正交异性钢桥面板顶板竖向加劲肋焊接接头疲劳性能试验研究

Study on fatigue performance of welded joints for out-of-plane gusset in orthotropic steel bridge decks

正交异性钢桥面板的疲劳问题是目前研究的主要热点之一。该文针对国内钢桥面板顶板竖向加劲肋焊接接头的构造细节,通过振动型疲劳试验机开展了18个试件的弯曲疲劳试验,研究了普通角焊缝和熔透角焊缝在不同加载应力幅下的疲劳性能,分析了焊接接头的应力集中系数,并与有限元分析结果进行了对比,得到了普通角焊缝和熔透角焊缝焊接接头疲劳寿命大小;同时采用BS5400、JSSC、Eurocode 3以及我国钢结构设计规范(GB 50017—2003)规定的S-N曲线对试验结果的疲劳强度进行了评定。研究表明:钢桥面板竖向加劲肋焊接接头熔透角焊缝的疲劳性能总体上优于普通角焊缝,对我国钢桥面板竖向加劲肋焊接接头的开裂前的疲劳性能建议采用BS5400-F2的S-N曲线(35MPa)进行设计和评价;并且两者焊接接头的应力集中系数约为2.4左右,其中熔透角焊缝受到焊接工艺的影响其应力集中系数较大,须在焊接后对其进行焊趾表面处理,以进一步提高疲劳性能。

Fatigue is one of the main problems in orthotropic steel bridge decks. In this study, the fatigue tests were carried out to study the fatigue performance of normal and full penetration fillet welds at different stress amplitudes. 18 specimens were tested for their flexural fatigue performance by using the fatigue testing machine. The stress concentration factor （SCF） was analyzed and compared with the FEM results. Furthermore, the S-N curves of BS5400, JSSC, Eurocode 3 and GB 50017-2003 were used to evaluate the fatigue strength of specimens. Research results show that the full penetration fillet weld has a better fatigue performance than normal one. It is recommended that the S-N curve of BS5400-F2 code （35MPa） shall be utilized to evaluate and design the fatigue performance of welded joints of out-of- plane gusset before cracking in China. The SCF values for two types of fillet welds is about 2.4, but the SCF value of full penetration fillet weld is slightly larger due to its welding technology. As a result, the surface of its weld toe shall be treated after the welding to further improve its fatigue performance.