New Self-Centering Tension-Only Brace Using Resilient Slip-Friction Joint: Experimental Tests and Numerical Analysis

Abstract

This paper introduces and provides the experimental results related to a new self-centering steel tension-only brace with energy dissipation characteristics. The introduced brace has nonpinching behavior with no stiffness and strength degradation because of the performance of the resilient slip friction joint (RSFJ) at the brace end(s). These features can ascertain structural damage-avoidance criteria for building performance to minimize the need for retrofitting, demolishing, and rebuilding of structures after earthquakes. Quasi-static and dynamic tests were carried out on a full-scale, two-dimensional steel frame with a height of 3.1 m and a length of 5.05 m. The designed joints and frame were capable of accommodating a 5% lateral drift as the limit for a maximum earthquake (MCE), which was twice the 2.5% limit considered for the ultimate limit state (ULS). The test observations indicate that the frame response was fully repeatable, self-centering, and energy-dissipative. Dynamic effects were observed and resulted in an increase in the slipping force of the system and not in the maximum force. Die-springs were used to minimize these effects. Additionally, a numerical study was performed on a prototype building that was designed elastically using the equivalent static method (ESM) and a ductility of 1.25 to illustrate the ability of the introduced system to reduce the seismic base shear of a conventional tension-only braced structure that can be considered for retrofitting purposes. For this, the RSFJ tension-only braces were designed for 1.5% and 2% drift limits of the structure and considering a ductility of 3 for both cases. Pushover and nonlinear time history analyses were conducted to design the RSFJs. The results indicated that, in both cases, the RSFJ tension-only braces could significantly reduce the base shear by providing ductility greater than 3. From the experimental and numerical studies in this research, the conclusion can be reached that this new bracing system can provide dependable low-damage structural solutions for new and existing structures through the provided damping and self-centering.