Experimental study on fire endurance of CLT-concrete composite slabs exposed to one-side fire

To investigate the fire endurance of CLT-concrete composite slabs in fire, four CLT-concrete composite slab specimens and two CLT slab control specimens were designed and tested at normal temperature and in fire, respectively. Numerical simulation of the specimens was also conducted. The test results indicate that the failure modes of the CLT slab specimen at normal temperature basically include tensile failure along the grain of the bottom dimension lumbers, transverse grain splitting failure between the two adjacent layers of dimension lumbers, and rolling shear failure of the middle dimension lumbers. The failure modes of CLT-concrete composite slab specimen at normal temperature include shear failure at the interface between the cast-in-place concrete layer and the CLT panel, and tensile fracture failure of the bottom dimension lumbers along the grain. The initial stiffness and bending capacity of the CLT-concrete composite slab specimen at normal temperature are 237. 8% and 60. 1% higher than those of the CLT slab specimen. After being exposed to fire, there are obvious charring layers in the CLT panels, and the composite slab specimens have obvious bending deformations. Under the same load ratio, the fire endurance of the CLT-concrete composite slab specimen is 335. 3% higher than that of the CLT slab specimen. With the load ratio increasing from 0. 20 to 0. 50, the fire endurance decreases from 74. 1min to 30. 6 min. The finite element model provides good prediction accuracy for the fire endurance of the CLT-concrete composite slab specimens, and the modelling errors are within 14. 1%, which can satisfy the engineering accuracy requirements. © 2024 Science Press. All rights reserved.