Progressive Collapse of Reinforced Concrete Frame Structure Under Column Damage Consideration

Abstract

In this research work progressive collapse analysis of reinforced concrete framed structure is carried out under column damage consideration by using commercial software SAP2000. The term ‘progressive collapse’ means the ultimate failure or proportionately large failure of a portion of a structure due to the spread of a local failure from element to element through-out the structure. A building frame having nine stories with six bays in longer direction and three bays in shorter direction is selected. Various types of analyses are performed which includes the linear static analysis, non-linear static analysis and nonlinear dynamic analysis. The frame is subjected to loading as described by GSA guideline. The frame is analyzed under three damage cases which include corner column damage, edge column damage and internal column damage. The results include the variation of bending moment of beams, axial forces in columns, and hinge states in nonlinear static and dynamic analysis at front and side elevation of the frame. The demand capacity ratio for beams, deflection at the critical joints and hinge states are evaluated in all the analysis cases with 40%, 60%, 80% and fully damaged consideration. It is concluded edge column case with long bays are found critical in the event of progressive collapse because the bays with longer span experience more damage than smaller span as it is seen in linear static analysis. This indicates that the building can fall in short interval of time and there is more possibility of loss of lives in such type of buildings. It is mandatory to control the deflection under the damaged joint because large deflection will cause collapse of the structure. The results show that deflection at the edge is 46% higher than corner and 47% higher than internal column. In nonlinear static and dynamic analysis the potential for progressive collapse does not exist because the formation of hinges of beams and columns are at their initial level and no hinge is fully developed. Based on this research it is suggested that the practicing engineer should incorporate the GSA guidelines for loading along with the other loads so that progressive collapse potential may be reduced up to some extent.