深圳至中山跨江通道钢桥面板结构疲劳试验研究

正交异性钢桥面板的疲劳开裂问题是制约桥梁工程可持续发展的关键难题,亟需发展具有高疲劳抗力特性的正交异性钢桥面板结构。依托深圳至中山跨江通道项目,在钢桥面板结构中同时引入纵肋与顶板新型双面焊构造细节和纵肋与横隔板新型交叉构造细节两类构造细节,设计9个足尺节段模型,通过模型试验确定了纵肋与顶板传统单面焊构造细节和新型双面焊构造细节、纵肋与横隔板传统交叉构造细节和新型交叉构造细节的疲劳开裂模式和实际疲劳抗力;采用扫描电子显微镜(SEM)确定了不同制造工艺条件下纵肋与顶板焊接细节的初始制造缺陷尺度;采用等效结构应力法确定了两类细节各疲劳开裂模式的疲劳抗力。研究结果表明:纵肋与顶板传统单面焊构造细节的疲劳裂纹起裂于顶板焊根并沿顶板厚度方向扩展,其疲劳抗力为95.1～98.7MPa,新型双面焊构造细节的疲劳裂纹起裂于顶板内侧焊趾并沿顶板厚度方向扩展,其疲劳抗力为108.5～123.2MPa,且在相同加载条件下,双面埋弧焊构造细节的疲劳抗力高于双面焊气体保护焊构造细节的疲劳抗力;传统单面焊构造细节焊根的初始制造缺陷尺度显著大于新型双面焊构造细节焊趾的初始制造缺陷尺度,且双面埋弧焊的初始制造缺陷尺度小...

Fatigue model tests of orthotropic steel bridge deck of Shenzhen-Zhongshan Link

Fatigue cracking of orthotropic steel bridge deck (OSD) is a key problem restricting the sustainable development of bridge engineering. Based on the Shenzhen-Zhongshan link project, the rib-to-deck innovative both-side welded joint and the rib-to-diaphragm innovative welded joint were introduced into the bridge deck, and nine full-scale segment models were designed. Furthermore, the fatigue cracking patterns and fatigue resistance of the rib-to-deck welded joint and the rib-to-diaphragm welded joint were determined by model tests. The initial microcrack scales of the rib-to-deck welded joints were studied by Scanning Electron Microscope (SEM). An equivalent structural stress method was employed to determine fatigue cracking patterns and fatigue resistance of the two details. The results showed that the fatigue cracks of one-side welded joint initiated from the weld root and then propagated along the thickness direction of deck, and its fatigue resistance was 95.1MPa to 98.7MPa. The fatigue cracks of the innovative both-side welded joint initiated from the inside weld toe and propagated along the thickness direction of deck, and its fatigue resistance was 108.5MPa to 123.2MPa. Under the same loading conditions, the fatigue resistance of the both side submerged arc welding structural details was higher than that of the both-side gas shielded welding structural details. It was found that the initial microcrack size at the weld root of one-side welded joint was noticeably larger than that at weld toe of both-sidewelded joint, and the initial micro-crack size of both-side submerged arc welding was smaller than that of the bothside gas shielded welding. The fatigue cracks of the traditional rib-to-diaphragm welded joint initiated from the weld toe of rib-to-diaphragm welded joint and then extended along the rib, whereas the fatigue cracks of the innovative welded joint initiated from the weld toe of the rib bottom and then propagated along the bottom plate. The crack initiation times were basically the same for the two structural details, but the propagation rate of the traditional one was remarkably higher than that of the innovative one. Test results of fatigue cracking modes of the two details basically varied between ±2σ of the master S-N curve.