SEISMIC PERFORMANCE OF STRUCTURAL CONCRETE BEAM-COLUMN JOINTS DESIGNED IN ACCORDANCE WITH THE PRINCIPLES OF DAMAGE AVOIDANCE

Recent research on jointed unbounded post-tensioned precast concrete frames has demonstrated their superior seismic resistance. Inelastic rotation generated during large earthquake motions is accommodated through gap opening and closing at the beam-to-column connections in the frame. By applying the principles of Damage Avoidance Design(DAD),a steel-steel arm our ed connection has been demonstrated to be effective in protecting the precast elements from damage. The re-centring ability of the un bonded prestressed post-tensioned system allows the building to return to its original un deformed position after the earth quake with negligible residual deformations. A theoretical model is developed based primarily on rigid body kinematics and is validated using the test results. A formulation is also developed based on St Vennants’ principle, to estimate the effective stiffness of the precast concrete beams under bidirectional rocking. Based on the experimental findings, improvements to the steel-steel armoured connection and joint details are proposed.