| Compared with other building materials,wood has a unique advantage in environmental protection as a building material.Meanwhile,Wood as a renewable resource,in line with sustainable development strategies.Nowadays,when green buildings and fabricated buildings are promoted in China,the development of wooden structure architecture has ushered in a new opportunity.With the improvement of production technology and advancement of technology,many engineering wood products have appeared one after another.and the advent of these wood products has overcome the defects of wood itself and improved the tensile and compressive properties of wood as well.Cross Laminated Timber(CLT)slabs are a new type of engineering wood product.The mechanical properties of CLT slabs at ambient temperature and high temperature are different from those of other engineering wood products due to the use of orthogonal composite.In recent years,the occurrence of building fire in China shows an upward trend,and the occurrence of fire will cause property damage and casualties.Due to the flammability of wood itself,the fire resistance of wood is different from that of concrete and steel.At the same time,the CLT slab are mainly used in multi-storey and multi-storey wood structures,and its fire resistance will be a key issue that cannot be ignored.Foreign scholars have carried out corresponding research on the fire resistance of CLT slabs,but the domestic research on the fire resistance of CLT slabs is relatively few.Therefore,it is necessary to carry out the corresponding research.Given this situation,this dissertation carries out the fire resistance experimental study of CLT wall with CLT slabs made from Larix kaempferi Carr.The main conclusions are as follows:(1)The material properties experiments at the component level were carried out,including interlaminar shear test,rolling shear test and compression test.The interlaminar shear strength,rolling shear modulus,rolling shear strength,compressive modulus and compressive strength of CLT slabs were obtained.(2)The ultimate bearing capacity test of four CLT walls at ambient temperature and the fire resistance test of four CLT walls under the standard fire were carried out.The effect of the composition of laminate and the laod ratio on the fire resistance were studied.The results show that The ultimate bearing capacity of three-layer CLT wall is higher than that of five-layer CLT wall,the failure mode of the CLT wall at ambient temperature is mainly buckling failure,Meanwhile,the knots on the layer of the tension zone will affect the failure mode of the CLT wall.The fire resistance of the CLT wall decreases with the increase of the load holding ratio of the specimen.And the fire resistance of the three-layer wall is higher than that of three-layer CLT wall when the load ratio is the same.(3)The load ratio and the orthogonal composite has little influence on the inner temperature of the CLT wall,the gap between laminates have certain influence on the distribution of the temperature field of the CLT wall,and affect the charring rate of the wall,and then affect the fire resistance of the CLT wall.(4)The CLT wall made of glue which is not resistant to high temperature will not fall off in the experiment.The reason for the fall off is not only related to the type of glue,but also to the actual stress state of the specimen.(5)Based on the finite element software Abaqus,by using the indirect coupling method,obtained the displacement-load curve and stress distribution of the CLT wall at the ambient temperature,and the temperature field,displacement-time curve and stress distribution of the wall at standard fire,which were in good agreement with the experimental results.(6)Combined with the foreign CLT design manual and based on the "residual section method",considering the reduction of compressive strength of CLT wall,a numerical calculation method suitable for zero strength layer of CLT wall was proposed,obtained the theoretical calculation formula for the fire resistance of CLT wall. |
