The behaviour of timber columns subjected to freeze-thaw cycles under axial compression is presented in this paper.A total of forty specimens,including twenty circular timber columns and twenty square timber columns,w...The behaviour of timber columns subjected to freeze-thaw cycles under axial compression is presented in this paper.A total of forty specimens,including twenty circular timber columns and twenty square timber columns,were tested under axial compression.The failure modes,ultimate bearing capacity,ductility coefficient,load-displacement curves and load-strain curves were obtained and analyzed.The number of freeze-thaw cycles(from 0 to 80)and the specimens’height(from 225 mm to 360 mm)were considered as the main parameters.After freeze-thaw cycles,there was no obvious change on the surface of the timber columns.The test results showed that freeze-thaw cycles could reduce the ultimate bearing capacity of the timber columns,and the average reduction of the ultimate bearing capacity of the specimen reached 28%.The ductility coefficient of the square specimens subjected to freeze-thaw cycles almost remains constant compared with that of the square timber columns left untreated.While the ductility coefficient of the circular timber columns increases after freeze-thaw cycles.In addition,based on the extensive experimental analysis,a regression formula is derived to predict the ultimate bearing capacity of the timber columns after being subjected to freeze-thaw cycles,which is proved to be reasonable accurate.展开更多
By taking into account the effect of the bi-modulus for tension and compression of the fiber reinforced polymer （FRP） sheet in the reinforcement layer, a general mathematical model for the nonlinear bending of a sle...By taking into account the effect of the bi-modulus for tension and compression of the fiber reinforced polymer （FRP） sheet in the reinforcement layer, a general mathematical model for the nonlinear bending of a slender timber beam strengthened with the FRP sheet is established under the hypothesis of the large deflection deformation of the beam. Nonlinear governing equations of the second order effect of the beam bending are derived. The nonlinear stability of a simply-supported slender timber column strengthened with the FRP sheet is then investigated. An expression of the critical load of the simply-supported FRP-strengthened timber beam is obtained. The existence of postbuckling solution of the timber column is proved theoretically, and an asymptotic analytical solution of the postbuckling state in the vicinity of the critical load is obtained using the perturbation method. Parameters are studied showing that the FRP reinforcement layer has great influence on the critical load of the timber column, and has little influence on the dimensionless postbuckling state.展开更多
Eucalyptus nitens(E.nitens)has been much used for producing paper but also shows promise for structural applications.In this study,static compressive tests were undertaken to examine its suitability to be used in an i...Eucalyptus nitens(E.nitens)has been much used for producing paper but also shows promise for structural applications.In this study,static compressive tests were undertaken to examine its suitability to be used in an innovative composite column.The composite column was comprised of a rectangular steel tube with E.nitens timber infill.The nonlinear compressive behaviour of the composite column filled with E.nitens wood for both dry and wet conditions was examined.The same tests on rectangular steel tubes and bare dry and wet E.nitens samples were also undertaken as a comparison.For samples with different conditions,the ultimate capacity was evaluated and the effect of each condition on the compressive behaviour of the composite column was clarified.The steel tubes showed greater ductile behaviour,and more ductility was found in the wet samples.The steel tubes with E.nitens timber infill samples exhibited a greater linear elastic range connected with higher maximum loads,while the bare timber samples could support only lower maximum loads.The results from this research were promising for the use of rectangular steel tubes with E.nitens timber infill in structural applications.展开更多
Tenon-mortise joint is widely used in traditional timber structures around the world.This paper summarizes the results of an experimental study of the structural behavior of tenon-mortise joints made with glulam and C...Tenon-mortise joint is widely used in traditional timber structures around the world.This paper summarizes the results of an experimental study of the structural behavior of tenon-mortise joints made with glulam and CNC technology instead of traditional material and manual work.30 full-scale tenonmortise joints were manufactured and tested under monotonic loading,and the effects of dimension,shape,processing error and adhesive were evaluated.It was found that the round rectangular shaped tenon-mortise joints were comparable with traditional joints in terms of structural performance,but were time and labor saving.The variability of the proposed tenon-mortise joints was lower,which would benefit the design value.Applying adhesive between tenon and mortise increased the average stiffness by 4.3 times and average moment capacity by 27.4%,respectively.The gaps between wood members had little effect on the capacity and stiffness in monotonic bending but may influence the energy dissipation ability in cyclic bending.This study showed the feasibility of combining the traditional joinery method with modern wood products and manufacturing technology,which may promote the application of tenon-mortise joints in modern timber structures.展开更多
基金supported by the National Natural Science Foundation of China(No.51778066).
