求解桁架临界载荷的新方法

New method for solving critical load of trusess

以往求桁架结构临界载荷归结为求桁架总刚度阵的特征值，而总刚度阵中的与轴力有关的几何刚度阵，则是从各杆件始终处于直线状态，并在轴向变形中考虑横向变位影响而导出的；这样就必然导致当整体失稳时各杆件都不会发生欧拉屈曲的结果，这是不合理的．作者认为桁架失稳有可能是由杆件的局部欧拉屈曲导致成机构所造成的．由此提出一种计算桁架临界载荷的新方法，算了若干例题，并和过去的一般方法作了比较．有的两者计算结果之差竟达１８．５４倍，这就说明本方法具有理论和实际意义．

The method of characteristic value for solving the critical load of trusess is generally based on the assumption that only tensile or compressive strain exist in each member ,and when the truss is global unstable, each member keeps still the orthographic state. This is unsound. Authors think that when the truss is unstable, in general ,there must be some member finding themselves in the state of Euler-failuer. Hence a new method for finding the critical load of trusses is set , some examples are given. Authors compared them with the usual ones ,and found that sometimes the difference between results obtained by these two methods even reaches to 18. 54 times. So the method presented here is significant theoretically and practically.