| Cross Laminated Timber(CLT)is a new kind of prefabricated engineered wood product consisting of at least three layers of lumber lamination or structural composite lumber,where the adjacent layers are cross-oriented and bonded with structural adhesive,and this kind of solid wood element can be used for wall,floor and roof systems.Because of its excellent mechanical properties,CLT has a potential in developing multi-and highrise buildings,and has gained extensive attention.Due to the very low rolling shear modulus,the shear deformation has a significant influence on the stability capacity.However,at present,the research on the stability of CLT members in axial compression is insufficient at home and abroad,and there is no calculation method for the stability coefficient of CLT axial compression members in GB 50005—2017.In this paper,four kinds of calculation methods for effective bending stiffness were expounded—mechanical jointed beam method,composite method,shear analogy method,and simplified method,then the characteristics of each calculation method and the differences of the calculation results were compared and analyzed.What’s more,the influence of the number of layers and the span to depth ratio on the calculation results of effective bending stiffness was discussed and evaluated.Buckling tests were carried out on 3-ply CLT members in axial compression with different slenderness ratios.There were four specimens in each group to obtain the stability capacity and load-displacement curves.After the buckling tests,two specimens were cut at each end of the specimens which were used to obtain the compressive bearing capacity of each specimen.Then the stability coefficient of each specimen can be obtained.The principles and differences of calculation methods for CLT stability coefficient in the design codes of various countries were studied and compared.Considering the characteristics of CLT products,new equations for calculation of the stability coefficient applicable to CLT members,which was based on the equation used in GB 50005—2017.The equation of stability coefficient applied to CLT members in NDSWC-2018 was modified to conform to the principle of Chinese code for design of timber structure.The calculation result of the modified stability coefficient equation was taken as the source data,which was then used to determine the factors in the newly proposed equations through regression.The correctness of the equations was confirmed by comparing with the experimental results. |
