DUCTILITY OF REINFORCED CONCRETE SUB FRAME FOR INDUSTRIALIZED BUILDING SYSTEM

Abstract

An accurate determination of industrialized building system (IBS) frames ductility under alternating lateral loads is the key issue of this study. The performance features of IBS H frame assembly subjected to cyclic lateral pushover test with six attached IBS components are reported. A test scheme of nonlinear elastic sub-frame system is proposed to build an IBS structural building system. This system complies with the requirements of strength and ductility governed by European Codes 2 and 8. The three models are a conventional reinforced concrete H frame system CRCH (Model 1), IBS with steel conventional links as reinforcements IBSHN (Model 2), and special spiral links concrete IBSHS (Model 3). Each model is scaled to 1:5. All models are laboratory examined under cyclic lateral pushover test to failure, where the IBS connections are considered as hybrid partial rigid linking beams to columns. The beam ends are connected to column boxes via a U shaped steel plate. The experimental results of the IBS specimens are compared with the conventional reinforced concrete connection of similar shapes and size in the form of H sub-frame mechanism tested under the same condition. The models are subjected to cyclic lateral load controlled applied at the beam-column connection. The performance evaluation of IBS connections is made via load displacement hysteresis, ultimate and collapse parameter, ductility index, and surface cracks appearances. The conventional concrete specimen is obviously found to display better strength compared to IBS. Conversely, the ductility of IBS H frame specimen with spiral shear links and conventional closed loop links exhibits superior features compared to the conventional concrete specimen which is beneficial to earthquake engineering. It is demonstrated that the performance of the precast concrete structure is highly dependent on the ductile capacity of connectors to each of the IBS component. This is significant especially at the joints such as the beam-to-column connections. Our systematic methods on ductility characterizations of reinforced concrete beams may contribute toward the development of IBS in resisting earthquakes.