A study on the design parameters of the compliant LCD for structural vibration control under near fault earthquakes

Abstract

Earthquake ground motions, recorded in near-fault zones, differ from far-field earthquake excitations. The forward directivity effect often results in high magnitude long period pulse(s) in the velocity time history along with large ground displacement. Again, because of the short travel distance, the ground motion is rich in high frequencies. Consequently, both short period as well as flexible structures have very high damage and collapse potential under near-fault earthquake ground motions. Nowadays, the focus of researchers is seismic protection of structures by use of control devices. Amongst the relatively low-cost but reliable and effective passive control devices, the Liquid Column Damper (LCD) has gained ground but it is only applicable to flexible structures. The Compliant LCD (CLCD) is found suitable for short-period structures as well. In this paper, the performance of the CLCD is investigated for SDOF structural systems subjected to both fault normal and fault parallel earthquake motions, including the fling effect. The sensitivity of the damper performance to the CLCD design parameters is examined in detail. The study indicates that the CLCD is capable of acting as a control device for such earthquake vibrations. The results of the parametric study indicate design trends some of which are different from the existing ones for far-field ground motions.