Experimental investigations on semi-continuous encased composite joints

peer reviewedThe benefits brought to composite construction by the use of semi-continuous joints are well recognised and confirmed by the significant amount of research which has been performed in this area. It has been analytically proven that at serviceability limit state (SLS) the performance of composite beams benefits from the use of semi-continuous composite joints [1]. At ultimate limit state (ULS) it is of common knowledge that the use of semi-continuous composite joints is only judicious in combination with the plastic hinge theory, which requires the verification of the rotation capacity of the joint. Despite all the effort done in this area, a concise and well-defined method to determine the rotation capacity of composite joints is lacking. Hence, a research programme with a large experimental part has been designed to investigate the behaviour of the connection between a column and a composite slim-floor beam subjected to a negative bending moment. It is the first time that the rotation capacity of an encased composite joint is analysed. The experimental campaign, presented in here, aims at determining the influence of each joint component on the rotation capacity of composite joints. Three test series have been performed; on boltless beam-to-column connections using variable longitudinal reinforcement ratio and bar diameter of the slab, on a bare bolted end-plate steel connection without reinforced concrete slab and finally on the encased composite joint with the complete bolted end-plate connection. This paper presents a detailed description of the tested specimen, shows the main results of the experimental investigations and gives an outlook on future work regarding this research project. The final goal of the research project is to develop a comprehensive methodology to predict the rotation capacity for traditional and slim-floor type of composite beams