Fire Resistance Test of a Reinforced Concrete Beam-Supporting Column Transfer Structure Joint Unit

摘要

According to the characteristics of a reinforced concrete beam-supporting column transfer structure, two types of beam-supporting column joint unit specimens are designed, and fire resistance tests are conducted on the specimens. Adopting the ISO 834 international standard heating curve for temperature control, the temperatures at the measuring points on the concrete and rebar inside each joint unit specimen and the vertical deformation at the feature position of each joint unit specimen are recorded, the corresponding curves are drawn, and the fire resistance rating is obtained. After the specimens are naturally cooled, the damage to the specimens after reaching the fire resistance rating is observed. The experimental results show the following attributes: After the reinforced concrete beam-supporting column transfer structure joint unit specimen reaches the fire resistance rating, the bending deformation of the transfer girder becomes more concentrated; the damage modes of the beam sections are bending failure; the cracks are largely located approximately 400-500 mm from the maximum bending moment section; and the longitudinal rebar in the crack section of the transfer girder could break under high temperatures. Under the coupling of fire with a constant load, the distribution of internal forces along the axis of the transfer girder changes, causing the girder to deform differently on the two sides of the supported column. Therefore, the influence of a change in the internal force distribution on the fire behavior due to the arrangement of the supported column must be considered.