混凝土结构中钢筋锈蚀程度评估及预测试验研究

本文通过三类１８０根锈蚀试件的观察及２５８根钢筋的破型试验分析，提出了对混凝土构件中钢筋锈蚀程度进行及定量评定及预测的方法，得出了钢筋锈蚀与纵裂宽度、保护层厚度，钢筋直径及混凝土强度之间的关系公式，可为混凝土结构耐久性评估及可靠性鉴定提供科学的依据。     

钢筋锈蚀轴心受压混凝土柱承载力有限元分析

通过有限元软件ABAQUS建立数值模型研究钢筋锈蚀长度、粘结程度和锈蚀根数对钢筋锈蚀轴心受压混凝土柱承载力的影响。研究结果表明:粘结程度越低,锈蚀根数越多,钢筋锈蚀轴心受压混凝土柱承载力越低。     

大气环境混凝土中锈蚀钢筋性能和锈蚀模型试验研究

对大气环境混凝土中123根Ⅰ级和Ⅱ级锈蚀钢筋的力学性能进行了试验研究，讨论了屈服荷载、极限荷载和极限伸长率与锈蚀率之间的定量关系，分析了Ⅰ级和Ⅱ级锈蚀钢筋力学性能的异同。提出了钢筋锈蚀的三维椭球模型，以及钢筋锈蚀率的衡量方法。     

受拉钢筋严重锈蚀混凝土梁极限承载力有限元分析

运用ANSYS模拟分析了5根受拉钢筋严重锈蚀后混凝土梁的极限承载力,分析研究表明,用建立去除钢筋锈蚀周围混凝土的非完整实体模型,来分析研究钢筋严重锈蚀的混凝土梁极限承载力的方法是可行的.     

混凝土基本构件钢筋锈蚀前后性能试验研究

进行了３０多根钢筋锈蚀前后的混凝土受弯和受压构件的试验，研究了锈蚀后构件的受力性能和破坏形态，提出了钢筋锈蚀后受弯、轴心受压和大小偏心受压构件的承载能力计算方法，可为有关规程的编制和结构可靠性鉴定提供科学的依据     

厂房钢筋混凝土独立柱基酸腐蚀分析及加固设计

铜陵有色第一冶炼厂始建于20世纪50～60年代，后经多次改建、扩建，但污染腐蚀十分严重，主要表现为：(1)基础台阶表面混凝土疏松呈粉渣状，混凝土腐蚀深度达10～20cm；(2)地面以下柱根部位，钢筋保护层疏松、剥落，主筋外露锈蚀，个别柱根钢筋锈蚀断裂；(3)基础底板钢筋因有混凝土垫层及保护层的保护，除弯钩有锈蚀外基本完好。     

基于粘结强度变化的锈蚀钢筋混凝土梁受弯承载力的研究

基于锈蚀钢筋混凝土梁内钢筋与混凝土间粘结强度随锈蚀量的变化，对锈蚀梁的抗弯承载力进行了研究。钢筋锈蚀量较小时，锈蚀梁内钢筋与混凝土间粘结强度随锈蚀量增加而增加，锈蚀梁的力学性能同未锈蚀梁，可运用传统的梁理论计算锈蚀梁的抗弯承载力；随着钢筋锈蚀量的增加，钢筋与混凝土间粘结强度发生退化，锈蚀梁的力学性能介于粘结完好梁与无粘结梁之间，与传统的计算梁的抗弯承载力的方法不同，应考虑梁的各截面间相互作用。基于梁整体的受力平衡和变形协调，建立了考虑梁内粘结强度退化的锈蚀梁抗弯承载力模型。最后，通过54根锈蚀梁承载力试验结果，对文中建立的模型进行了验证分析，结果十分满意。     

混凝土中钢筋空间锈蚀特征参数的测试及分析

通过45个混凝土试件中135根光圆钢筋和带肋钢筋的加速锈蚀试验,采用研发的钢筋空间锈蚀形态测试装置和空间锈蚀特征参数分析方法,确定了混凝土中钢筋的空间锈蚀形态图像和空间锈蚀特征参数,进而定量分析了钢筋的质量锈蚀率与最大锈蚀深度、最小剩余截面积、最大截面锈蚀率和点蚀因子等空间锈蚀特征参数之间的相关性,为准确描述混凝土中钢筋的空间锈蚀分布形态提供了基础.结果表明:随着钢筋质量锈蚀率的增加,其最大锈蚀深度和最大截面锈蚀率呈线性增大,而最小剩余截面积和面积点蚀因子呈线性减小;随着钢筋最大锈蚀深度的增加,其最小剩余截面积呈线性减小;与光圆钢筋相比,带肋钢筋的非均匀锈蚀程度更高;与深度点蚀因子相比,钢筋面积点蚀因子与质量锈蚀率之间的相关性更加明显.     

