地铁车站的基坑围护结构中一般采用预应力钢支撑作为支撑体系。本文试图以变分法为工具求出钢支撑在承受压弯状态下的挠度公式,最后以钢结构所应满足的整体失稳规范要求得到钢支撑的极限长度Lmax不等式,并建立挠度与各类参数的图,备土木工程人员参考。 Prestressed steel support is generally used as the supporting system in the foundation pit retaining structure of metro station. In this paper, we try to find out the deflection formula of steel brace under the condition of bending under the condition of variational method. Finally, the limit length Lmax inequality of steel brace is obtained by the global instability criterion that steel structure should meet, Parameters of the map, prepare civil engineering staff reference.