Structural performance of multi-storey building using flat slab and conventional slab to seismic loads (Case study: Faculty building of Sport Science in Universitas Negeri Malang, Indonesia)

Abstract

Innovations to increase the effective height of storeys in buildings are using a flat slab system. Flat slab system is a slab that is only supported by columns without any supporting beam. By the abstain of beams, designers are able to reduce the storey height and to reduce the structural weight. Other than that, flat slabs offer a more flexible installation of building utilities, simpler reinforcement, and simpler installation of scaffolding and formwork. This study was conducted to analyse the performance of flat slabs when applied to buildings compared with the conventional slabs. The flat slab system is expected to be able to withstand gravity and earthquake loads. The Building of the Faculty of Sport Science, Universitas Negeri Malang, with a total of 7 floors and 1 semi-basement was used as research object. This research was conducted using programme simulation, ETABS and SAP2000. The research was intended to analyse the resulting seismic base shear, the fundamental period, the structural stiffness, the ultimate performance evaluation, and the storey drift if the building designed using flat slab system. Results showed that (1) Building with flat slab system has a lighter weight than the one with conventional slab system. Building weight affects the seismic base shear value of the building. The heavier a building is, the greater the seismic base shear value of a building; (2) The fundamental period analysis resulted the structural vibration time (Tc) in flat slab structure is greater than in the conventional slabs. The heavier the building weight, the structural vibration time (Tc) that occurs will be smaller; (3) The structural stiffness of building using flat slab system is less than in the conventional slabs system; (4) Both of building using flat slab system and conventional slabs meet the requirement of service performance and ultimate performance; and (5) The storey drift in building using flat slab system is larger than in the conventional slabs. This is due to the conventional slab structure has a greater stiffness than flat slab structure.