共查询到18条相似文献，搜索用时 812 毫秒
1.
研究目的:为了解决不均匀锈蚀情况下钢筋锈蚀率的计算问题,实现锈胀开裂构件的锈蚀率无损检测,采用理论分析和试验研究相结合的方法,建立锈蚀梁钢筋最大锈蚀率的计算模型。创新要点:考虑了邻近位置混凝土开裂的影响,基于理论分析建立了不同位置的锈胀裂缝宽度修正模型。研究方法:首先通过理论分析建立考虑相邻测点相互影响的锈胀裂缝宽度修正模型,然后根据锈蚀物体积膨胀几何模型,建立基于锈胀裂缝宽度的锈蚀率计算公式,最后通过七根锈蚀梁的加速锈蚀试验验证了模型的准确性。重要结论:根据对开裂后钢筋与锈蚀物膨胀体积的量化分析,锈胀裂缝宽度与钢筋锈蚀率近似呈线性变化。电解液加速腐蚀试验结果表明,提出的锈蚀率计算方法得到的最大锈蚀率与实际平均值的比值在1.4–2.4之间,与实际情况符合较好。 相似文献
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为了研究锚固区混凝土锈胀开裂后构件的锚固可靠度的变化情况,采用一次二阶矩方法分析了锈胀裂缝的长度及宽度、保护层厚度、钢筋锚固长度以及配箍率等参数对混凝土简支梁锚固可靠度的影响.分析结果表明:当保护层刚开裂时,锈胀裂缝长度对锚固可靠指标β0的影响很小,此后,随着裂缝宽度的增加,β0有了明显的降低;保护层厚度和锚固长度的变化对β0有相当大的影响;改变箍筋的直径或间距对锚固抗力的影响很小,因此,β0变化的幅度也很小. 相似文献
3.
为研究钢筋锈蚀后再生混凝土框架节点的破坏特征和抗震性能,对钢筋未锈蚀、锈蚀而保护层未开裂、平均锈胀裂缝宽度为0．2mm及平均锈胀裂缝宽度为0．4mm四种情况下的再生混凝土及普通混凝土框架边节点,进行了低周反复荷载对比试验;观察节点的受力过程及破坏形态,分析试件的荷载一位移滞回曲线、承载能力、强度和刚度退化、延性以及耗能能力等力学特性．结果表明：相同锈蚀程度下,再生混凝土节点的强度比普通混凝土节点小,再生混凝土节点的刚度退化比普通混凝土节点严重,再生混凝土节点表现出更好的延性,再生混凝土耗能较普通混凝土耗能弱;随着钢筋锈蚀程度的增加,再生混凝土与普通混凝土节点的强度降低,刚度减小,延性减小,耗能能力降低． 相似文献
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罗纪彬 《湖南广播电视大学学报》2009,(3):46-49
根据混凝土碳化及其引起的钢筋锈蚀的机理,建立了钢筋混凝土构件的劣化模型。利用Monte Carlo模拟方法分别研究了一般运营和密集运营两种荷载模型下钢筋混凝土桥梁的时变可靠性,讨论了保护层厚度、混凝土强度、钢筋锈蚀损失率对混凝土耐久性的影响。研究表明：在服役过程中,由于大气环境的作用,混凝土碳化、钢筋锈蚀、桥梁结构可靠指标不断降低,混凝土的耐久性能不断下降;混凝土保护层厚度和混凝土抗压强度对可靠度指标的影响明显,而钢筋腐蚀率的影响不是很明显。 相似文献
5.
对瑞安市教座典型的混凝土结构构筑物的腐蚀破坏状况进行了调查分析．结果表明,飞云江沿岸混凝土结构腐蚀比较严重,许多构筑物的混凝土保护层过薄,有的出现了内部钢筋锈蚀、混凝土顺筋开裂和剥落等现象．主要原因有结构设计不合理、施工质量差、化学侵蚀等． 相似文献
6.
通过钢筋位移混凝土保护层厚度的变化对混凝土受弯构件结构性能的影响进行定量分析结果表明,钢筋位移保护层厚度过大是造成混凝土结构性能的承载力下降、裂缝宽度超标、挠度超限的重要原因.从而导致混凝土结构存在安全隐患,影响工程结构的安全性、适用性和耐久性. 相似文献
7.
林婷玉 《世界华商经济年鉴·科学教育家》2013,(6)
对于混凝土桥梁在建造和使用过程中,因出现裂缝而影响工程质量.特别是有些裂缝在使用荷载或外界物理、化学因素的作用下,不断的生和扩展,引起混凝土碳化、保护层剥落、钢筋腐蚀,使混凝土的强度和刚度受到削弱,耐久性降低,严重时甚至发生垮塌事故,危害结构的正常使用,必须加以控制.我国现行公路、铁路、建筑、水利等部门设计规范均采用限制构件裂缝宽度的办法来保障混凝土结构的正常使用.工程实践证明很多裂缝是可以克服和控制的. 相似文献
8.
