Eucalyptus is a major fast-grown species in South China,which has the potential for producing structural wood products such as cross-laminated timber(CLT).Aspect ratio(board width vs.board thickness)of eucalyptus lumb...Eucalyptus is a major fast-grown species in South China,which has the potential for producing structural wood products such as cross-laminated timber(CLT).Aspect ratio(board width vs.board thickness)of eucalyptus lumbers is small due to the small diameter of fast-grown eucalyptus wood.To evaluate its rolling shear modulus and strength for potential CLT applications,three-layer hybrid CLT shear block specimens with different aspect ratios(2,4,6),were tested by planar shear test method.Digital image correlation(DIC)was employed to measure the rolling shear strain distribution and development during the planar shear tests.The mean values of rolling shear modulus and strength of eucalyptus lamination were 260.3%and 88.2%higher than those of SPF(Spruce-pine-fir)lamination with the same aspect ratio of 4,respectively.The rolling shear properties of eucalyptus laminations increased as the aspect ratio increased.Aspect ratio had a significant influence on rolling shear modulus compared to rolling shear strength.The high shear strain regions were primarily found around the gaps between segments of cross layer.The quantity of high shear strain regions increased as the aspect ratio of lamination decreased.Other high shear strain regions also occurred around the pith and along the glue line.The sudden failure of specimen occurred in the high strain region.In conclusion,the rolling shear strength and modulus of fast-grown eucalyptus laminations exceed the respective characteristic values for softwoods in the current standard by roughly factors of 3 and 8,indicating great potential for fast-grown eucalyptus wood cross-layers in CLT.展开更多
The out-of-plane shear properties of cross-laminated timber(CLT)substantially influence the overall mechanical properties of CLT.Various testing methods and theories related to these properties have recently been deve...The out-of-plane shear properties of cross-laminated timber(CLT)substantially influence the overall mechanical properties of CLT.Various testing methods and theories related to these properties have recently been developed.The effects of the number of layers(three and five layers)and testing method(short-span three-and four-point bending tests)on the out-of-plane shear properties of CLT were evaluated.The out-of-plane shear strength values were calculated based on different theories for comparison.The failure mode in the short-span four-point bending(FPB)method was mainly the rolling shear(RS)failure in the cross layers,indicating that the FPB method was appropriate to evaluate the RS strength of CLT.The out-of-plane shear capacity obtained using the three-point bending(TPB)method was higher than that tested by the FPB method.The testing methods significantly influenced the out-of-plane shear capacity of the three-layer specimens but not that of the five-layer specimens.With an increase in the number of layers,the out-of-plane shear strength of the specimens decreased by 24%.A linear correlation was found among the shear strength values obtained from different theories.展开更多
基金the National Natural Science Foundation of China(Grant No.31570559 and No.51808293)Natural Science Foundation of Jiangsu Province,China(Grant No.BK20180778).
文摘Eucalyptus is a major fast-grown species in South China,which has the potential for producing structural wood products such as cross-laminated timber(CLT).Aspect ratio(board width vs.board thickness)of eucalyptus lumbers is small due to the small diameter of fast-grown eucalyptus wood.To evaluate its rolling shear modulus and strength for potential CLT applications,three-layer hybrid CLT shear block specimens with different aspect ratios(2,4,6),were tested by planar shear test method.Digital image correlation(DIC)was employed to measure the rolling shear strain distribution and development during the planar shear tests.The mean values of rolling shear modulus and strength of eucalyptus lamination were 260.3%and 88.2%higher than those of SPF(Spruce-pine-fir)lamination with the same aspect ratio of 4,respectively.The rolling shear properties of eucalyptus laminations increased as the aspect ratio increased.Aspect ratio had a significant influence on rolling shear modulus compared to rolling shear strength.The high shear strain regions were primarily found around the gaps between segments of cross layer.The quantity of high shear strain regions increased as the aspect ratio of lamination decreased.Other high shear strain regions also occurred around the pith and along the glue line.The sudden failure of specimen occurred in the high strain region.In conclusion,the rolling shear strength and modulus of fast-grown eucalyptus laminations exceed the respective characteristic values for softwoods in the current standard by roughly factors of 3 and 8,indicating great potential for fast-grown eucalyptus wood cross-layers in CLT.
基金by National Natural Science Foundation of China(Grant No.31570559)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The out-of-plane shear properties of cross-laminated timber(CLT)substantially influence the overall mechanical properties of CLT.Various testing methods and theories related to these properties have recently been developed.The effects of the number of layers(three and five layers)and testing method(short-span three-and four-point bending tests)on the out-of-plane shear properties of CLT were evaluated.The out-of-plane shear strength values were calculated based on different theories for comparison.The failure mode in the short-span four-point bending(FPB)method was mainly the rolling shear(RS)failure in the cross layers,indicating that the FPB method was appropriate to evaluate the RS strength of CLT.The out-of-plane shear capacity obtained using the three-point bending(TPB)method was higher than that tested by the FPB method.The testing methods significantly influenced the out-of-plane shear capacity of the three-layer specimens but not that of the five-layer specimens.With an increase in the number of layers,the out-of-plane shear strength of the specimens decreased by 24%.A linear correlation was found among the shear strength values obtained from different theories.
