Experimental study on seismic performance of two-story two-bay. Precast concrete frame with UHPC-based connections

Abstract

The UHPC-based connections, utilizing Ultra-high performance concrete (UHPC) to connect rebars within precast concrete structures, present the advantages of short splice length, simplified construction, and low cost due to the excellent bond property between UHPC and rebars. This investigation focuses on seismic performance of precast concrete frame (PCF) with UHPC-based connections. The UHPC-based connections were arranged strategically to the beam-column joints and column bases in PCF to connect longitudinal rebars of beams and columns, respectively. Two half-scale, two-story, two-bay reinforced concrete frames, including PCF and a monolithic concrete frame (MCF) for reference, were tested under cycle loading with axial compression ratios of 0.33 in the middle columns and 0.22 in the side columns. The results revealed that PCF exhibited a beam sway mechanism, with all beam hinges developed prior to column hinges, while MCF displayed a mixed sway mechanism, with part of beam hinges developed prior to column hinges. The hysteresis curves of the two frames were globally stable with minimal pinching, and PCF displayed greater energy dissipation compared to MCF. The load-carrying capacity of PCF was 9 % higher than that of MCF. The displacement ductility of PCF was 4.14, exceeding that of MCF by 10 %. The two frames showed similar laws of stiffness degradation. Overall, the precast concrete frame with the UHPC-based connections exhibited better seismic performance in comparison with the monolithic counterpart.