变截面吊车梁圆弧式和直角式突变支座的受力性能分析

Mechanical Analysis of Arc-Shape and Right-Angle Supports of Crane Girders with Variable Cross Sections

采用圆弧式突变支座的变截面吊车梁在实际工程中出现了普遍性的疲劳裂缝,而直角式突变支座则未发现这类问题。现针对这两类变截面的吊车梁进行有限元分析,比较和探讨其截面突变处的局部应力状态和力学性能。分析结果表明,圆弧式突变支座翼缘与腹板连接处可形成两个方向较大的主应力,应力集中严重,在动荷载作用下易成为疲劳破坏的薄弱点,而直角式突变的梁中应力集中情况得到了较大的缓和。因此,在工程设计中,尤其是涉及动力荷载时,变截面梁支座构造形式不宜采用圆弧式,直角式应是一种良好的替代。

Prevailing fatigue cracking has been witnessed in practical variable cross section crane girders with the arc-shape support detail, while not in those with the right-angle support detail. Finite element （FE） analyses were performed on variable cross section crane girders with the two types of support details to compare and investigate the local stress state and mechanical performance. FE analysis results indicated that principle stresses in the two directions are considerably high at the connecting area between the flange and web of the arc-shape support and stress concentration is significant, so that fatigue failure may occur at this point under dynamic loading, while for the right-angle support stress concentration is mitigated. As a result, it is recommended to adopt the right-angle support to replace the arc-shape detail for practical engineering designs, especially in dynamic loading conditions.