退化钢筋混凝土桥梁概率耐久性评估方法 总被引：1，自引：0，他引：1
提出了考虑时间、空间变异特性的退化钢筋混凝土桥梁耐久性概率评估的随机有限元方法.首先,通过考虑钢筋与混凝土之间时变的粘结滑移关系及腐蚀钢筋的应力应变关系,采用弥散裂纹方法对退化钢筋混凝土桥梁进行有限元分析.然后,提出了退化钢筋混凝土桥梁耐久性概率评估的随机有限元分析方法,基于文献及现场调查的数据,采用蒙特卡罗仿真方法对... 相似文献
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氯盐外侵和内掺引起的混凝土内钢筋锈蚀特征的比较研究 总被引：1，自引：0，他引：1
氯盐外侵和内掺氯盐是耐久性研究经常采用的两种加速试验方法．通过大量的构件破型发现：氯盐外侵试件中钢筋的锈蚀为靠近混凝土保护层一侧锈蚀比较严重,而背向一侧几乎没有发生;内掺氯盐试件中钢筋的锈蚀特征为钢筋四周均发生锈蚀,靠近混凝土保护层一侧的锈蚀较背向保护层的一侧严重．理论分析和试验研究结果表明混凝土内钢筋锈蚀特征取决于钢筋内外表面的活化状态及钢筋内外表面间宏观腐蚀电流Ig． 相似文献
11.
EFFECT OF CORROSION ON BOND BEHAVIOR AND BENDING STRENGTH OF REINFORCED CONCRETE BEAMS 总被引：1，自引：0，他引：1
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｒｅｉｓｇｒｏｗｉｎｇｃｏｎｃｅｒｎｆｏｒｃｏｒｒｏｓｉｏｎｄａｍ ａｇｅｉｎｒｅｉｎｆｏｒｃｅｄｃｏｎｃｒｅｔｅ (ＲＣ)ｓｔｒｕｃｔｕｒｅｓｗｉｔｈｓｅｖｅｒａｌｄｅｃａｄｅｓ’ｓｅｒｖｉｃｅ.Ｔｈｅｒｅｉｎｆｏｒｃｅｍｅｎｔｃｏｒ ｒｏｓｉｏｎｏｆＲＣｃｏｎｓｔｒｕｃｔｉｏｎｓｐｒｏｂａｂｌｙｉｓｔｈｅｍｏｓｔｓｉｇｎｉｆｉｃａｎｔｐｒｏｂｌｅｍａｎｄｏｕｔｗｅｉｇｈｓｏｔｈｅｒｆｏｒｍｓｏｆｄｅｔｅｒｉｏｒａｔｉｏｎ .ＳｔｕｄｉｅｓｂｙＰｅａｔｔｉｅｅｔａｌ.( 1 9… 相似文献
12.
Analytical modeling for corrosion-induced cover cracking of corrosive reinforced concrete structures 总被引：1，自引：1，他引：0
An analytical model for predicting the corrosion-induced cracking of concrete cover of reinforced concrete(RC) structures was developed.The effects of influence factors such as practical initial defects,corrosion rate,strength and elastic modulus of concrete on the corrosion-induced cracking of concrete cover were investigated.It was found that the size of practical initial defects was the most effective factor.Therefore,improving the compactness of concrete is an effective way to improve the durability of RC structures.It was also demonstrated that the accelerated corrosion tests may be unfavorable in the study of the relationship between cracking time and crack width. 相似文献
13.
There is growing concern for corrosion damage in reinforced concrete structures with several decades’ service. Pullout tests
and beam tests were carried out to study the effect of reinforcement corrosion on the bond behavior and bending strength of
reinforced concrete beams. The bond strength of plain bars and concrete initially increases with increasing corrosion, then
declines. The turning point depends on the cracking of the concrete cover. The bond strength of deformed bars and concrete
increases with corrosion up to a certain amount, but with progressive increase in corrosion, the bond strength decreases,
and the cracking of the concrete cover seems to have no effect on the bond strength. On the basis of test data, the bond strength
coefficient recommended here, which, together with the bond strength of uncorroded steel bars and concrete, can be used to
easily calculate the bond strength of corroded steel bars and concrete. The bond strength coefficient proposed in this paper
can be used to study the bond stress-slip relationship of corroded steel bars and concrete. The bending strength of corroded
reinforced concrete beams declines with increasing reinforcement corrosion. Decreased bending strength of corroded RC beam
is due to reduction in steel bar cross section, reduction of yield strength of steel bar, and reduction of bond capacity between
steel bar and concrete.
