Blast response of one-way arching masonry walls

Abstract

The dynamic response of arching unreinforced masonry walls subjected to blast loads combines a spectrum of complex physical phenomena including opening and closing of cracks, unloading and reloading, accumulation of damage, rocking, coupling of in-plane and out-of-plane responses, and time variation of the arching force. These aspects contribute to the complexity of the dynamic behavior of the masonry wall and make the dynamic analysis challenging. This study develops a new model that integrates the aforementioned characteristics of the wall behavior and presents a quantitative tool for the assessment of the complex response. The model assumes one-way flexural action of an unreinforced masonry wall and takes the form of a multi-degree-of-freedom system, where the response is described by the displacements and rotations of the masonry units. The formulation employs variational principles and accounts for equilibrium conditions, cracking, geometrically nonlinear kinematics, and nonlinear and inelastic constitutive laws. The masonry units are assumed rigid bodies, whereas the flexural longitudinal and shear deformations of the wall are due to the mortar strains only. The mortar joints and the interfaces between adjacent masonry units are represented by arrays of nonlinear longitudinal and shear springs that introduce the normal, shear, and contact interactions between blocks. The model is examined and compared against experimental results taken from the literature. The investigated features include the cracking process, the inelastic behavior of the mortar material, and its effect on the wall response. The results demonstrate the capabilities of the analysis and throw light on the dynamic nonlinear response of the arching masonry wall under blast loads.