毛竹压杆屈曲系数公式研究

Research on the formula for buckling coefficient of Moso bamboo column

为获得四川地区毛竹压杆更精确的屈曲系数公式,通过试验方法测定四川地区毛竹的顺纹抗压强度以及31根长细比分布较为均匀的竹压杆临界荷载,并对国内外现有的9个竹压杆屈曲系数公式进行研究。结果表明:此批毛竹顺纹抗压强度平均值约为51MPa;竹压杆的破坏是由于局部鼓曲变形和整体弯曲变形叠加,最终竹压杆管壁超过横纹抗拉强度极限值进而纵向开裂;现有竹压杆屈曲系数公式所得到的临界荷载计算值之间有所差异,与文中试验实测临界荷载值也有不同程度的差异。最后采用具有较好拟合优度的Ylinen方法,基于文中试验数据拟合提出适用于四川地区的毛竹压杆屈曲系数公式。

In order to obtain a more accurate buckling coefficient formula for the Moso bamboo column in Sichuan area,the compressive strength parallel to the grain and the critical load of 31 bamboo columns with a relatively uniform distribution of slenderness ratio were measured by the experiment,and 9 formulas for the buckling coefficient of bamboo column at home and abroad were studied.The results show that the average compressive strength parallel to the grain of this batch of bamboo is about 51 MPa.The failure of the bamboo columns is due to the superposition of local bulging and overall flexural deformation,which eventually causes the bamboo column tube wall to exceed the limit value of the tensile strength perpendicular to the grain and crack longitudinally.The bamboo columns are collapsed due to the interaction of the elastic compression and the longitudinal plastic crack induced by the local buckling behavior of the bamboo tube.The larger the slenderness ratio,the more obvious the lateral deflection,and the damage degree of local plastic cracking in the bamboo column with larger slenderness is more evident.The differences in the critical loads calculated by the existing formulae for the buckling coefficient of bamboo column can be observed,and these predicted critical loads differ from the measured critical load to some degree.Finally,using the Ylinen method with good degree of fitting,a formula for buckling coefficient of bamboo column applicable to Sichuan is proposed based on the test data.