Effect of high temperature exposure on design parameters and collapse behavior of reinforced concrete and steel-framed buildings

In many situations, not only vertical loads but also lateral loads are taken into account in the design of frame systems. However, although fires are rare events, determining possible behavior changes with the increasing temperature is important for design process. Therefore, the current study presents a numerical examination of the fire behavior of two different buildings with the same geometric properties. For this purpose, 4-story reinforced concrete (RC) and steel-framed building models with four spans in the x and y directions were created. Two spaces, one at the corner and one in the middle of the ground floor were exposed to heat loading gradually from 25 °C to 1000 °C (100 °C each time). The internal forces and time to critical temperature for the columns in these spaces were determined. Furthermore, the effect of temperature on plastic hinge formation was examined and the effect of high temperatures on the design parameters was identified. The results obtained revealed that among RC and steel buildings exposed to the same heat loading, the RC building maintained its integrity and did not reach the collapse state. However, the steel building reached its critical temperature and collapse state in 60 min.