冷轧带肋钢筋砼板类构件试验研究与应用

本文基于７２块冷轧带肋钢筋砼板类构件试验，对应用冷轧带肋钢筋的预应力砼空心板，现浇楼板，叠合板的工作性能，承载力与经济效益进行了较深入的研究与分析，试验感化研究结果表明，冷轧带肋钢筋砼板类构件中的着显著的经济效益与广阔的应用前景，应加快推广应用。     

冷轧带肋钢筋混凝土板类构件试验研究与应用

本文基于７２块冷轧带肋钢筋砼板类构件试验，对应用冷轧带肋钢筋的预应力砼空心板、现浇楼板、叠合板的工作性能、承载力与经济效益进行了较深入的研究与分析。试验研究结果表明，冷轧带肋钢筋砼板类构件中有着显著的经济效益与广阔的应用前景，应加快推广应用。     

预制空心板周边裂缝的原因及防治措施

分析了楼房预制空心板周边裂缝产生的原因,提出了防治措施     

现浇空心楼盖抗剪性研究

通过对《混凝土结构设计规范》、《现浇混凝土空心楼盖结构技术规程》和实验结论的研究,分析现浇空心楼板的结构特点,从而得出了现浇空心楼盖抗剪设计的必要性.在空心楼盖的抗剪验算时,要考虑到横肋与顺肋板之间的区别和箍筋在其中起到的作用,并给出了计算公式.     

现浇空心楼盖抗剪性研究

通过对《混凝土结构设计规范》、《现浇混凝土空心楼盖结构技术规程》和实验结论的研究,分析现浇空心楼板的结构特点,从而得出了现浇空心楼盖抗剪设计的必要性。在空心楼盖的抗剪验算时,要考虑到横肋与顺肋板之间的区别和箍筋在其中起到的作用,并给出了计算公式。     

曲线桥非预应力钢筋混凝土空心板整体现浇施工技术研究

结合工程实例详细介绍了林光沟桥曲线空心板整体现浇的施工工艺及施工技术，由于采用了纸内内模施工工艺，一举解决了空心板整体现浇的施工技术难题。     

预制楼板顺板缝开裂现象的防治措施综述

针对多层房屋中经常出现的预制楼板层顺板侧缝开裂的现象,从楼板布置,安装及板缝施工等各方面综合阐述了这一质量通病的多种防治措施,方法简单易行,操作实用方便。     

预制预应力混凝土连续叠合板弯矩调幅试验研究

为研究预制预应力混凝土连续叠合板的内力重分布及弯矩调幅规律,完成了3块预应力混凝土连续叠合板的静载试验.试验结果表明:(a)预制预应力混凝土连续叠合板的内力重分布是由开裂引起的,随着连续叠合板裂缝的发展及塑性铰的产生不断调整各截面的内力;(b)预制预应力混凝土连续叠合板的中间支座调幅系数取值宜控制在20％以内.     

预应力混凝土空心叠合板试验

针对现有的一般预应力空心叠合板楼盖板较厚、自重较大等缺点,提出了一种新型的预应力混凝土空心叠合板。通过对3块简支板、3块简支叠合板和1块两跨连续叠合板进行静力荷载试验,分析了这种叠合板在静力荷载作用下的裂缝、承载力、挠度等特点,研究了其开裂荷载和极限承载力较高的原因。结果表明：这种预应力空心叠合板具有良好的抗裂性能和较高的极限承载能力;其开裂弯矩、极限承载力、挠度可按《混凝土结构设计规范》（GB50010--2002）进行计算,为这种叠合板的设计和工程应用提供了依据。     

钢筋砼双向板的试验研究

本文为“钢筋砼双向板满足使用要求的设计研究”的试验部分，着重讨论了钢筋砼双向板在不同受力阶段的变形性能及裂缝分布规律，通过与弹性计算值的比较，提出了挠度计算的“弹性刚度折减法”以及荷载作用方式对结构内力分布的影响。     

Influence of fractality of fracture surfaces on stress and displacement fields at crack tips

In the classic theory of fracture mechanics, expressions for calculating the stresses and displacements in the vicinity of the crack tip are deduced on the basis of the assumption that a fracture surface is a smooth surface or that a crack is a smooth crack. In fact, the surface of a crack formed during the fracture is usually very irregular. So the real asymptotic form of the stress and displacement fields at the crack tip is different from the classic one. Considering the irregularity of a real fracture surface or a real crack profile, the crack is taken as a fractal one, and then the real asymptotic form at the crack tip is developed by applying Griffith’s energy balance principle and fractal geometry. Through the developed asymptotic form, it is discovered that the fractality of the crack reduces the stress singularity at the crack tip.

     

Influence of fractality of fracture surfaces on stress and displacement fields at crack tips

In the classic theory of fracture mechanics, expressions for calculating the stresses and displacements in the vicinity of the crack tip are deduced on the basis of the assumption that a fracture surface is a smooth surface or that a crack is a smooth crack. In fact, the surface of a crack formed during the fracture is usually very irregular. So the real asymptotic form of the stress and displacement fields at the crack tip is different from the classic one. Considering the irregularity of a real fracture surface or a real crack profile, the crack is taken as a fractal one, and then the real asymptotic form at the crack tip is developed by applying Griffith’s energy balance principle and fractal geometry. Through the developed asymptotic form, it is discovered that the fractality of the crack reduces the stress singularity at the crack tip.     

