<p> A Matrix Stiffness-Modification Technique has been proposed for the inelastic analysis of ·reinforced concrete frames subjected to short term or sustained loads. To check the applicability of the analytical method, two large scale concrete frames were tested under short-term loads and sustained-loads respectively. In addition, data for twenty-two frame tests from other sources has also been compared with the non-linear analysis. Close agreement has. been observed for all the frames considered. It was further concluded that a conventional elastic matrix method using stiffnesses based on a cracked transformed section of concrete does net yield accurate results, especially in the case of sustained loading conditions. From the method developed, comments can therefore be made on present column design practice. </p> / Thesis / Master of Engineering (MEngr)