Experimental Study on Seismic Performance of Confined Masonry Walls With Window Openings Strengthened by Using Hybrid-Fiber Modified Reactive Powder Concrete

Abstract

Unreinforced masonry structures are vulnerable to seismic action, especially with window openings. Therefore, a strengthening technique needs to be proposed to improve the seismic performance of the confined masonry walls with window openings. In this study, hybrid fibers modified reactive powder concrete (HFMRPC) with good composite action to masonry walls were obtained through material tests. Then, the HFMRPC material was used as a coating to strengthen or repair the confined masonry walls with window openings by single-sided full coverage, double-sided full coverage, single-sided coverage in piers, and double-sided coverage in piers. To investigate the effect of HFMRPC coating on strengthening or repairing the confined masonry walls with window openings. Seven half-scale masonry walls were tested under in-plane quasi-static horizontal loading. The results indicated that the retrofitting technology using HFMRPC coating could effectively enhance the load-bearing capacity, energy dissipation capacity of the strengthened and repaired masonry walls and delay their stiffness degradation. Among the above-mentioned strengthening methods, the strengthening in piers significantly enhanced the ductility and energy dissipation of the specimens, and the double-sided full coverage enhanced the load-bearing capacity and stiffness of the specimens. Finally, a simplified analysis method was proposed to calculate the shear bearing capacity of the strengthened or repaired confined masonry walls with window openings based on theoretical analysis and test results.

Seismic Performance of Assembled Beam–Column Connections with Modified Reactive Powder Concrete under Different Steel Fiber Types in the Critical Cast-in-Place Regions

“…Polypropylene (PP) fibers can dissipate energy through deformation and extraction, which further improves concrete's toughness [31]. The hybrid effect between two fibers improves MRPC's seismic performance [21].…”

“…In addition, the strength difference between the MRPC and the concrete should not be too large, considering the workability and strength requirements of MRPC materials comprehensively. In the previous investigation of the research group [21], the selected steel fiber content was 1.5%, and the optimal mix ratio of MRPC is shown in Table 3.…”