Large-Scale Experimental Validation of Steel Posttensioned Connections with Web Hourglass Pins

Abstract

A new self-centering beam-to-column connection is proposed. The connection uses posttensioned high-strength steel bars to provide self-centering capability and carefully designed energy-dissipation (ED) elements that consist of steel cylindrical pins with an hourglass shape. The proposed ED elements have superior ED and fracture capacity, and are placed between the upper and the bottom flanges of the beam such that they do not interfere with the composite slab. 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 to identify all possible failure modes. The experimental results show that the proposed connection eliminates residual drifts and beam damage for drifts lower than or equal to 6%. A simplified analytical procedure using plastic analysis and simple mechanics was found to accurately predict the connection behavior. Repeated tests on a connection specimen were conducted, along with replacing damaged ED elements. These tests showed that the proposed ED elements can be easily replaced without welding or bolting, and hence the proposed connection can be repaired with minimal disturbance to building use or occupation in the aftermath of a major earthquake.