Fatigue performance of cracked rib-deck welded joint retrofitted by ICR technique

To evaluate the retrofit effect by ICR technique (a new technique developed in recent years), relative tests were carried out with two cracked rib-deck specimens. The fatigue performance, including crack propagation rate, remaining fatigue life, and stress variation was analyzed. An improvement was observed through the test results after the cracked specimen retrofitted. Crack propagation in the treated specimen was restrained by the closed surface and residual compressive stress, and the crack propagation rate was reduced significantly. Stress at the welded joint and the crack tip was redistributed after ICR treatment. An increasing has been found near the weld toe, and reduction is occurred at the crack tip, which matches FEM results. This stress variation might contribute to a delay in subsequent crack propagation.     

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

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。     

基于生产动态资料的凝析气藏流体分布及潜力再认识——以渤海BZ油气田太古宇潜山为例

针对渤海BZ油气田太古宇潜山凝析气藏投产后生产动态与初始静态认识存在较大差异的问题,综合利用钻井、测井、取样及DST等资料,结合生产动态资料,对该气藏类型、流体分布及资源潜力进行了再认识.结果 表明:研究区太古宇潜山凝析气藏原油产出经历了凝析油—凝析油+黑油—黑油的过程,为一个带黑油油环的构造层状凝析气藏,而非勘探评价...     

Fatigue Strength and Root-Deck Crack Propagation for U-Rib to Deck Welded Joint in Steel Box Girder

Fatigue tests and numerical analysis were carried out to evaluate the fatigue performance at the U-rib to deck welded joint in steel box girder. Twenty specimens were tested corresponding to different penetration rates (80 and 100%) under fatigue bending load, and the fatigue strength was investigated based on hot spot stress (HSS) method. The detailed stress distribution at U-rib to deck welded joint was analyzed by the finite element method, as well as the stress intensity factor of weld root. The test results show that the specimens with fully penetration rate have longer crack propagation life due to the welding geometry, resulting in higher fatigue failure strength. The classification of FAT-90 is reasonable for evaluating fatigue strength by HSS method. The penetration rate has effect on crack propagation angle near the surface, and the 1-mm stress below weld toe and root approves to be more suitable for fatigue stress assessment, because of its high sensitivity to weld geometry than HSS.