钢筋混凝土构件裂缝原因分析及加固方法探讨

从设计和施工两方面分析了钢筋混凝土结构构件产生裂缝的原因,分别介绍了钢筋混凝土构件裂缝的两大类加固方法：直接加固法和间接加固法,并结合工程实例针对具体情况进行了阐述,以期指导实践,合理有效治理裂缝。     

Corrosion damage assessment and monitoring of large steel space structures

Large steel space structures, when exposed to a harsh corrosive environment, are inevitably subjected to atmospheric corrosion and stress corrosion cracking. This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion. The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced. The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking. Based on the results, the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.     

Corrosion damage assessment and monitoring of large steel space structures

Large steel space structures, when exposed to a harsh corrosive environment, are inevitably subjected to atmospheric corrosion and stress corrosion cracking. This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion. The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced. The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking. Based on the results, the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.     

钢-混凝土组合连续梁混凝土翼板纵向开裂问题的研究

实验表明在竖向集中荷载作用下 ,布置单排栓钉的钢 混凝土组合梁的混凝土翼板常常出现纵向开裂。从而导致混凝土翼板与钢梁的连接作用大大降低 ,致使构件达不到设计承载力而破坏。作者从理论上分析了混凝土翼板纵向开裂的原因 ,推导了纵向开裂弯矩的计算公式 ,提出了避免出现纵向开裂措施。     

巧验受弯构件裂缝宽度

本文就钢筋混凝土结构中受弯构件在荷载作用下产生裂缝 ,从结构设计方面对裂缝宽度提出了一种快速有效的验算方法 ,简化了设计程序 ,同时满足了《规范》的要求     

防水混凝土的结构设计与配合比设计探讨

阐述了防水混凝土设计考虑的重点应是避免混凝土开裂的观点,并重点从造成混凝土开裂的原因入手,从防水混凝土结构设计和配合比设计的角度,探讨了避免和减少混凝土开裂渗漏的措施.即结构设计人员应对防水混凝土不同部位的配筋布置作出相应的调整,在满足荷载的前提下,尽量多使用较细而分布较密的钢筋,并应对混凝土的膨胀率作出要求;而配合比设计人员应选择合理的水泥、掺合料、膨胀剂,配制满足膨胀率要求、施工性能良好的混凝土,满足抗裂防水工程的需要.     

核电站安全壳钢衬里作用探讨

核电站核反应堆的维护结构安全壳钢衬里,其重要性不言而喻。安全壳内部钢衬里正是基于密封性能的重要考虑,抵御异常事故工况下的核污染扩散。当前,对于钢衬里的重要作用和结构形式人类的认识也是逐渐深入,核电站安全壳钢衬里已简单退化成核电站安全壳密封性能的需求,不再充当结构强度需要,但是对于壳体混凝土裂缝开展隐患起到有利的降低作用。作为钢衬里密封板既充当密封性能作用,又降低了混凝土的收缩和徐变、减少了混凝土开裂风险;对于后者结构性功能很少受到人们的重视,作为弹性结构设计也多被忽略。通过核电站安全壳钢衬里的影响作用分析、特别是对主体结构混凝土开裂影响分析指导混凝土结构的设计,确保结构设计的特殊性功能需求。     

钢-混组合连续梁桥墩顶应力计算研究

基于有限元分析,对某4跨钢-混组合连续梁桥进行混凝土面板与钢梁的3个不同建模形式进行分析,对比规范要求的不同建模形式下墩顶负弯矩区混凝土面板钢筋应力与钢梁应力的变化关系.研究结果表明:将开裂区钢筋等效为混凝土,与钢梁形成组合截面的建模形式计算得到的钢筋换算应力与钢梁应力均适中,所以推荐采用该种建模方式进行计算;此外在偏...     

连续刚构桥底板防崩裂设计研究

连续刚构桥是国内外应用较为广泛的桥型,但该桥型大多会发生底板崩裂病害,严重影响其运营安全和使用寿命。文章以云南某桥为实例,通过有限元软件建模计算,分析了该桥底板崩裂的原因,发现抗崩钢筋设计以及波纹管施工定位误差是该桥发生崩裂病害的重要原因,其中抗崩钢筋可以采用不对称设计,希望对类似工程提供参考。     

预应力混凝土钢桁架叠合板受弯性能试验与理论研究

通过在预应力混凝土平板上增设钢桁架方式,提出一种预应力混凝土钢桁架叠合板,解决了现阶段其他类型叠合板用预制底板存在开裂荷载较低、临时支撑密集等问题。为研究不同桁架类型对预制底板及叠合板受弯性能的影响,对6块预制底板试件和4块叠合板试件开展了静力加载试验,得到其破坏特征、开裂荷载、挠度曲线及应变分布等。试验结果表明：钢桁架能够显著提高底板的开裂荷载,其中钢管桁架底板试件的开裂荷载最高,达到平板试件的194%以上,适用跨度最大达到9m;不同桁架类型底板试件的破坏模式存在一定差异,钢板桁架、钢管桁架和钢筋桁架预制底板的破坏特征分别为钢板屈曲、焊缝断裂及钢筋弯曲;钢桁架能显著增强底板及叠合层混凝土的整体受力及协同工作性能;桁架类型对叠合板的受弯性能影响较小,不同桁架类型叠合板的开裂荷载均相同,开裂挠度差异在10%以内。基于试验结果,建立了底板上弦失稳弯矩计算公式,并提出预制底板失效弯矩应取开裂弯矩与上弦失稳弯矩的较小值,计算值与试验值吻合较好。     

Rissbreitenberechnung bei “Kombibewehrung”

Crack Width Limitation for Combined Reinforcement In recent years, steel fibre concrete has more and more found a wide spread application in structural engineering. This applies to building members made from steel fibre concrete or in combination with normal re‐bar reinforcement (combined reinforcement). In this context the question of crack width limitation very often has to be answered, and the interaction of the steel fibres with the rebars has to be observed. Some design rules are available in the relevant literature, whereas the design rules for a combined reinforcement use the basics of DIN 1045‐1. This paper deals with the applicability of these design proposals for a combined reinforcement, based on research results and some characteristics in the design consideration of the post‐cracking tensile strength of steel fibre concrete will be given.     

