Experimental assessment of the in-plane lateral drift capacity of precast concrete building cores

Precast concrete construction has become an increasingly popular construction technique in recent years and in many Australian capital cities, e.g. Melbourne, precast concrete walls and building cores have replaced traditional cast in-situ reinforced concrete (RC) walls as the dominant form of construction in low and mid-rise buildings. Precast construction offers time and cost savings to the contractor but may inadvertently reduce the lateral displacement capacity of the core during an earthquake due to unexpected connection failures resulting from the exclusion of any capacity design principles in Australian design standards and codes. This study was initiated to experimentally assess the lateral in-plane cyclic displacement capacity of precast concrete building cores up to the point of axial load failure (i.e. complete structural collapse). The experimental program consisted of three test specimens: one traditional cast in-situ RC core and two equivalent RC cores constructed using jointed precast construction. The first precast core was detailed using normal ductility (i.e. N grade) reinforcing bars whereas the second precast core detailed using low ductility (i.e. L grade) reinforcing mesh. The test results showed that depending on the failure mechanism developed, the displacement capacity of precast building cores can be more than a corresponding cast in-situ core. The testing also highlighted that smart detailing approaches could allow precast walls constructed with low ductility reinforcement to develop similar levels of in-plane lateral displacement to that of precast walls detailed with traditional normal ductility rebar.