DEVELOPMENT AND EXPERIMENTAL TESTING OF STEEL POST-TENSIONED CONNECTIONS WITH INNOVATIVE SEISMIC ENERGY DISSIPATERS

摘要

A new self-centering beam-to-column connection is proposed. The connection uses post-tensioned highstrength steel bars to provide self-centering capability and carefully designed energy-dissipation elements (EDs) that consist of steel cylindrical pins with hourglass shape. The proposed EDs: 1) have superior energy dissipation and fracture capacity; 2) are placed between the upper and the bottom flanges of the beam so that they do not interfere with the composite slab; and 3) can be very easily replaced if damaged. A simplified performance-based procedure was used to design the proposed connection. The connection performance was experimentally validated under quasi-static cyclic loading. The specimens were imposed to drift levels beyond the expected design ones in order to identify all possible failure modes. The experimental results show that the proposed connection exhibits stable self-centering behavior by eliminating residual drifts, sufficient energy dissipation capacity, and strength and stiffness comparable to those of a conventional moment connection. In addition, repeatable tests on a connection specimen were conducted along with replacing damaged EDs. These repeatable tests show that the proposed connection can be very easily repaired after a major earthquake without disturbing building use or occupation. In particular, the proposed EDs were easily replaced without using bolting or welding. A simplified analytical procedure using plastic analysis and simple mechanics was found to predict the connection behavior with sufficient accuracy.