Project supported by Cao Guanbiao Key Technology Development Founding of Zhejiang University and Construction Ministry of
China. 相似文献
14.
Time-to-cracking of the concrete cover induced by the steel corrosion is one of the critical problems faced by engineers, operators and asset managers in making strategies for the maintenance and repairs of reinforced concrete (RC)structures affected by corrosion. In this paper, a theoretical model for predicting the time-to-cracking is derived by assuming the bond between the steel bar and the concrete as a linear combination of perfectly smooth and bonded. The model takes into account the characteristics of existing exiguous flaws and initial cracks in the concrete before the load acting on RC structures. The validity of the proposed model is preliminarily verified by comparing the obtained results with the available experimental results. A remarkable advantage of the proposed method is its application to the prediction of the service life of RC structures, made of the deformed steel bars as well as the round bars. By determining an experimental constant α, which is related to the interface bond state between the steel bar and the concrete, the service life of RC structures can be predicted using the proposed scheme. Analysis of major factors affecting the time-to-cracking demonstrates that the length of the initial crack affects the service life of RC structures significantly. Moreover, the larger cover thickness and the smaller diameter of the steel bar within a certain range are beneficial to prolonging the time-to-cracking. 相似文献
15.
混凝土结构钢筋腐蚀的抑制措施 总被引：2，自引：0，他引：2
陈丽金 《福建工程学院学报》2003,1(1):99-101
混凝土结构钢筋腐蚀是影响结构耐久性和安全性的重要因素之一。根据混凝土结构钢筋腐蚀机理，认为抑制钢筋腐蚀，应控制好混凝土保护层厚度、氯离子含量和混凝土裂缝宽度，并应采取有效措施提高温凝土的密实性、掺入引气剂、合理选择饰面材料等。 相似文献
16.
Dong-ming Yan Hua-wei Yin Cheng-lin Wu Yan-long Li Jason Baird Gen-da Chen 《浙江大学学报(A卷英文版)》2016,17(9):689-701
In this study, two full-size concrete walls were tested and analyzed to demonstrate the effectiveness of a chemically reactive enamel (CRE) coating in improving their mechanical behavior under blast loading: one with CRE-coated rebar and the other with uncoated rebar. Each wall was subjected in sequence to four explosive loads with equivalent 2, 4, 6-trinitrotoluene (TNT) charge weights of 1.82, 4.54, 13.6, and 20.4 kg. A finite element model of each wall under a close-in blast load was developed and validated with pressure and strain measurements, and used to predict rebar stresses and concrete surface strain distributions of the wall. The test results and visual inspections consistently indicated that, compared with the barrier wall with uncoated reinforcement, the wall with CRE-coated rebar has fewer concrete cracks on the front and back faces, more effective stress transfers from concrete to steel rebar, and stronger connections with its concrete base. The concrete surface strain distributions predicted by the model under various loading conditions are in good agreement with the crack patterns observed during the tests. 相似文献
17.
Corrosion of steel rebar is the most important durability problem of reinforced concrete. The aim of this research was to investigate the corrosion behavior of steel rebar in simulated pore solutions and gangue-blended cement mortar. The simulated pore solutions were based on the pore solution composition ofgangue-blended cement. The pH and CI concentration of simulated pore solutions had significant effects on corrosion potential. However, an increase in pH reduced the influence of Cl- concentration on corrosion potential. The corrosion behavior of steel rebar in gangue-blended cement is different from that in simulated solutions. The gangue cementitious mortar surrounding steel rebar provides stable passivity environments for steel, leading to a decrease in ion diffusion coefficients. Alternating current impedance （ACI） analysis results indicated that the indicator Rc for concrete resistivity is higher for gangue mortar than for ordinary Portland cement （OPC）, which improves its corrosion potential. The results from energy dispersive X-ray analysis （EDX） showed more aluminates and silicates at the rebar interface for gangue-blended cement. These aluminates improve the chloride binding capacity of hydrates in mortar, and increase the corrosion protection of steel rebar. 相似文献
18.
张萍 《廊坊师范学院学报(自然科学版)》2014,(3):66-68
针对混凝土结构中钢筋的锈蚀问题,总结了锈蚀钢筋力学性能的研究方法、锈蚀对钢筋力学性能的影响及锈蚀钢筋力学性能的变化规律等研究现状,提出了有待继续研究的问题,为进一步建立锈蚀钢筋模型和加强锈蚀钢筋防护奠定基础. 相似文献