Volume 4, Issue 5 (May 2007)
Inelastic Dynamic Response of Curtainwall Systems to Blast Loading
Blast-resistant curtainwall systems require laminated glass that is adequately adhered to the mullions to develop the membrane capacity of the glass, as well as mullions that are capable of transferring the collected forces to the structural slabs. Dynamic inelastic analyses are required to determine the response of curtainwalls to highly impulsive blast loading. The most economical way to minimize the hazard to occupants is to allow the glass to undergo large deformations prior to dismemberment and fragmentation. Curtainwall performance is often evaluated using a sequence of single-degree-of-freedom (SDOF) analyses. The glass is represented as an SDOF to determine the reaction forces, which are then applied to SDOF analyses of the mullions. These individual calculations represent the dynamic inelastic response of the glass and mullions, but often neglect their interaction and phasing. As a result, SDOF methods tend to overpredict the response of the curtainwall components, resulting in an uneconomical design. Dynamic inelastic finite element analyses that account for the interaction of the glass and mullions and accurately represent the potential failure mechanisms provide the most accurate evaluation, leading to the most economical design for blast-resistant curtainwall systems. In addition to material nonlinearities, the finite element analyses also account for geometric stiffening of the components, therefore producing more accurate anchorage forces to be developed at the slabs.