超高性能混凝土铺层提升钢桥面板疲劳性能试验研究

Experimental Study of Fatigue Behaviors of Orthotropic Steel Bridge Decks Enhanced by the Ultra-High Performance Concrete Layer

摘要:

为明确超高性能混凝土（UHPC）铺层对钢桥面板疲劳性能的定量提升效果，考虑单轮和双轮两种加载模式，对正交异性钢桥面板典型的U肋?盖板?横隔板焊接节点在UHPC铺装前后的疲劳性能开展试验研究。首先基于静载试验得到焊接节点关键区域的热点应力分布，随后开展高周常幅疲劳试验，得到节点试件的疲劳裂纹萌生及扩展过程、疲劳破坏模式、刚度退化以及疲劳寿命等关键性能指标。结果表明：同等荷载作用下，钢?UHPC组合节点焊趾处热点应力值显著降低，最大降幅达58 %；与无UHPC铺层节点相比，钢?UHPC组合节点的疲劳裂纹数量减少，裂纹扩展速率和刚度退化速度得到了有效抑制，特征疲劳寿命也得到了大幅提高。国际焊接协会疲劳设计指南中的FAT 90、FAT100级S-N（应力幅?疲劳寿命）曲线可适用于UHPC铺装前后钢桥面板的疲劳寿命评估。

Abstract:

In order to validate the fatigue behavior enhancement as derived from ultra-high performance concrete（UHPC） reinforcement， typical welded details of rib-to-deck-to-floor beam （RDF） connections in orthotropic steel decks were tested by employing single- and double-wheel loading conditions. Static loading was first conducted to investigate the local stress distributions at critical areas. High-cycle constant amplitude cyclic tests were then conducted to obtain the fatigue behaviors including crack initiation and propagation， fatigue failure mode， rigidity degradation， and fatigue life of RDF connections. The results show that， by introducing the UHPC reinforcement layer， the hot spot stresses at weld toes of specimens weresignificantly reduced by up to 58 %. When compared to the specimens without the UHPC layer， the numbers of fatigue cracks of steel-UHPC composite connections were found to be reduced， and the fatigue crack growth rates and the rigidity degradation speeds were also observed to be significantly depressed during the whole process of test. The S-N curve of category FAT 90 and FAT 100 as provided in international institute of welding （IIW） fatigue design recommendations can be used to predict the fatigue lives of the steel bridge decks before and after UHPC paving.