For a truss with more than one redundant bar, more than one release will be required to obtain the primaryframe .
对于有一个以上多余杆的桁架要得到基本体系,就要放松一个以上的约束。
3
Considering the restraining moment of the secondary beam, the paper deduces formulas for calculating torsional moment of edge beam of frame. Primary factors of affecting torsional moment are analyzed.