面板堆石坝裂缝机理及防裂措施

针对面板经常出现裂缝问题,对面板的裂缝机理进行了分析。结果表明，造成面板裂缝的主要原因是千缩裂缝、温度裂缝和结构性裂缝。为达到减少裂缝的目的，从不同方面对防止面板裂缝提出了应对措施。     

沥青路面多裂纹断裂分析

沥青路面通常在表面裂纹和基础裂纹共存状况下服务。基于断裂力学理论,采用无网格伽辽金/有限元耦合法,对同时含有面层表面裂纹和基层底面裂纹的沥青路面进行了断裂分析,研究了行车荷载行驶过程中裂纹尖端应力强度因子的变化规律。结果显示,在车轮荷载行驶通过基层底面裂纹上方的过程中,基层底面裂纹的复合型应力强度因子K＊存在一个最大极值,且这个最大值不是出现在车轮荷载位于基层正上方的时候;表面裂纹的应力强度因子K1和K2随着交通荷载驶近表面裂纹而逐渐增大,而且增大的速率也逐渐上升;相对于基层底面裂纹,表面裂纹受荷载位置影响更显著。     

高强度钢随机载荷下裂纹扩展模型

工程结构在全寿命周期内大多都承受随机载荷作用，随机载荷中载荷顺序对裂纹扩展有显著影响．用基于裂纹闭合现象的裂纹扩展模型依次模拟恒幅载荷、过载峰及随机载荷作用下的疲劳裂纹扩展．通过裂纹张开应力反映裂纹闭合效应，将Paris公式计算疲劳裂纹扩展，将有效应力强度因子范围代入Paris公式中计算，并用高强度钢程序块载荷下疲劳实验结果与计算结果比较．结果证明，基于裂纹闭合现象的裂纹扩展模型能很好地模拟随机载荷下的疲劳裂纹扩展，理论计算结果与试验结果相吻合，具有工程实用价值．     

管道漏磁内检测裂纹缺陷仿真与实验研究

针对管道漏磁内检测中裂纹与磁化方向角度过小难以识别问题,分析了直流电磁铁轴向励磁条件下裂纹角度对漏磁检测信号的影响以及裂纹漏磁信号的特征。采用Comsol有限元仿真软件,对管道内壁不同角度0.2 mm裂纹缺陷进行了仿真分析;搭建了直流电磁铁轴向励磁实验平台,采用电火花技术加工不同角度裂纹试件,进行裂纹角度问题的拖拉实验。结果表明,裂纹与磁化方向最小可检测角度为25°;随着裂纹角度的减小,漏磁信号峰值逐渐减小,信号跨度越大,噪声信号影响越大;当磁化方向与裂纹垂直时,漏磁信号幅值最大跨度最小,磁化方向与裂纹平行时无漏磁信号产生。     

疲劳裂纹在焊接接头中的扩展及裂纹闭合的研究

焊接接头疲劳裂纹的扩展过程中存在着闭合现象．本文提出了考虑到宏观力学不均匀性时焊接接头的实验及数值分析模型,通过实验及弹塑性有限元法研究了焊接接头疲劳裂纹扩展及闭合现象,分析了裂纹尖端应力分布的变化．结果表明,焊接接头疲劳裂纹的扩展受裂纹闭合的影响,加载过程中裂纹尖端应力过零时对应的外载可作为裂纹张开载荷Pop．同时讨论了力学不均匀性影响疲劳裂纹扩展的本质．     

Influence of fractality of fracture surfaces on stress and displacement fields at crack tips

In the classic theory of fracture mechanics,expressions for calculating the stresses and displacements in the vicinity of the crack tip are deduced on the basis of the assumption that a fracture surface is a smooth surface or that a crack is a smooth crack.In fact,the surface of a crack formed during the fracture is usually very irregular.So the real asymptotic form of the stress and displacement fields at the crack tip is different from the classic one.Considering the irregularity of a real fracture surfac...     

泛函分析在裂缝简支梁损伤检测及参数识别中的应用

利用扭曲弹簧模型，对裂缝简支梁前三阶固有频率的变化与裂缝深度及位置的关系进行了理论分析。对简支梁遭受多种裂缝局部损伤的动力特性进行试验研究，并通过泛函分析及泛函极值定理确定出局部裂缝损伤位置。然后再代入弹簧刚度模型求出裂缝深度参数，识别结果与实际模拟结果平均误差为5．0％。结果表明，用固有频率结合泛函分析方法，获得的裂缝检测方法检测精度较高，裂缝位置识别结果最小误差为2．20％，深度识别结果最小误差为2．10％，并克服了仅仅依靠固有频率难以确定裂缝损伤位置的缺点。     

Wing crack model subjected to high hydraulic pressure and far field stresses and its numerical simulation

By considering the effect of hydraulic pressure filled in wing crack and the connected part of main crack on the stress intensity factor at wing crack tip, a new wing crack model exerted by hydraulic pressure and far field stresses was proposed. By introducing the equivalent crack length l _eq of wing crack, two terms make up the stress intensity factor K _I at wing crack tip: one is the component K _I⁽¹⁾ for a single isolated straight wing crack of length 2l subjected to hydraulic pressure in wing crack and far field stresses, and the other is the component K _I⁽²⁾ due to the effective shear stress induced by the presence of the equivalent main crack. The FEM model of wing crack propagation subjected to hydraulic pressure and far field stresses was also established according to different side pressure coefficients and hydraulic pressures in crack. The result shows that a good agreement is found between theoretical model of wing crack proposed and finite element method (FEM). In theory, an unstable crack propagation is shown if there is high hydraulic pressure and lateral tension. The wing crack model proposed can provide references for studying on hydraulic fracturing in rock masses.