Development of small-scale buckling-restrained brace analog for physical experiments of structural systems

Abstract

Experimental testing is critical for evaluating the performance of novel structural systems. However, the cost of full-scale testing can be limiting. Small-scale testing provides a lower cost alternative that can produce reliable data if each component of the scaled model is properly developed. Given their stable hysteretic behavior, buckling-restrained braces (BRBs) are featured in several seismic force-resisting systems. The design of typical BRBs involves an axially yielding steel core that is prevented from buckling by a concrete casing. Designs for adaptable and easy-to-implement small-scale BRBs that can be included in structural testing have not been established. In this work, a small-scale BRB analog is developed that utilizes a core steel yielding plate that is prevented from buckling by a pair of steel casing plates. A flexural yielding mechanism is employed in the small-scale BRB analog, which allows for practical dimensions and the ability to independently tune brace stiffness and strength. Prototype braces were fabricated and validated through quasi-static cyclic testing in which they exhibited the full and stable hysteretic behavior characteristic of BRBs. To aid in the use of this BRB analog by others, numerical results were utilized to generate empirical equations that relate the strength and stiffness of the scaled BRB to the archetypical geometry of the core plate. Given its ability to deliver a stable hysteretic performance, the wide range of strength and stiffnesses that it can provide, and its easy reusability, the developed device is a good choice for experiments where a small-scale BRB analog is needed.