机动法求刚架极限荷载时的超静定问题

Statically indeterminate problems in calculating the ultimate load of frames

用机动法求刚架的极限荷载时 ,常用基本机构迭加法设定破坏机构 .然而 ,当所设机构的塑性铰数<n +1 (n为原结构的超静定次数 ) ,验算屈服条件时内力计算必将遇到超静定问题 ,此种情况的内力如何计算 ,现行《结构力学》教材中未提及或未充分论述 ;已有方法不具有一般性 ,求出的内力不一定是完全解的极限荷载对应的真实内力 .着重讨论了刚架极限荷载计算中的超静定问题的处理方法 ,给出了既能验算屈服条件 。

When using the upper bound theorem to solve the ultimate load of frames, it is usually to set the plastic mechanism by combined mechanism method of elementary mechanisms. However, if the number of plastic hinges of the plastic mechanism set is less than n+1(n is the degree of redundancy of original structure), the statically indeterminate problems surely occur in calculating the internal forces for checking yield condition. In this paper a method is proposed which can not only give the true internal forces corresponding to the complete solution but also can check the yield condition.