Blast-resistant analysis and design of CFRP sheet strengthened masonry infilled walls

Aiming to investigate the performance and design approach of the carbon fiber reinforced polymer (CFRP) sheet strengthened masonry infilled walls subjected to blast loads, the commercial finite element program LS-DYNA is firstly used to develop the simplified micro-finite element model of masonry infilled walls and the corresponding blast-resistant analysis model of CFRP sheet strengthened walls. By comparing with the nine groups field explosion test results of unstrengthening and CFRP sheet strengthened masonry infilled walls, the applicability of the present simplified micro-modeling approach, as well as the material models and parameters of masonry and CFRP sheet, is verified. Furthermore, referring to the CFRP seismic strengthening methods recommended by Chinese standard GB 50608-2020, the dynamic behaviors of the prototype masonry infilled walls strengthened with CFRP sheets under blast loads are analyzed and compared. It is recommended to prioritize the diagonal two-way strengthening method, followed by vertical two-way and horizontal full-cover strengthening methods, and vertical full-cover and mixed three-way strengthening methods are not recommended. Finally, to simultaneously satisfy the CFRP is basically intact, no scattering debris and the peak central deflection less than wall thickness as the blast-resistant design goal, the ranges of scaled distance of prototype masonry infilled walls with different arrangements of tie bar (non-/cut-off/full-length tie bar) that need to be strengthened under typical sedan (227 kg equivalent TNT) and briefcase bombs (23 kg equivalent TNT) explode at different scaled distances are determined as 0.8-2 m/kg1/3 and 0.2-1.2 m/kg1/3, respectively. The suggestions for the optimal number of CFRP sheet layers for blast-resistant design are further given.