Reduced-Order Modeling of Composite Floor Slabs in Fire. II: Thermal-Structural Analysis
Publication: Journal of Structural Engineering
Volume 146, Issue 6
Abstract
This paper describes a reduced-order modeling approach for the thermal and structural analysis of fire effects on composite slabs with profiled steel decking. The reduced-order modeling approach, which uses alternating strips of layered shell elements to represent the thick and thin portions of the slab, allows both thermal and structural analyses to be performed using a single model. The modeling approach accounts for: (1) the trapezoidal profile of the concrete in the ribs; (2) the structural resistance provided by the steel decking, including the webs of the decking; and (3) the orthotropic behavior of the decking, which provides greater resistance along the ribs than transverse to the ribs. The modeling approach is validated against experimental data from one-way composite slabs tested under ambient-temperature, a one-way composite slab tested under fire conditions, and a two-way composite slab tested under fire conditions. Both implicit and explicit solution schemes are evaluated for the structural analysis, and the results show that it is feasible to scale down the hours-long fire duration to a simulation time of seconds in an explicit dynamic analysis, without adversely affecting the accuracy of the results. The steel decking contributes significantly to the structural resistance at an ambient temperature, but as expected, its contribution is found to decrease rapidly under fire exposure. The modeling approach can account for the location of reinforcing bars (i.e., at a specified depth in either the thick or thin portion of the slab), and it is found that reinforcement location can have a significant effect on the structural response, because heat transfer in the composite slab results in higher temperatures in the thin portions of the slab between the ribs.
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Disclaimer
Certain commercial entities, equipment, products, or materials are identified in this document in order to describe a procedure or concept adequately. Such identification is not intended to imply recommendation, endorsement, or implication that the entities, products, materials, or equipment are necessarily the best available for the purpose. The policy of the National Institute of Standards and Technology is to include statements of uncertainty with all NIST measurements. In this document, however, measurements of authors outside of NIST are presented, for which uncertainties were not reported and are unknown.
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Published In
Journal of Structural Engineering
Volume 146 • Issue 6 • June 2020
Copyright
©2020 American Society of Civil Engineers.
History
Received: Apr 24, 2019
Accepted: Oct 15, 2019
Published online: Mar 19, 2020
Published in print: Jun 1, 2020
Discussion open until: Aug 19, 2020
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