Precast concrete shear wall systems are becoming increasingly popular for low, medium, and highrise construction due to its economical advantages. The use of such a system is currently very limited in seismic areas because of the lack of understanding of its behaviour under earthquake loading. The seismic behaviour of the precast structure is significantly dependent on the connections between the precast elements. Consequently, it is crucial to understand the behaviour of connections under effects of inelastic cyclic loading conditions which could be induced during an earthquake.

This thesis summarizes an extensive multi-phase experimental program conducted to study the behaviour of horizontal connections for precast concrete shear wall panels subjected to large reversed cyclic inelastic deformations. The program considered the behaviour of connection configurations currently used in practice and investigated new innovative connections believed to enhance the ductility and/or energy dissipation capacity of the connections. Seventeen prototype specimens were tested under quasistatic reversed cyclic shear and reversed cyclic flexural loading to examine fully all aspects of the connection behaviour. A constant stress, applied normal to the connection, was used to simulate the effects of the gravity loads on the structure. In this study, the influence of mild steel reinforcement, post-tensioning bars, post-tensioning strands, multiple shear keys and debonding of continuity elements were investigated. The test results were used to identify the contribution of each component of the connection to the overall behaviour and to define the various limit states cyclic behaviour in terms of strength, stiffness degradation, energy dissipation capacity and ductility.

All the connections tested in this program were able to withstand very large cyclic deformations well beyond first yield. The response of the connection was characterized with stable hysteretic behaviour until onset of failure. The failure mode under cyclic loading was due to extensive crushing and spalling of the drypack, with rupture of the continuity reinforcement at the connection level. The severe drypack deterioration due to cyclic loading was an additional limit state not observed for the specimens tested under monotonic loading conditions. The cyclic loading also significantly influenced the ductility capacity of the connection but had slight effect on the connection strength. The ductility level was reduced by 50% in comparison to identical specimens tested under monotonic loads. Stiffness degradation under cyclic loading was very similar for all connection configurations and was characterized by a sharp decrease in stiffness versus ductility. The residual stiffness was about 20% of the initial stiffness at yield.

It is shown that, for the same configuration, the strength of the connection under pure shear loading is more than twice that under combined flexure and shear loading. The presence of multiple shear keys significantly limits the slip mechanism. The use of prestressing slightly enhances the ductility capacity but significantly reduces the energy dissipation in comparison to the specimens with mild steel reinforcement. The use of unbonded reinforcement significantly enhances the behaviour of the connection in terms of deformation capacity and energy dissipation without significantly influencing the stiffness and strength.

A simple rational analytical procedure is described which predicts strength - deformation envelope of the cyclic response. The strength is determined using conventional methods and the deformation is determined from concentrated rotation at the joint region based on extension of reinforcement. The experimental results compared very well with the predicted response. Based on the findings of the research, design recommendations for connections in seismic zones are presented.