Estimation of Building Damage Due to Excavation-Induced Ground Movements

Building damage due to excavation-induced ground movement is evaluated using a damage criterion based on the average state of strain in the distorting portion of the structure, and by considering the effect of building shear stiffness on the distortions imposed by the ground settlement profile. Physical model tests and numerical simulations, correlated with case studies of building distortion and damage, have been used to evaluate these relationships for masonry bearing wall structures. The distinct element method was used to numerically model each masonry unit as a block, with the contacts between blocks having the stiffness and strength characteristics of mortar. In-plane displacements at the corners of the wall sections permitted determination of the average state of strain, and the components of rigid body tilt, angular distortion, lateral strain at the base, and the contribution of bending strain to the lateral strain in the upper portion of the wall. The increase in angular distortion with increase in the ratio of ground/structure shear stiffness (decrease in building shear stiffness) was examined for both elastic and cracked building walls. Cracking significantly reduced effective wall stiffness making the wall more conformable to the ground settlement profile, which increased angular distortion, causing it to approach the distortion (change in ground slope) that would occur in the absence of the structure.