针对目前平板钢闸门结构形式存在的内力分布不均，主梁跨中弯矩大的问题,根据超静定结构承载力高于静定结构的原理，提出了弹性固定支座平板钢闸门主梁新型结构形式。以跨中截面与支座截面等安全度为原则，确定弹性固定支座截面合理转角；根据结构可靠度理论评价该结构主梁的可靠度指标，并与现行结构形式主梁的可靠度进行比较。结果表明：该新型结构可以在主梁截面不变情况下提高可靠度指标 1.44 ，在可靠度指标不变情况下减少材料30%，可靠度沿跨长的分布均匀，为一种经济合理、安全可靠的结构形式。

To solve the problems in current plane gate structures such as uneven distribution of internal forces and large bending moment in main girder mid-span, a new main girder structure of plane steel gate fixed by elastic bearing is proposed according to the theory that the bearing capacity of statically indeterminate structure is higher than that of statically determinate structure. Taking the equal safety degree between mid-span section and bearing section as a principle, the reasonable corner of the elastic fixed bearing section is determined ； and based on structural reliability theory, the reliability index of the main girder is evaluated and is compared with the reliability of existing structure girder. The results show that the new structure can improve the reliability index by 1.44 under a constant main beam section;or reduce the material consumption by 30% under a constant reliability index ； and the distribution of reliability along the span length is uniform. Therefore, it is an economical, safe and reliable structure.