Out-of-plane behaviors of unreinforced and spray polyurea retrofitted one-way masonry infilled walls

Abstract

Unreinforced masonry infilled wall (MIW) is prone to out-of-plane (OOP) crack, bend, and collapse when subjected to OOP quasi-static and blast loadings. Spray polyurea (SPUA) is an excellent retrofitted material for MIW to improve its blast resistance and reduce fragmentation. Aiming to study the OOP behaviors of one-way unreinforced and SPUA retrofitted MIW under quasi-static and blast loadings, the corresponding OOP resistance functions of MIW under uniform loading are firstly established. The critical collapse deflection of unreinforced MIW is determined as δ = t-a, and the ultimate deflection of SPUA retrofitted MIW depends on the fracture strain of SPUA. Then, the quasi-static OOP uniform loading test on two full-scale one-way MIW was performed, and the OOP loading-deflection curves of MIW were obtained. It indicated that MIW is divided into two parts by the mid-height horizontal crack, and the upper and lower parts are rotated around the top and bottom mortar joints. Furthermore, by comparing with the present and existing quasi-static test data on unreinforced and SPUA retrofitted MIW, as well as the specified resistance functions by regulations (UFC 3-340-02, Eurocode 6, FEMA 306/356) and previous scholars, the applicability of established OOP resistance functions is validated. Finally, the equivalent single degree of freedom (SDOF) calculation approach to predict the dynamic responses of one-way unreinforced and SPUA retrofitted MIW under blast loadings is proposed based on the established resistance functions. The comparisons with five series blast tests demonstrate that the proposed SDOF approach can well predict the OOP deflection of MIW and evaluate whether the wall collapses or not. This work can provide a helpful reference for the blast-resistant evaluation and design of unreinforced and SPUA retrofitted MIW.