Steel beam responses under blast loading

Abstract

The behavior of structural members subjected to blast loads is of important concern in the assessment of structural safety. For beams subjected to blast loads that are characterized by high magnitude pressure and short duration, and distributed along the length, the structural response is dominated by wave propagation and transient member vibrations. The initial wave propagation phenomenon is often neglected in the conventional structural dynamic analysis. However, it has been observed experimentally that failure is often initiated by direct shear failure at the supports and occurs shortly after load application. In this thesis, direct shear failure of a ductile structural member is investigated based on Timoshenko beam theory where shear deformation and rotary inertia are accounted for. The objective is to provide a good understanding of the elastic and the plastic shear wave propagation phenomena in the development of internal shear force and moment, so as to gain insight for describing the incipient failure modes. The study is carried out analytically and numerically. Attempts are also made to address on the time scale of imposed blast loads over which wave propagation or structural dynamics dominates.