昆山市震川西路水泥混凝土路面改建设计关键技术

随着交通量的增加和路面状况的恶化，大量的水泥混凝土路面都面临着翻修改建的任务，加铺沥青混凝土罩面是其中最常用的方法之一。为确定经济合理的加铺结构层，保证路面结构强度，延长道路使用寿命，防治反射裂缝是其关键技术。通过介绍震川西路改建的设计及施工方案，为类似工程提供参考。     

轨道车辆座椅裂纹分析及改善措施仿真研究

文章介绍了轨道车辆常见座椅分类及其布置,针对某型轨道车辆统计了运行中座椅裂纹分布情况及位置信息,分析了座椅裂纹产生原因,提出了改善座椅裂纹的措施,并通过相应计算及仿真分析验证了座椅裂纹改善措施的可行性。     

Crack growth direction effects on corrosion-fatigue behaviour of offshore wind turbine steel weldments

In this study corrosion-fatigue tests have been conducted on fracture mechanics specimens extracted from an S355 G10+M structural steel welded plate. The tests have been performed on compact tension specimens with the crack tip located in the heat affected zone. The corrosion-fatigue test results from this study have been compared with the data available on the base metal as well as air tests on the same material. Moreover, the obtained results have been compared with the corrosion-fatigue data available in the literature on a wide range of steels and also the fatigue trends for welded joints in free-corrosion condition recommended in the BS7910 Standard. The effect of the specimen orientation, with respect to the weld region, is also examined in this study and it has been found that higher corrosion-fatigue crack growth rates are generally observed in the tests with 0° orientation. The results have also shown that the corrosive environment has significant effects on the fatigue crack growth acceleration at the beginning of the tests; however, as the crack propagates, the environmental damage effect on crack growth behaviour becomes less pronounced. The results presented in this study are discussed in terms of improvement in the structural integrity assessment of offshore wind turbine monopiles.     

The effect of weld residual stress on fracture toughness at the intersection of two welding lines of offshore tubular structure

Due to the spatial complexity and fabrication characteristics of offshore platforms, it is inevitable to encounter overlaps or proximity of weld lines in tubular joints. Several international standards such as American Petroleum Institute (API), American Welding Society (AWS), and American Institute of Steel Construction (AISC) regulate the minimum distance between primary weld beads; however, any logical and detailed background of this limitation has not been presented. For a non-compliant weld joint where the regulation is not met, fracture toughness calculation is a typical index to verify the structural integrity.This research consists of two parts. First, weld residual stress distributions are calculated by a 3D thermo-mechanical nonlinear Finite Element Analysis. Two crossing welds, a T-weld crossing on a butt weld, are simulated in one model. A separate tee and a butt welding simulations are also performed for a comparative purpose. Second, SIFs and J-integral values are calculated at the surface and deepest crack tip locations for four different types of semi-elliptical surface cracks. Four cracks are embedded into the weld model and the residual stress distribution from the 3D thermo-mechanical FEA are mapped to a 3D FE crack model as initial conditions. An additional axial tensile load is also imposed. SIF values are compared with those using the weighting function method for the butt weld model subject to three load cases, i.e., tensile stress only, weld residual stress only, and both of them. From the simulation, a tubular joint containing a chord girth weld intersected with weld beads of brace is found to show lower the SIF values than that having only a girth weld on chord.     

施工及环境因素诱发污水处理池差异沉降及渗漏风险

针对地基变形特征及其引发的大型污水处理池混凝土结构破裂渗漏风险，研究人工降水、开挖与桩基加固、滨海潮汐地下水渗透等条件下的地基变形特性，并建立地基变形基本方程及多因素综合影响下的统一函数表达式。结合上海白龙港污水处理厂工程，分析了工程区域施工及环境因素可能产生的地基变形及其对结构受力的不良影响。结果表明：i）地基变形曲率对结构受力产生直接影响，曲率半径越小，结构的附加应力越大、致裂风险越高；ii）结构高度越大，对地基弯曲变形的反应越敏感；iii）结构抗弯刚度突变处，应力集中程度高、局部应力超限风险增大。     

沙漠戈壁公路沥青路面裂缝成因分析及处治措施

我国沙漠戈壁公路在建成不久后路面病害就显现出来,特别是裂缝类病害,尤为严重.以G215国道柳园至敦煌公路沥青路面裂缝为例,横向裂缝、纵向裂缝广泛分布.调查分析裂缝的特征,分析出沙漠戈壁的极端气候,路面材料选择不当,盐渍土对路基、路面的侵蚀及过往施工质量问题是沥青路面裂缝病害的成因.根据裂缝形成的原因,提出沙漠戈壁公路沥青路面裂缝的处治措施,可为同类工程提供经验.     

沥青路面常见的病害及其预防措施

介绍沥青路面中常见的一些病害,重点阐述沥青路面出现裂缝的原因,并提出相应的预防措施,可供沥青路面设计和施工人员参考。     

框架结构钢筋混凝土面板裂缝分析与防治

对重庆果园港区码头现浇钢筋混凝土面板裂缝进行理论分析，找出产生裂缝的原因，并针对性地采取措施。这些措施包括：提高混凝土本身抗拉强度；采用混凝土后浇带方式在施工期间解除束缚面板混凝土的约束；通过对混凝土原材料、配合比的优化和采取施工措施来减少混凝土的自生收缩、塑性收缩、干缩及温度变化和内外温差引起的收缩，从而大大降低混凝土的收缩应力。     

东南沿海地区全季节预制箱梁混凝土配合比设计

针对70 m预制箱梁混凝土早期抗压强度及耐久性的需求，通过调整胶凝材料的用量以及掺合料的掺配比例，进行多次试配、试验，配制出满足东南沿海地区不同季节气候条件下箱梁混凝土施工工艺需求的海工耐久混凝土配合比。     

钢筋混凝土桥梁裂缝成因及控制技术初探

在现代道路桥梁建设中,钢筋混凝土已经占据重要的部分.而裂缝在混凝土结构中普遍存在,对工程建筑造成巨大的影响.文章分析了混凝土裂缝的成因,并对控制技术进行探讨.