Abstract:
The performance of precast concrete load-bearing walls exposed to fire is investigated using 3-D thermal and structural models. The thermal model is used to obtain the temperature history, which is input as the thermal body load for the structural model in order to predict displacements, crack patterns and stability of the wall. The thermal model is validated by comparing the predicted temperatures with measured data from the fire tests and previous experimental studies, while the structural model is verified by comparing the predicted displacements and crack patterns with those taken from the fire tests. It is found that the results obtained from the thermal and the structural models are in line with the experimental data. The validated model is used to study the effect of load levels, slenderness ratios and boundary conditions on the fire performance of the walls. It is found that the fire resistance rating of the 120 mm thick load-bearing walls decreases by up to 90% with increasing load levels and 93% with increasing slenderness ratios, while the fire resistance rating of the walls increases by up to 94% when the rotational restraints are imposed at the ends of the walls. Simplified equations are also derived for estimating the fire resistance rating of the walls based on the least-squares method. Finally, the fire performance of walls with unsymmetrical restraints and openings are investigated. It is found that the horizontal displacements of the simply supported wall decrease by up to 6% at the center of the wall when the translational restraint is imposed on a vertical edge and increase by up to 36% at the center of the wall when a wall opening is included. Further studies are recommended to investigate the effects of unsymmetrical restraints and openings on the walls with varying configurations.
