Experimental validation of the tensile monotonic behaviour of novel dry-connections for precast composite concrete walls

The construction sector is showing renewed interest in prefabrication, particularly in modular construction and building systems based on precast walls. This is mainly due to the current lack of workmanship combined with the costs associated with construction time which make this system a very interesting solution, since it makes construction on-site easier and faster. Therefore, the assembling process of the precast elements must be simple but, at the same time, the connections between the walls must comply with the designed performance of the structure. In this context, an innovative eco-efficient precast structural wall was developed combining ultra-high durability concrete (UHDC) with low-cement lightweight aggregates concrete (LCLWAC). This paper presents a study addressing the development of novel dry-connections, aiming the easy assembling and disassembling of the precast walls referred to. These connections were designed and detailed to avoid on-site concreting, thus significantly reducing workmanship needs. Three new bolted connections were developed for vertical joints between precast walls considering the tolerances required for the assembly process and the stiffness, strength and ductility necessary for the structural performance. To assess the structural behaviour of these connections monotonic tensile tests were performed. The results show that all connections can properly transfer a concentrated tensile load to the concrete wall, with reduced cracking, namely at service conditions. Main conclusions are presented, as well as improvements to be studied next, and adequate production control is recommended, namely at the UHDC-LCLWAC interface, to guarantee adequate behaviour of the entire structural system.