MACROSCALE MODEL CALIBRATION FOR SEISMIC ASSESSMENT OF BRICK/BLOCK MASONRY STRUCTURES

The accurate prediction of the response of masonry structures under seismic loading is one of the most challenging problems in structural engineering. Detailed heterogeneous models at the mesoor microscale, explicitly allow for the specific bond and, if equipped with accurate material models for the individual constituents, generally provide realistic response predictions even under extreme loading conditions, including earthquake loading. However, detailed mesoor microscale models are very computationally demanding and not suitable for practical design and assessment. In this respect, more general continuum representations utilising the finite element approach with continuum elements and specific macroscale constitutive relationships for masonry assumed as a homogeneous material represent more efficient but still accurate alternatives. In this research, the latter macroscale strategy is used to model brick/block masonry components structures, where a standard damage-plasticity formulation for concrete-like materials is employed to represent material nonlinearity in the masonry. The adopted material model describes the softening behaviour in tension and compression as well as the strength and stiffness degradation under cyclic loading. An effective procedure for the calibration of the macroscale model parameters is presented and then used in a numerical example. The results achieved using the calibrated macroscale model are compared against the results of simulations where masonry is modelled by a more detailed mesoscale strategy. This enables a critical appraisal of the ability of elasto-plastic macroscale nonlinear representations of masonry modelled as an isotropic homogenised continuum to represent the response of masonry components under in-plane and out-of-plane earthquake loading.