大气环境条件下混凝土中钢筋的锈蚀

钢筋混凝土中的钢筋锈蚀，对结构的抗力、可靠性、使用寿命等有很大影响。在室外混凝土碳化深度达到钢筋表面时钢筋即开始锈蚀；在室内混凝土碳化深度超过钢筋表面20—30mm钢筋才开始锈蚀。钢筋锈蚀产物体积膨胀，使混凝土保护层开裂，从而加剧钢筋锈蚀：以混凝土抗压强度为主要参数建立混凝土碳化预测模型具有实际意义，可以在快速腐蚀试验和工程实测结果分析的基础上，建立混凝土保护层开裂前后钢筋锈蚀量模型和混凝土保护层开裂锈蚀条件。     

混凝土中钢筋杂散电流与氯离子耦合锈蚀行为

为了明确地铁混凝土结构中钢筋锈蚀行为,成型15组内置1根钢筋的砂浆试件,采用电化学测试技术模拟研究了地铁混凝土结构中钢筋锈蚀过程。结果表明:地铁混凝土结构中的钢筋锈蚀可分为初始腐蚀快速发展及腐蚀稳定发展2个阶段。地铁服役环境中杂散电流和氯离子对其锈蚀发展有显著影响,杂散电流强度和氯离子浓度越大,锈蚀越快。金相显微观察表明,地铁混凝土结构中钢筋锈蚀,主要是由于杂散电流引发,且与氯离子共同构成耦合作用,导致其钢筋加速破钝,产生严重锈蚀。     

黏砂变形GFRP筋黏结性能研究

基于18个梁式试验、42个Losberg拉拔试验以及6个标准拉拔试验,对黏砂变形GFRP筋与混凝土之间的黏结性能进行了较系统的研究。研究表明:黏砂变形GFRP筋梁式试件和拉拔试件的破坏形态均可分为拔出破坏和劈裂破坏两种,黏结长度大于5倍直径的GFRP筋试件发生劈裂破坏,小于5倍直径的试件发生拔出破坏,而对于黏结长度为5倍直径左右的试件,两种破坏形态均有可能发生;GFRP筋与混凝土之间的黏结强度约为相应带肋钢筋的0.64～1.27倍;随着黏结长度和直径的增加,GFRP筋与混凝土之间的黏结强度有所降低;基于梁式试验、Losberg拉拔试验与标准拉拔试验得到的GFRP筋与混凝土之间的黏结强度无显著差异。最后,综合考虑GFRP筋直径、表面形态、黏结长度等因素影响,提出GFRP筋与混凝土之间黏结强度、锚固长度的设计建议。     

Automated Estimation of Reinforced Precast Concrete Rebar Positions Using Colored Laser Scan Data

Precast concrete elements are widely adopted and the performance of precast structures is relying on the quality of connections between adjacent elements. For reinforced precast concrete elements, rebar positions are important for the overall structural performance, however, they are usually manually inspected. This study develops a technique for automated position estimation of rebars on reinforced precast concrete elements using colored laser scan data. A novel mixed pixel filter is developed to remove mixed pixels from the raw scan data based on both distance and color difference. A one‐class classifier is used for extracting rebars from all the data based on both geometric and color features of points. Furthermore, a novel rebar recognition algorithm is developed to recognize individual rebars based on two newly defined metrics. Experiments on two reinforced precast concrete bridge deck panels were conducted and showed that the proposed technique can accurately and efficiently estimate rebar positions.     

锈蚀钢筋混凝土墙体压弯承载力试验研究

考虑钢筋种类、混凝土强度、钢筋锈蚀率因素,对10个锈蚀钢筋混凝土墙体试件进行了压弯承载力试验研究。结果表明:钢筋锈蚀对墙体的承载力和挠度均有不同程度的影响;锈蚀钢筋混凝土墙体的承载力计算仍可近似采用平截面假定,但需引入协同工作系数考虑锈蚀钢筋与混凝土黏结滑移的影响;给出了锈蚀钢筋混凝土墙体的压弯承载力计算公式,并通过与试验结果比较,验证了计算公式的适用性。     

Corrosion behavior of epoxy/zinc duplex coated rebar embedded in concrete in ocean environment

The corrosion behavior of epoxy/zinc duplex coated rebar embedded in concrete is evaluated comparing with the black steel, galvanized and epoxy coated rebars for a long term in ocean environment. The effect of mechanical damages of epoxy coatings on the corrosion protection is examined. The epoxy coated and epoxy/zinc duplex coated rebars show the higher anti-corrosion performance than other types of rebars. However, once the epoxy coating is mechanically damaged, the more serious corrosion may occur in the damaged area of epoxy coated rebar in concrete. The epoxy/zinc duplex coating remains a good corrosion protection to steel in concrete even when suffering from some mechanical damages.     

