Experimental and numerical studies on friction energy-dissipating combination chord of staggered truss

Abstract

Staggered truss framing systems have the problem of insufficient energy dissipation capacity in high intensity areas. To improve this situation, this paper proposes to replace the top chord of the staggered truss with a combination chord for frictional energy dissipation. Two groups and a total of four 1:2 scaled friction energy-dissipating combination top chord specimens were designed and fabricated, and hysteretic performance tests were carried out on them under low cycle reciprocating loads. It was investigated how high-strength bolt pre-tightening force and bolt layout affected the capacity of the combination chord to dissipate energy. The experimental results show that the hysteresis curve of the combination top chord for friction energy dissipation almost presents an ideal rectangle, and its energy-dissipating capacity is very strong. The combination top chord's capacity for friction energy dissipation increases with the increasing pre-tightening force of the high-strength bolt, but its stability for energy dissipation decreases. When the bolt layout is the staggered arrangement of single and double bolts, the initial energy dissipation and cumulative energy dissipation are weaker than that of the uniform arrangement of double bolts. Then, the friction energy-dissipating staggered truss with a sliding bottom chord was proposed to improve the load state of the diagonal web member in the staggered truss. The numerical simulation results show that the overall energy dissipation capacity and lateral bearing capacity of the staggered truss with the bottom chord sliding are 4.0% and 24.5% higher than those of the staggered truss with the top chord sliding.