Clt Two-Way Slabs Fire Resistance Test and Numerical Simulation Analysis

In order to investigate the failure mechanism and fire resistance of cross-laminated timber (CLT) two-way slabs at room temperature and under fire conditions, this paper conducted research on their fire resistance performance and performed refined finite element analysis. It analyzes and tests the temperature distribution, and mid span displacement time curve of CLT two-way slabs in a fire, summarized the failure mechanism of the CLT two-way slabs at room temperature and under fire, and compared it with the one-way slab. The results show that under vertical load, the bottom of a CLT two-way slabs will generate tensile stress. However, as wood is a brittle material, it will not undergo significant plastic deformation when the slab bottom is under tension, unlike the steel bars in reinforced concrete slabs, and will not form plastic hinge lines like reinforced concrete slabs. Compared to one-way slabs, CLT two-way slabs undergo hyperbolic deformation under load due to constraints on all four sides. This leads to a stronger overall cooperative working capacity of the components, with better load-bearing capacity than one-way slabs. The CLT one-way slab immediately fails upon reaching its ultimate bearing capacity at room temperature, while the CLT two-way slab undergoes brittle failure with a gradually decreasing load in a step-like manner. Under fire conditions, if the vertical deformation rate of the CLT one-way slab at mid-span is too high, exceeding the provisions on vertical deformation rate in the fire resistance judgment criteria, the component is declared damaged. If the vertical displacement of the CLT two-way slab at mid-span is too high, exceeding the provisions on vertical deflection in the fire resistance judgment criteria, the component is declared damaged.