Experimental Study On Compressive Properties Of Side-pressure Laminated Bamboo Columns

In recent years,with the rapid development of urbanization and modernization,the environmental pollution caused by the construction industry has become increasingly serious,and the development of green and new building structural materials has become an inevitable trend.Pressure laminated bamboo is a kind of profile with a certain size,which is made by gluing bamboo slices with adhesives.Side-pressure laminated bamboo has good mechanical properties,which provides a certain possibility for its use as building structural materials.In order to investigate the mechanical properties of side-pressure laminated bamboo columns,3 parts were carried out in this paper:18 specimens with different slenderness ratios in 6 groups were subjected to axial compression tests,the failure modes of different slenderness ratios were discussed,and the relationships among bearing capacity,strain,lateral displacement,axial displacement and slenderness ratio were analyzed.Two groups of 6 specimens with eccentricity distances of 20mm and different slenderness ratios were tested under eccentric compression,and their failure modes were discussed;The relationship between the ultimate bearing capacity and the lateral displacement of the elastoplastic bar is deduced according to the stability theory of the compression bar.the following research results were obtained:(1)When the axis is under compression,the mechanical process of the side-pressure laminated bamboo column under lateral compression has gone through the stages of elasticity,elastoplastic and failure.During the failure,the specimen has obvious transverse deformation,so the material failure has obvious ductility properties.With the increase of slender-to-slenderratio,the failure mode of specimens under axial compression changes from material strength failure to buckling failure.(2)When the specimen is under eccentric compression,the stress process of the specimen is similar to that of the axial compression.When the specimen is damaged,the rotation angle of the supports at both ends of the specimen and the transverse deformation of the specimen are both large,and the tensile side of the specimen is pulled off due to the excessive transverse deformation.(3)According to the theory of large deflection analysis of axial compression specimens after buckling loads and lateral deformation,the relationship between the theoretical calculation value and the actual measured values were analysed.The results show that the relative error is less than 1%.By comparing and analyzing the test results with the calculation results in the various current specifications,a formula for calculating the ultimate bearing capacity of the axial compression column of side-pressed laminated bamboo columns is put forward,and the calculated values are in good agreement with the experimental values.(4)The relationship between buckling load and lateral deformation of eccentric compression column was analyzed by Jezek approximate analytical method.It was concluded that the two groups of eccentric compression specimens in this paper were all small eccentric compression specimens.The lateral deflection curves of specimens under all levels of loads are close to sinusoidal half-wave curves.The formulas for calculating the ultimate bearing capacity and ultimate lateral displacement under eccentric compression are deduced,and the theoretical value and measured value close,the relative error less than 8%.It is indicated that the Jezek approximate analytic method is useful for the calculation of the bearing capacity and lateral displacement of the specimen under eccentric compression.