Seismic analysis of transmission tower under low to moderate earthquake loading

Abstract

In Malaysia, even though the country can be considered as a low seismic area, the structural safety under seismic load has not been studied. Therefore, seismic vulnerability assessment is needed to be performed, especially for the towers. The objectives of this study are to investigate the capacity of tower members, failure mode, determine seismic capacity, and to derive seismic fragility curve for towers in Malaysia when subjected to far-field earthquake. The numerical models of three different heights towers were established in non-linear FE software, namely SAP2000. Equivalent static and response spectrum analysis, Pushover analysis and time history analysis were performed to determine the capacity of the towers members, capacity and fragility of towers, respectively. Totally, 6 far-field earthquake records, which were scaled from 0.05g up to 0.6g, were used in an incremental dynamic analysis in order to obtain fragility curves. Result from this study revealed that plastic hinge formation occurred near the tower base. Capacity curve was proved that the capacity of the studied tower decreases when the height of tower increases, as the length of tower member increases. The result of fragility curves showed that the most vulnerable tower due to far-field earthquake was tower with tallest (63.33m) height, and the probability of damage has significantly increased for the peak ground acceleration (PGA) larger than 0.2g.