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针对中欧混凝土结构设计规范的异同点,在混凝土强度等级、保护层厚度、环境暴露等级等方面进行对比论述,并分析欧洲规范的承载能力计算、裂缝开展宽度计算原理。以实际项目为例,对受弯构件的承载能力、配筋和裂缝宽度等进行定性分析,得出同等条件下中国规范较欧洲规范的裂缝计算值更大但裂缝控制更为严格等结论,为海外项目结构设计提供参考。 相似文献
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针对水运工程混凝土受弯构件采用高强钢筋后裂缝宽度计算的问题,通过分析国内各专业混凝土规范的裂缝宽度计算公式,得出水运工程规范裂缝宽度的计算结果最大。在设计中虽然采用高强钢筋,但钢筋用量基本不变,限制其强度的发挥,不利于高强钢筋的推广,根据其他学者的同类统计公式,提出适用于水运工程的裂缝宽度修正公式,并经对比验证。结果表明,本文公式与其他公式符合性较好,可供规范修订时参考。 相似文献
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航迹带宽度是航道规划、设计的重要参数,一直是航道宽度计算的难点。针对现行规范航迹带宽度计算系数取值困难的问题,基于船舶操纵模拟器,通过采集模拟试验仿真数据,采用将船舶航迹带宽度分为航线偏移量和船舶本身占用空间来直接计算航迹带宽度的方法。结合台州湾大桥区航道,仿真计算了典型风、流工况的航迹带宽度,仿真结果与现行规范计算结果基本一致。表明该方法可行,且具有很好的实用价值。 相似文献
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以大型通用有限元计算软件ANSYS为平台,建立了荷载作用下钢筋混凝土构件裂缝宽度的一种计算方法。采用ANSYS中的Solid 65单元模拟混凝土,Link 8单元模拟钢筋,三维非线性弹簧单元Combine 39模拟钢筋-混凝土界面的粘结滑移关系,将Houde提出的钢筋-混凝土间的粘结滑移本构模型引入ANSYS中以确定Combine 39弹簧单元的荷载-位移关系式。此外,在现有混凝土裂缝宽度计算方法的基础上,推导出适用于有限元分析的裂缝宽度计算公式,并应用ANSYS软件提供的二次开发工具——参数化编程语言(APDL)编制程序,在ANSYS后处理中实现混凝土构件裂缝宽度的计算功能。算例分析表明,与现有方法相比,该方法能更准确地计算各级荷载作用下钢筋混凝土构件的裂缝宽度。 相似文献
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针对现行的JTS 167—2018《码头结构设计规范》中偏置荷载弯矩计算宽度公式b′c=0.5bc+y的限制条件“当bc>B时,取bc=B”将导致在板宽B<0.5l0时,内力计算结果偏大的问题,进行现行规范JTS 167—2018与旧规范JTJ 291—1998相关条文的对比分析。将有限元软件与规范公式计算的面板在集中荷载作用下弯矩及内力结果进行比较。结果表明,偏置荷载下的弯矩计算宽度b′c=0.5bc+y的限制条件“当b′c>B时,取b′c=B,当b′c<B时,取b′c=0.5bc+y”较符合面板受力的实际情况。 相似文献
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通过对配置HRBF500高强钢筋的混凝土梁在集中荷载作用下的受剪试验,并依据《水运工程混凝土结构设计规范》条文规定,研究该高强钢筋在港口工程混凝土受剪构件中的应用。试验观测构件斜裂缝开展规律及破坏形态,采集构件不同状态时的荷载数据。依据《港口工程荷载规范》条文规定,并引入荷载长期影响系数,分析构件斜截面极限承载力及正常使用极限状态斜裂缝宽度。研究结果表明,配置高强钢筋的混凝土梁斜向开裂规律与普通梁基本相同,其钢筋强度可以被充分利用,基于水运规范所得极限承载力和考虑荷载长期影响的正常使用阶段斜裂缝宽度满足要求,且有较好的安全储备。 相似文献
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Fatigue crack propagation behavior under superimposed stress histories containing different frequency components with several mean stress conditions was investigated. Numerical simulation of fatigue crack propagation based on an advanced fracture mechanics approach using the RPG (Re-tensile Plastic zone Generating) stress criterion for fatigue crack propagation was improved to extract the effective part from the applied stress history for fatigue crack propagation. The parameter, which is based on the plastic hysteresis energy consumed in the vicinity of a crack tip, was applied and implemented into the numerical simulation code of fatigue crack propagation. Fatigue crack propagation tests under various superimposed stress conditions with several mean stress conditions were performed and compared with the fatigue crack propagation histories obtained from the improved numerical simulations. These comparisons show the validity of the proposed procedure for extracting the effective stress history from the superimposed stress histories with different frequency components and mean stresses. Additionally, practical fatigue strength evaluations based on the linear cumulative fatigue damage parameter were conducted to investigate the tendency of the fatigue damage value under these stress conditions. 相似文献
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An efficient numerical analysis procedure based on FEM was implemented for evaluating the effect of welding residual stress (WRS) on mixed-mode stress intensity factors (MM-SIFs) for a non-planar surface-cracked tubular T-joint with a rounded weld toe. A multi-pass welding simulation was carried out using real welding conditions by means of an effective in-house welding simulation code. A fully compatible 3D finite element mesh generation system was implemented to model non-planar perpendicular surface-cracked tubular T-joints with rounded weld toes. The adequacy of the mesh generation system was verified with the reference solutions. A fully automated mapping code was developed to assign the six components of the simulated WRS to each element face over the crack surface. A developed fracture approach was employed to accurately compute MM-SIFs resulting from WRS in which normal and shear components of WRS were considered. MM-SIFs were calculated carefully for several surface cracks with different shapes under different loading conditions. The behavior of MM-SIF solutions resulting from the combination of external load and WRS was influenced significantly by the behavior of those produced due to WRS only. In addition, the value of the computed SIFs resulting from the combination of external load and WRS was almost doubled for mode-I SIF compared to those obtained by external load only and WRS only especially near the crack end locations. The behavior of the calculated fracture parameters was also discussed. 相似文献
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为研究试样厚度对船用钢疲劳裂纹扩展速率的影响,设计并实施两组不同厚度的紧凑拉伸试样进行疲劳裂纹扩展速率试验,同时建立了三维疲劳裂纹扩展有限元模型,分别基于线弹性理论和弹塑性理论对应力强度因子进行了计算,并分析了试样厚度对裂纹扩展速率的影响。试验与计算结果的综合分析表明:相同应力水平下,薄试样裂纹尖端的塑性区明显大于厚试样,且裂纹尖端应力强度因子值大于理论经验计算结果可达23.25%,因此,在材料裂纹扩展速率试验前,特别是试样厚度尺寸较小时,应充分考虑试样的厚度效应,参考基于弹塑性理论计算得到的应力强度因子结果,同时有必要针对当前试样及材料进行专门的裂纹扩展速率试验,以得到准确裂纹扩展参数结果。 相似文献