| Abstract: |
The most important property of the base-isolation system is to make thebase more flexible than the elements of the superstructure, and it must still bestiff enough to resist typical pounding forces, wind loadings, and similar low-amplitude horizontal forces. However, the potential consequences ofearthquake-induced poundings on seismically isolated buildings can be muchmore substantial, and, thus, should be assessed.This thesis investigates, through numerical simulation, firstly, the effectof the potential pounding incidences on the building response and a comparisonbetween two fixed base buildings two story and two seismically base isolatedbuildings two story under this phenomenon. A parametric study is conductedon this part to investigate the effect of the important parameters of the adjacentstructures on the pounding response. These parameters are the isolator shearcapacity, the post-pre stiffness ratio, the ratio between the masses of thecolliding structures, separation distance between the colliding structures andthe superstructure and base damping ratios. Also, the study investigates theeffect of the presence of the viscous dampers at the points of the collision onthe reduction of the pounding force. A specialized program has been made inorder to efficiently perform numerical simulation and parametric studies on thecontrol system. The effects of certain parameters have been investigated usingthe developed software such as damper yield force, damper stiffness and post-pre stiffness ratio to find the optimum parameter of the viscous damper.The simulation have revealed that. even if a sufficient gap is provided,with which poundings with the surrounding adjacent buildings .at the base ofthe building could be avoided. this does not ensure that the building will noteventually collide with neighboring buildings due to the deformations of theirsuperstructures. Also, Pounding increases the response of the lighter floors ofthe adjacent base isolated buildings while decreases the response of the heavierfloors, but pounding increases the response of the floors of the adjacent fixedbase buildings. Finally, the presence of viscous dampers at the floor levels atthe points of contact increase the dispersal of energy generated by the collision.
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