文摘The behaviour of timber columns subjected to freeze-thaw cycles under axial compression is presented in this paper.A total of forty specimens,including twenty circular timber columns and twenty square timber columns,were tested under axial compression.The failure modes,ultimate bearing capacity,ductility coefficient,load-displacement curves and load-strain curves were obtained and analyzed.The number of freeze-thaw cycles(from 0 to 80)and the specimens’height(from 225 mm to 360 mm)were considered as the main parameters.After freeze-thaw cycles,there was no obvious change on the surface of the timber columns.The test results showed that freeze-thaw cycles could reduce the ultimate bearing capacity of the timber columns,and the average reduction of the ultimate bearing capacity of the specimen reached 28%.The ductility coefficient of the square specimens subjected to freeze-thaw cycles almost remains constant compared with that of the square timber columns left untreated.While the ductility coefficient of the circular timber columns increases after freeze-thaw cycles.In addition,based on the extensive experimental analysis,a regression formula is derived to predict the ultimate bearing capacity of the timber columns after being subjected to freeze-thaw cycles,which is proved to be reasonable accurate.
基金Project supported by the National High Technology Research and Development Program(No. 2009AA032303-2)
文摘By taking into account the effect of the bi-modulus for tension and compression of the fiber reinforced polymer （FRP） sheet in the reinforcement layer, a general mathematical model for the nonlinear bending of a slender timber beam strengthened with the FRP sheet is established under the hypothesis of the large deflection deformation of the beam. Nonlinear governing equations of the second order effect of the beam bending are derived. The nonlinear stability of a simply-supported slender timber column strengthened with the FRP sheet is then investigated. An expression of the critical load of the simply-supported FRP-strengthened timber beam is obtained. The existence of postbuckling solution of the timber column is proved theoretically, and an asymptotic analytical solution of the postbuckling state in the vicinity of the critical load is obtained using the perturbation method. Parameters are studied showing that the FRP reinforcement layer has great influence on the critical load of the timber column, and has little influence on the dimensionless postbuckling state.
文摘Eucalyptus nitens(E.nitens)has been much used for producing paper but also shows promise for structural applications.In this study,static compressive tests were undertaken to examine its suitability to be used in an innovative composite column.The composite column was comprised of a rectangular steel tube with E.nitens timber infill.The nonlinear compressive behaviour of the composite column filled with E.nitens wood for both dry and wet conditions was examined.The same tests on rectangular steel tubes and bare dry and wet E.nitens samples were also undertaken as a comparison.For samples with different conditions,the ultimate capacity was evaluated and the effect of each condition on the compressive behaviour of the composite column was clarified.The steel tubes showed greater ductile behaviour,and more ductility was found in the wet samples.The steel tubes with E.nitens timber infill samples exhibited a greater linear elastic range connected with higher maximum loads,while the bare timber samples could support only lower maximum loads.The results from this research were promising for the use of rectangular steel tubes with E.nitens timber infill in structural applications.
文摘Tenon-mortise joint is widely used in traditional timber structures around the world.This paper summarizes the results of an experimental study of the structural behavior of tenon-mortise joints made with glulam and CNC technology instead of traditional material and manual work.30 full-scale tenonmortise joints were manufactured and tested under monotonic loading,and the effects of dimension,shape,processing error and adhesive were evaluated.It was found that the round rectangular shaped tenon-mortise joints were comparable with traditional joints in terms of structural performance,but were time and labor saving.The variability of the proposed tenon-mortise joints was lower,which would benefit the design value.Applying adhesive between tenon and mortise increased the average stiffness by 4.3 times and average moment capacity by 27.4%,respectively.The gaps between wood members had little effect on the capacity and stiffness in monotonic bending but may influence the energy dissipation ability in cyclic bending.This study showed the feasibility of combining the traditional joinery method with modern wood products and manufacturing technology,which may promote the application of tenon-mortise joints in modern timber structures.
