Parametric Study on Slenderness Ratio of Concrete walls With Openings

Abstract

Available studies have illustrated the conservative nature of empirical wall design equations provided in major codes of practice such as AS3600 and ACI-318. Furthermore these equations fail to recognise walls that are supported on all four sides, walls with slenderness ratios greater than 30 and walls that require openings for doors, windows or services. The recognition of such factors in design codes would result in improved designs through more efficient material use and subsequent savings in construction costs.

The objective of this study is to investigate the effect of slenderness ratio and the presence of openings for reinforced concrete wall panels loaded axially where an eccentricity induces secondary bending. A numerical analysis of such walls is undertaken using the non-linear Layered Finite Element Method (LFEM). The LFEM takes into account all bending, membrane and shear deformations of structures and is capable of modeling vertically oriented structural elements such as walls.

Eight half-scale wall panels tested previously at Griffith University form the basis of a comparative study. These walls have one or two openings, are supported either at the top and bottom or on all four sides, and have slenderness ratios of 30 and 40. Minimum reinforcement is placed centrally and panels are loaded axially with an eccentricity of tw/6. The accuracy of the LFEM in predicting the failure loads, the load-deflection responses, the deformed shapes and the crack patterns of the tested wall panels is demonstrated. The establishment of a benchmark model enabled parametric studies on a total of 24 new wall panels investigating the effects of slenderness ratio (of 10, 15, 25, 30, 40 and 50) on the ultimate load capacity of one-way and two-way reinforced concrete walls with openings. Relationships of axial strength ratio with slenderness ratio are also established.