Investigation and analysis of the effects of velocity-dependent friction on structures equipped with friction dampers under earthquakes

In this study, structures equipped with friction dampers under the influence of far-field and near-field earthquakes are investigated. How they slide and vibrate, which includes displacement, velocity and acceleration, is calculated by numerical analysis. And the response of the structure under the effect of far-field and near-field earthquakes on the one hand and also considering the simple friction model of Columbus and the more complete model of velocity-dependent friction (Stribeck friction) is compared. Although the possibility of a far-field earthquake is very likely, but the occurrence of large earthquakes near cities that are near faults is undeniable, and these earthquakes have certain specifications that distinguish them from far-field earthquakes. Some of these specifications are such that if neglected, they will lead to underestimation of the seismic force in the design of structures. Examples of these specifications are fling step effect and the presence of velocity pulse in the component perpendicular to the fault that is caused as a result of the phenomenon of forward directivity.Due to the nonlinear behavior of the damping force (FD), programming has been used to perform nonlinear analytical dynamics. Also, behavioral models in Open Sees software are used to investigate the behavior of Stribeck friction for friction damper and to compare its results with the results obtained from accurate analysis. The results show that simplifications of the sliding friction model, on the one hand, and lack of focus on near-field earthquakes, on the other hand, result in underestimation of displacements, especially in member forces. Considering Stribeck friction, error rate is reduced and results are improved.