A Study on the Effectiveness of Bracing System for Lateral loading

An attempt has been made to study the reduction in responses of a structure under lateral loading due to the incorporation of a bracing system. In practice a building structure is subjected to eccentric loading due to the placement of different nonstructural elements within and above the structure. Due to the effect of eccentric loading a building normally experiences lateral as well as torsional displacement under seismic loading. Bracing system in any form increases the overall stiffness of the system and hence acts as a control mechanism for both lateral and torsional movement of the structure. In this study a single storey steel frame model is analyzed in a shake table for three different loading conditions namely frame without any extra mass, frame with a central mass and frame with an eccentric mass. A pair of X bracing system is then introduced to the structure and analyzed for the same three conditions. Comparisons are made for different responses namely lateral displacement, velocity, acceleration and torsional movement of the frame at roof level with and without bracing system. From the study it is clear that the bracing system is effective for reducing the lateral movement as well as the torsional effect to a great extent. Model study shows that a bracing system results in a reduction in the displacement at roof level up to about 80% as compared to that of an unbraced frame