Support stiffness effect on tall load bearing masonry walls.

摘要

This research investigates the behavior of tall masonry walls under the influence of reactive support stiffness. Current design practice does not recognize the effect of actual support stiffness in estimating masonry block wall load capacity and ignoring this effect leads to underestimated wall capacity. This indicates the need to evaluate the actual boundary conditions and to investigate the behavior of masonry tall walls in the context of actual boundary conditions.; The research has three main phases. The first phase encompasses the evaluation of support stiffness as a function of footing dimensions and supporting soil properties and then to simulate this support stiffness in a full scale testing setup. The support stiffness of commonly used strip footing foundations was evaluated for a variety of footing dimensions and soil properties. A full scale testing setup was designed by simulating the different levels of support stiffness. Eight wall specimens were tested into two groups with slenderness ratios of 28.6 and 33.9. All walls were loaded with a common load eccentricity ratio of 0.33. The test results were analyzed to study the effect of support condition on load capacity as well as on Flexural rigidity of the tested walls. The test results were found consistent.; In the second phase all wall specimens were modeled using a nonlinear finite element macro modeling approach. ABAQUS Explicit V 6.3 was used for analysis. The non-linear finite element model was verified against the test results and found satisfactory. The model was then employed to perform a comprehensive parametric study. The support stiffness was considered a primary parameter and was combined with other geometric and material parameters. The axial capacity and the flexural rigidity of the walls were investigated under the coupled effect of these parameters.; In the third and final phase of the research, the results obtained from parametric study were utilized and non-linear regression analysis was performed. Two sets of equations to estimate the axial load capacity and the effective flexural rigidity under the effect of reactive support condition were obtained. Validity of proposed mathematical expressions was assessed using available experimental results and found satisfactory.