Strength capacity of hollow clay blocks structural masonry - Flange, Chases, and slenderness effects

Unplanned chases made in structural masonry for the passage of pipes can compromise the overall strength of the structure. This interference does not have clearly established and uniform criteria in Brazilian and international standards for assessing the deformability and consequent safety reduction of the walls. The present study evaluates numerically, by using the Finite Element Method (FEM) and fitting procedures, the effect of chases in masonry walls elements, proposing a method to preview walls strength reductions with the presence of chases. Thus, an additional criterion for the reduction factor (R) due to the masonry slenderness is presented. The contribution of the flanges is also evaluated for different height/length ratios. The simplified approach of disregarding the chase thickness of the wall determine its slenderness (λ), and consequently the strength reduction factor (R), was invalidated in the present study, considering that the numerical models provided lower reduction coefficients for any wall group studied. The slenderness of the walls considering the residual wall thickness in the chase region must be limited to 33.