparative analysis, conducted for pounding between two structures during an earthquake, confirm the simulation accuracy when the proposed approach is used. The above conclusions indicate that the proposed formula for impact damping ratio, as a parameter of impact force model for simulation of earthquake-induced structural pounding, is very effective and accurate in numerical simulations in the case of different scenarios.
Highlights
All previously proposed force models, applied to study structural pounding during earthquakes, defineproposed the impact damping basedapplied on the coefficient of restitution
The results of the comparative analysis clearly indicate that using different, previously proposed, impact force models leads to considerably different results for the same Coefficient of restitution (CR) value
The need for an effective formula for the impact damping ratio in order to cover all the responses accurately has been justified in the paper
Summary
It is obviously accepted that insufficient separation distance between buildings, or bridge segments, provides many damages due to collisions during earthquakes, which is called structural pounding [1,2]. Cole et al [34] analyzed damages observed in the February 2011 Christchurch earthquake They found that susceptibility to building collisions during an earthquake can be identified with adequate accuracy by comparing specified configurations with characteristics previously noted by researchers. It is worth mentioning the recent publication by Crozet et al [35] who carried out the shaking table experimental tests which can be utilized as reference tests to be compared with the results of numerical analyses. A number of the above-mentioned analyses considered the numerical models which can accurately simulate impact force in the specific situation taking into account the amount of dissipated energy during collision. The effectiveness of the formula is confirmed by four different approaches
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