Numerical derivation of averaged material properties of hollow concrete block masonry

Homogenization technique has been used to derive equivalent material properties of masonry units for many years. However, most of the previous research work concentrated on derivation of equivalent material properties for solid brick masonry structure. Very few studies have been conducted to investigate complex mechanical properties of hollow concrete block masonry unit. In this paper, homogenization technique with engineering approach is utilized to derive equivalent material properties from a three-dimensional basic cell of hollow concrete block masonry. In the numerical analysis, a damage model based on the concept of fracture-based damage and stiffness degradation in continuum damage mechanics is applied to modeling the failure of mortar joint and concrete. Two damage variables, one for tensile damage and the other for compressive damage, are introduced to account for the different damage states. The damage model is implemented into a finite element program to derive the equivalent material properties of hollow concrete block masonry. In the basic cell, hollow concrete block and mortar are separately discretized and nonlinear material properties of mortar and concrete are modeled in details. By applying various displacement boundaries on the basic cell surfaces, the equivalent stress-strain relations of hollow concrete block masonry unit are obtained from the numerical analysis. The averaged material properties and failure characteristics of the hollow concrete block masonry unit are then derived from the numerical results. They are then used to model the dynamic response of a hollow * Corresponding author. Tel: 61-8-83034834. Email address: [email protected] 2 concrete masonry panel subjected to airblast loading and the same masonry panel is also analyzed with the distinctive material model in which mortar and brick are modeled individually. The efficiency and accuracy of the simple homogenized 3D model are demonstrated.