Cui, Tang, Wu, Okazaki, Wang 2022
Six different dog-bone shaped steel plate fuses were tested under three loading conditions in order to test the effects of the width to thickness vs. slenderness ratios, cyclic loads of varying amplitudes, and cyclic loads of constant amplitudes for application in steel moment resisting frames (SMRF’s).
System Concept
In this study, an innovative approach to coupling beams used in shear wall and frame-shear wall, known as frictional steel truss coupling beams (FTCBs) system, was investigated in comparison with traditional reinforced-concrete coupling beams (RCCBs). This technology was developed in order to mitigate the costly damage that usually occurs in RCCBs. This is accomplished by incorporating deformation mechanisms of trusses and energy dissipating friction dampers in the new system. Quasi-static tests were performed on specimens of both systems to investigate their seismic performance. The FTCBs exhibited high seismic performance with satisfactory energy dissipation capacity, minimal damage and hysteric behavior.
Experimental Study, Results and Discussion
The novel system integrates a truss configuration that separates shear and bending demands in a pipeline layout. Concentrated rotation is enabled by pinning the chord members of the FTCBs to the wall piers. Two types of this proposed system were introduced in the study: shear-critical FTCBs (SFTCBs) and bending-critical FTCBs (BFTCBs). SFTCBs comprise a smaller span-to-height ratio and friction dampers in the diagonal webs of a singular truss panel, whereas, BFTCBs comprise a larger span-to-height ratio and friction dampers in bottom chords. This enables the system to resist both shear-critical and flexural-critical deformation mechanisms. Flexural force is resisted by chords and shear force is resisted by the diagonal web members. In addition, sliding friction dampers on either the diagonal webs or chords ensure that inelastic damage is restricted to only replaceable material, avoiding damage to truss members. Friction dampers comprise disc springs, high strength bolts, cap plate, steel shims and brass shims. The member that is most prone to large deformation during an earthquake should be considered when choosing the type of FTCBs.
Reference
Cui, Yao, et al. “Mechanism and Experimental Validation of Frictional Steel Truss Coupling Beams.” Journal of Structural Engineering, vol. 148, no. 9, Sept. 2022, p. 04022129. DOI.org (Crossref),