Ultimate Strength Analysis of Normal and High Strength Concrete Wall Panels with Varying Opening Configurations

Abstract

Currently the wall panel design equations given in the Australian Standard and the American Institute Code offer no guidelines for the inclusion of side restraints or openings. Empirical formulae have been derived based upon limited test data, in which only the length and location of openings are accounted for with a dimensionless parameter, αx. In this study the nonlinear Layered Finite Element Method (LFEM) is used to undertake a comparative study to verify the effectiveness of the method in predicting the failure characteristics of seven two-way normal strength concrete walls without and with window and door openings. The ultimate loads, load–deflection responses up to failure, deflected shapes and crack patterns predicted by the LFEM are compared to the experimental observations. The method is then used to conduct three parametric studies investigating the influence of opening size, length and height on the ultimate load and deflection of twenty high strength wall panels acting in both one-way and two-way.

Comparisons of the numerical results to established formula for walls with openings validated the accuracy of the LFEM predictions. Results demonstrate that increase in opening size decreases the axial strength ratio to different degrees for one-way and two-way walls. Increasing only the opening length also significantly decreases the axial strength ratio. Increasing only the opening height has little impact on the ultimate load capacity. Walls analysed in two-way action have an increased strength compared to the one-way counterparts due to the provision of side restraints, however, such improved strength becomes small for a large sized opening. Results further confirm that increasing the opening height together with the length has the most critical effect. Hence to ensure safe design, the combined effects of increasing both the height and length of an opening should be incorporated into the ultimate load formula which is proposed in this study. The results of this study have assisted in verifying the LEFM as a reliable and effective technique for determining a relationship between ultimate load capacity and varying opening configurations so that more dependable design aids and accurate formulae can be established.