SEISMIC PROTECTION OF TELECOM AND E-BANKING EQUIPMENT

Abstract

Motivated by the protection of communication facilities and making them available after earthquakes, this study focuses on understanding the equipment behavior, identifying factors worst affecting them and also examining possible ways of protecting them. The dynamic behavior of equipment idealized as rigid blocks subjected to ground excitation is examined. The floor acceleration, the trend they follow in amplification and how the equipments are affected by this amplification are also studied. The equations governing the sliding, rocking response and toppling of the system subjected to horizontal and vertical ground accelerations are derived for each pattern. Displacement model is developed based on coulombs law and impact model is developed by conservation of angular momentum considerations. The behavior each being governed by nonlinear differential equations is solved numerically using Runge Kutta method, based on this mathematical model a program has been developed in Java to take in the floor accelerations as input and give equipment response as output as well as the design of fixity arrangement. It has been identified that the predominant modes of failure are sliding, rocking and toppling. Failure modes considered in this study are essentially dependent on coefficient of friction, aspect ratio and vertical acceleration. Upon sliding, there is concern that the equipment may be damaged either by falling from the bench-top surface or through impact with neighboring equipment or surrounding sidewalls, or may block the primary way to escape. On the other hand rocking and toppling could lead in loss of data, physical damage of circuits and irreparable damage. It is found that restrainers are most effective in preventing overturning, but they tremendously increase the acceleration which may distort the equipment framing, which is not permitted as these equipments are classified as acceleration sensitive. But this study also uncovers that choosing optimum values of initial tension in restrainers can significantly reduce the accelerations coming to the equipment at the same time keeping displacements under acceptable limit.