Behavior of Square Infilled Frames

An investigation of the behavior of diagonally-loaded square infilled frames is described first. Series of experiments on diagonally-loaded models with a range of frame stiffnesses indicated that a small increase in frame stiffness has a magnified effect on the over-all stiffness and strength of the structure. Approximate theoretical analyses, based on the length of contact between the frame and infill, are developed to explain this composite behavior, and to provide methods of predicting the over-all diagonal stiffness and strength. The behavior of laterally-loaded infilled frames is considered next. The methods proposed for the diagonally-loaded case are adapted to predict the lateral stiffness and strength of single or multi-story square infilled frames. The results of experiments on single and double-story models support the pro-posed methods of prediction.