Isolated Rectangular Footings under Biaxial Bending:A Critical Appraisal and Simplified Analysis Methodology

Abstract

The case of isolated rectangular footings being subjected to eccentric loads along both directions is very conventional as columnsare ordinarily subjected to horizontal loads, vertical loads, and moments simultaneously. Also, its design has not been of much concern forengineers due to the availability of simple mathematical equations for the case when the eccentricity lies within the kern.However, the eccentricity in the case of footings subjected to high biaxial moments normally lies outside the kern area and conventionalanalysis becomes invalid in those scenarios. Various approximate graphical or analytical methods are available for the analysis in this case.It has been observed that most of these developed models for the biaxial bending scenario are based on the same postulation, and thusit commonly leads to confusion among designers about the most effective and straightforward method to follow during design. Therefore,to avoid the possibility of related confusion and to provide more clarification regarding the existing methods, all the available solutions for thedesign of the biaxially eccentric condition are critically reviewed in the present study. Moreover, recommendations are proposed for the use ofa simple method based on a justifiable comparison highlighting the shortcomings in the applications of other available solutions. Additionally,to enhance the computational efficiency of computer-aided studies and manual assessments, a simplified approach to automate the recom-mended procedure for the design of rectangular footings is also developed, and correspondingly a pseudoalgorithm is proposed for its easyimplementation.