拉拔条件下GFRP筋与混凝土粘结强度试验研究

采用Canadian Standards Association(CSA)标准规定的拉拔试验方法,考虑GFRP筋的种类、组分、直径、表面处理方法、肋间距、肋高度、肋宽度等因素,对GFRP筋与混凝土之间的粘结强度进行了试验研究。研究结果表明:试件的粘结破坏有筋表面变形的剪切、变形的脱落和肋间混凝土被剪碎三种形式;GFRP筋与混凝土的粘结强度低于钢筋与混凝土的粘结强度,大约为钢筋与混凝土粘结强度的65%~87%;GFRP筋的种类、直径、表面处理方法、肋高度、肋间距和肋宽度等因素对粘结强度的影响显著,但GFRP筋组分的影响不大;当肋间距为GFRP筋直径、肋高度为GFRP筋直径的6%时,GFRP筋与混凝土的粘结强度最高。     

混凝土中钢筋加速锈蚀试验适用性研究

钢筋锈蚀导致其屈服强度降低、力学行为改变,影响钢筋与混凝土之间的粘结性能,钢筋锈蚀量影响钢筋混凝土的失效模式。为研究锈蚀钢筋混凝土结构的相关性能,需要在较短时间内得到所需的锈蚀构件。通过对4种不同工况下混凝土中钢筋电化学加速锈蚀方法进行对比试验,得到了锈蚀后钢筋表面形态特征,分析了模拟自然环境条件下钢筋锈蚀的适用性。试验表明：全浸泡外加电流加速锈蚀方法使钢筋纵向、径向表面形成均匀锈蚀,而自然环境锈蚀钢筋表面锈蚀相对不均匀,坑蚀更明显,两者差异显著;利用全浸泡外加电流加速锈蚀方法进行锈蚀钢筋与混凝土粘结-滑移本构关系和锈蚀钢筋混凝土构件承载能力等研究不合适;半浸泡和贴面外加电流加速锈蚀方法能较好模拟自然环境锈蚀;加速锈蚀试验方法的理论锈蚀质量高于试验锈蚀质量。图12表1参7     

The use of inorganic conversion coatings to enhance the corrosion resistance of reinforcement and the bond strength at the rebar/concrete

The performance of concrete specimens reinforced with uncoated rebars or rebars coated with inorganic conversion coatings was investigated. The corrosion resistance of rebars and the bond strength at the rebar/concrete interface for uncoated rebars as well as rebars coated with three different inorganic conversion coatings were evaluated according to the corresponding ASTM G109 standard. The results showed that different inorganic conversion coatings give significant enhancements of corrosion resistance and increased interface bond strength compared to uncoated ordinary steel rebars. However the extent to which each conversion coating improves the corrosion resistance of the rebars and the interface bond strength inevitably depends on the chemical composition of the applied inorganic conversion coating.     

A Comparative Test Study of the Impact Performances of Stainless-Steel Rebar Equal-Strength Replacement Piers

It has been found that there are rebar instability and construction complexity phenomena associated with the replacements of ordinary pier rebars with stainless-steel rebars of equal piece numbers and strength. Therefore, this study explored the issues of the equal-strength replacements of stainless-steel pier rebars with different distributions. The study utilized the most advanced domestic multi-function super-high heavy hammer impact test system available, and conducted a comparative test of the horizontal impact results of two groups of pier models with 1/5 contraction scales. The purpose of the testing was to analyze the impact force, impact displacement, strain time history curve, crack propagation and distribution, ultrasonic damages to the concrete, and so on. The test results showed the following: The original specimen displayed a consistent variation trend with the equal replacement specimen of the stainless-steel rebar of different distributions from the aspects of the maximum impact force, strain of the rebar and concrete, displacement peak, and so on, under the conditions of continuous multiple impacts. The relative variation rate was found to be within the scope of ± 10% under equal impact energy. The quantity and distribution of the cracks, as well as the concrete damages, were also found to be approximately consistent under equal impact energy. Therefore, in this study, it was considered to be feasible for the solution of the problems related to rebar corrosion, strength surplus, resource waste, and so on, to replace ordinary pier rebars with stainless-steel rebars with equal-strength and different distributions.     

钢筋阻锈剂综述

混凝土中钢筋的腐蚀是钢筋混凝土建筑过早损坏的主要原因。阻锈剂是阻止钢筋混凝土腐蚀的主要手段之一,全面介绍了阻锈剂的性能、阻锈机理及检测手段。     

混凝土结构钢筋锈蚀耐久性损伤评估及寿命预测方法

对钢筋锈蚀耐久性损伤与构件承载能力可靠性等级的关系进行了分析，提出了混凝土结构中钢筋锈蚀耐久性寿命评估和预测方法，可为混凝土结构可靠性鉴定提供充分依据