钢骨混凝土梁的设计方法

本文介绍了钢骨混凝土梁正截面承载力、抗弯刚度和裂缝宽度的设计计算方法,供工程设计人员参考.     

武汉长江隧道抗裂混凝土的研究

采用<混凝土结构耐久性设计与施工指南>CCES01-2004提供的平板开裂试验方法,研究了分别掺加凯泰改性聚丙烯纤维、有机仿钢丝纤维、钢纤维的混凝土的塑性收缩开裂性能.分析了不同纤维品种、掺量对混凝土开裂性的影响.研究结果表明,聚丙烯纤维对于有效抑制裂缝的产生和扩展,提高混凝土抵抗塑性收缩的能力效果最为明显,其次是钢纤维和有机仿钢丝纤维.     

应用能量守恒原理设计钢纤维喷射混凝土衬砌厚度的方法

不同于普通混凝土，钢纤维混凝土在破坏时由于钢纤维的拔出作用可以消耗大量的能量，系统地研究钢纤维混凝土的这一本质特征对钢纤维混凝土结构的设计有着重大的指导意义。从室内试验结果出发，应用概率统计方法对钢纤维喷射混凝土的指标进行了可靠性分析，得出实际可以接受的保证率下的钢纤维喷射混凝土能量指标，然后通过相关能量公式的推导，将韧性试验得到的钢纤维喷射混凝土的能量指标应用于较高等级围岩中隧道衬砌结构的设计。     

帽型截面钢-混凝土组合梁受弯强度

根据 12根帽型截面钢 -混凝土组合简支梁在外荷载作用下 ,开裂及破坏时应力 -应变关系 ,推导该组合梁开裂弯矩和极限弯矩 ,并将计算结果与试验结果进行比较 ,提出了设计方法和建议     

地毯式沥青混合料结构在小西冲大坡度弯道钢桥的创新研究地毯式沥青混合料结构在小西冲大坡度弯道钢桥的创新研究

可卷曲和延展性沥青混合料结构在安徽小西冲大坡度弯道钢桥的首次应用研究,地毯式沥青混合料创新了钢桥面的铺筑结构类型。混合料具有较高的耐疲劳性、反复弯曲应变性、抗高温变形和抗低温抗裂的复合性能。通过室内混合料的理论行为研究与现场铺筑工艺行为特征的演变过程,对今后特殊钢桥面的设计结构类型奠定了理论与实践基础。     

Ultimate strength of cracked plate elements under axial compression or tension

In addition to corrosion, fatigue cracking is another important factor of age related structural degradation, which has been a primary source of costly repair work of aging steel structures. Cracking damage has been found in welded joints and local areas of stress concentrations such as at the weld intersections of longitudinals, frames and girders. Fatigue cracking has usually been dealt with as a matter under cyclic loading, but it is also important for residual strength assessment under monotonic extreme loading, because fatigue cracking reduces the ultimate strength significantly under certain circumstances.In this paper, an experimental and numerical study on the ultimate strength of cracked steel plate elements subjected to axial compressive or tensile loads is carried out. The ultimate strength reduction characteristics of plate elements due to cracking damage are investigated with varying size and location of the cracking damage, both experimentally and numerically. Ultimate strength tests on cracked steel plates under axial tension and cracked box type steel structure models under axial compression are undertaken. A series of ANSYS nonlinear finite element analyses for cracked plate elements are performed. Based on the experimental and numerical results obtained from the present study, theoretical models for predicting the ultimate strength of cracked plate elements under axial compression or tension are developed. The results of the experiments and numerical computations obtained are documented. The insights developed will be very useful for the ultimate limit state based risk or reliability assessment of aging steel plated structures with cracking damage.     

Horizontal cracking of continuously reinforced concrete pavement under environmental loadings

The objective of this study is to identify the mechanisms and associated variables of horizontal cracking in continuously reinforced concrete pavement (CRCP) and to develop mitigation methodologies. To this end, the laboratory and field testing were carried out. The behavior of CRCP at relatively early ages under environmental loadings was measured and compared with numerical analysis. The effect of factors related to design, materials, and construction on the horizontal cracking potential was evaluated through the comprehensive numerical analysis. It is expected that this study could help develop or improve design standards and/or material or construction specifications to prevent distress from horizontal cracking in CRCP.     

配筋钢纤维混凝土梁正截面抗裂计算

通过对试验结果的统计分析 ,研究了钢纤维类型和钢纤维含量特征值对钢筋钢纤维混凝土和预应力钢纤维混凝土梁正截面抗裂弯矩的影响规律 ,分析了钢纤维对混凝土抗拉强度的增强效应与钢纤维对梁正截面抗裂度的增强效应之间的相关关系。提出了配筋钢纤维混凝土梁正截面抗裂弯矩计算建议 ,供修订我国的《纤维混凝土结构技术规程》及工程设计与施工参考