Sensitivity of composite floor system response at elevated temperatures to structural features
Therese P. McAllister
The sensitivity of composite floor system response at elevated temperatures to variations in structural features is examined. Four structural features were varied between two values or conditions, based on a recommendation from the NIST investigation of the WTC 7 collapse. The four structural features were varied between the two values in a sensitivity study based on a 2^4 factorial design. The effect of the four parameters, as well as their interaction effects, is evaluated relative to the average response for all combinations through both time to onset of damage and time to first failure. The results of the 16 analyses are presented in terms of time to damage onset and failure. Parameters that affected the response by more than 0.5 h were considered to have a significant effect on the floor system response to fire. Parameters that affected the response by 0.2 h up to 0.5 h were considered influential. Of the four structural features varied in the analyses, floor beam length most affected the structural response of the floor system, sometimes changing the time to damage onset or first failure by more than 0.5 h. The other three features, the presence or absence of girder studs, connection type (single or double shear), and one- or two-sided girder framing, influenced the structural response by 0.2 h up to 0.5 h. Interaction effects also influenced the structural response, indicating that the structural features cannot be evaluated independently.