既有工业厂房钢吊车梁疲劳性能预后分析

Fatigue prognosis analysis on existing steel industrial crane runway girders

摘要:

为更好地理解工业厂房钢结构的疲劳性能衰退机理,有效预防结构发生脆性断裂,发展了面向既有工业厂房钢结构的疲劳性能预后分析方法.基于跨尺度界面功平衡原理建立了工业厂房钢结构疲劳损伤多尺度模型,量化了结构既有缺陷引起的损伤,研究了工业厂房钢结构关键构件——钢吊车梁的疲劳损伤演化和复合型疲劳裂纹扩展过程.疲劳预后分析结果表明:钢吊车梁焊缝区域的损伤在初始阶段增长较为缓慢,后期急剧加快,论证了工程中常用的线性Miner损伤准则会导致评估结果过于保守；变截面钢吊车梁的插板与封板连接处的焊缝区域最容易发生疲劳失效,本次研究的吊车梁裂纹深度a超过5 mm后,裂纹迅速扩展,应对其进行加固处理；主要易损部位的裂纹对其他易损部位的疲劳性能影响较大.

Abstract:

To better reveal the inner fatigue deterioration mechanism of steel industrial plants and effectively protect the plants from brittle fractures, a fatigue prognosis analysis method was proposed. Multi-scale fatigue damage models were established based on the power balance principle at the cross-scale interface. The damage of the structures caused by existing defects was quantified. Fatigue damage evolution and mixed mode crack propagation of the vulnerable positions were analyzed. Fatigue prognosis results illustrated that the fatigue damage of the steel crane runway girder evolved slowly at the initial phase and accelerated rapidly at the final phase, which proved that the assessment results based on Miner’s law are too conservative. Fatigue failure more likely occurred at the weld joint between the spile and the end sealing plate of the steel crane runway girder. The studied fatigue crack grew rapidly when the length a reached 5 mm, in which some actions should be taken. The crack in the serious position had great influence on the fatigue performance of other vulnerable parts.