There is increasing recognition that conventional ductility-based design of structures for collapse prevention may not be sufficient in a modern society that demands higher-performing alternatives. Such a reality has motivated research on structural systems that minimize the disruption and cost of repairs following major earthquakes. This paper presents the experimental investigation of an asymmetrical moment-resisting connection that concentrates damage in replaceable angles at the bottom flange, achieving a repairable connection in the presence of a concrete slab. A total of three full-scale subassemblies of beam-to-column composite connections were tested with two different types of angle configurations: reduced section angles and end-reinforced angles. The results demonstrated that the proposed asymmetrical connection exhibited a stable and full hysteretic behavior up to 0.036 rad story drift. The replaceability of the bottom angles was confirmed during the tests, and the replaced specimens showed a strength of 0.8 times the original strength at the initial stage, increasing to 0.95 after 0.015 rad. The angles were replaced after specimens experienced drifts up to 0.02 rad for this asymmetrical connection with similar subsequent performance. Although evident buckling of angles was observed, the strength degradation from one cycle to the next was 0.93 up to approximate 0.04 rad story drift. There was a negligible stiffness decrease in the asymmetrical connection compared with the same continuous composite beam when the moment capacity ratio was 0.5 or greater.

This paper presents a novel type of hybrid self-centering braces incorporating tension-only superelastic NiTi shape memory alloy (SMA) cables and integrated viscoelastic dampers (VEDs). One of our reasons for proposing this new SMA-viscoelastic hybrid brace (SCVEB) is to provide enhanced energy-dissipation ability whilst promoting increased self-centering tendency compared with the existing SMA-based self-centering solutions, where upgrading behavior is mainly benefited from the participation of the VEDs. The configuration and the working principle, along with theoretical equations describing the mechanical behavior of the SCVEB, are described in detail firstly. Experimental verification of individual elements in this SCVEB system, namely the NiTi SMA cables and VEDs, was performed to obtain a basic understanding of their mechanical properties. A proof-of-concept SCVEB specimen was then manufactured, and its cyclic performance was further investigated. Followed by this, a system-level analysis on a series of steel frames equipped with or without SCVEB was conducted. The results showed that the SCVEB system exhibited a moderate damping ratio and a more efficient controlled behavior in terms of its post-event residual deformation and floor acceleration when compared with those of the non-SCVEB system.