Seismic performance of low ductile RC frame designed in accordance with Malaysia National Annex to Eurocode 8

Abstract

Eurocode 8, BS EN 1998-1:2004 is specifying Class II ordinary buildings shall be designed to interstory drift limit with displacement reduction factor, v=0.5 at damage limitation. However, Malaysia National Annex, MS EN 1998-1:2017 is specifying a more linear requirement, where no damage limitation limit state check required for Class II ordinary buildings. Historical events and past studies showed that Malaysia is expose to great seismic risk under both long-distance and near fault earthquake. Past researches reported that low ductile RC frame with infilled walls and ground floor soft story has greater tendency to experience brittle failure in vertical elements. This is due to strong column weak beam and excessive story drift. This study investigates seismic performance of residential buildings built with low ductile infilled RC frame with drift uncontrolled in Malaysia. Seismic performance (plastic hinge formation, base shear, displacement, story drift) of structural elements (columns and beams) and non-structural elements (infill wall) were investigated using non-linear static pushover analysis. At performance point, only immediate occupancy, IO plastic hinges founded in column and beams for all buildings cases which implies that seismic performance of buildings are not affected by storey, drift controls and soil types. At performance point, formation of collapse prevention, CP plastic hinges in infill walls are significant in drift uncontrolled building than drift controlled building and on soft ground relative to stiff ground. In short, results indicate that after a design earthquake, vertical and lateral force resisting systems of all buildings studied retain nearly all their pre-earthquake strength. However, infill walls experience extensive damage. According to damage performance evaluation, 4, 7 and 10 story low ductile RC frame with infilled walls and ground floor soft story with drift controlled and drift uncontrolled conditions, Class II ordinary buildings built on stiff soil and soft soil in Malaysia are not achieving intended targeted structural performance level required, life safety under design earthquake.