Abstract:
The Alternate Load Path Method (APM) that is
presented in several standards is the widely followed method for
the assessment of progressive collapse potential. In particular,
the Linear Static APM is popular since it is simple and easy to
implement compared to nonlinear methods. Although nonlinear
approaches can give us a wider range of structural responses,
they are not widely used since they involve complex procedures.
We present here a nonlinear dynamic analysis approach for the
post column loss behaviour in buildings that combines the
simplicity of the linear methods with the comprehensiveness of
the nonlinear ones. The method involves defining a special hinge
that captures the specifications of the General Services
Administration (GSA) guidelines, and reduces the complexities
involved in nonlinear procedures. In addition to the collapse
potential, the method is able to obtain the point of collapse
initiation, collapse path and final extent of collapse relatively
easily. A 3D concrete moment resisting frame under the short
side face middle column removal case yielded similar results to
the linear APM recommended by the GSA guidelines; but the
proposed method was also able to identify that failure was
initiated with the double spanned beam directly over the
removed column yielding in flexure and progressed upwards,
finally resulting in an overall collapse of all beams on the short
side face that frame into the columns vertically in line with the
removed column.
