Experimental Study On Physical And Mechanical Properties Of Wood After High Temperature

There are a large number of ancient wooden structures in our country which have important historical heritage value.Its long-term preservation is a daunting task. A lot of magnificent ancient buildings such as A fanggong and Summer Palace disappeared or destroyed in the fire because of it's flammability.When to repair non-severely damaged old buildings,taking into account the ancient buildings must follow the "do not change the historic condition, repair old as" repair principle, we usually continue to use the lighter destroyed wood components.Mastering the physical and mechanical properties of wood is very important because the physical and mechanical properties will change significantly after high-temperature.Larch wood commonly used in the ancient timber structure of our country will be used for the research.Through the experimental study on the physical and mechanical properties of larch wood after high temperature,the influence laws of maximum temperature,constant temperature time and cooling mode have been analyzed.The results indicates that,(1)With the temperature and holding time increasing, the moisture content of the wood gradually reduced,the mass loss of timber increased,the color gradually became light brown, and then dark brown. The color changed significantly at 200 ?- 250 ?.(2)The main mechanical properties [Compressive strength parallel to grain,Compressive modulus of elasticity parallel to grain,Tensile strength parallel to grain,Shear strength parallel to grain(Tangential direction),Stripes whole surface compressive(Radial direction),Stripes compressive modulus of elasticity(Radial direction)]alldecreased after high temperature, the degree is effected by temperature,holding time and cooling mode.The temperature is the most important factor.(3)Stochastic damage constitutive rmodels including tensile parallel to grain,compression parallel to grain,compression perpendicular to grain were established on the basis of experimental studies.