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.
