Experimental studies on structural performance of precast concrete shear walls with innovative UHPC-based connections

Abstract

Ultrahigh-Performance Concrete (UHPC) is an advanced class of cement-based composite that offers excellent bond performance with steel bars. When compared to conventional approaches, using UHPC-based connections for Precast Concrete Shear Walls (PCSWs) has the advantages of smaller bar lap-spliced lengths and greater tolerance to installation errors. In this study, a two-stage scheme was proposed. Firstly, the bond properties between lapped steel bars and UHPC were determined to provide guidelines for designing PCSWs. A total of 15 pullout samples were designed and tested under direct tension. Failure patterns including steel bar pullout, cover splitting, and steel bar rupture were summarized. The basic splice length of steel bars with diameters limited to 14 mm in UHPC should be at least 6 times the bar diameter. In the second stage, the seismic performance of PCSWs with UHPC-based connections was investigated. Two full-scale PCSWs and two monolithic walls were constructed and tested cyclically in axial compression ratios of 0.1 and 0.3. In PCSWs, the splice length of additional bars (the one-row) in UHPC was set as 10 times the diameter to allow for a safe margin. PCSWs with UHPC-based connections demonstrated higher load-carrying capacity, better ability to dissipate energy, and comparable ductility to monolithic counterparts. An evaluation of test results also met the acceptance criteria for shear wall systems that could be considered as structures assigned to high seismic performance.