氯盐与荷载耦合作用下混凝土结构性能劣化相似性研究

发布时间：2018-03-20 10:01

本文选题：锈蚀混凝土结构　切入点：相似理论　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：混凝土结构耐久性不足已经给世界各国造成了巨大的经济损失和社会、环境影响。当今世界,引起混凝土结构耐久性不足、甚至破坏的原因有很多,如钢筋锈蚀、冻害以及侵蚀环境下的物理化学作用等,其中以钢筋锈蚀问题最为突出。钢筋锈蚀不仅会减小钢筋有效截面积和改变钢筋材料性能,还会导致钢筋混凝土之间的粘结性能发生退化,进而严重影响混凝土结构的承载能力。因此,研究锈蚀混凝土结构性能劣化规律,对准确评估在役结构耐久性以及全寿命预测具有重要的理论意义和实际意义。本文结合国内外已有研究成果,在国家自然科学基金项目"基于钢筋锈蚀耐久性的混凝土结构全寿命性能及设计理论研究(51378241)"的资助下对氯盐与荷载耦合作用下混凝土结构性能劣化的相似性进行了研究,主要的研究工作如下;(1)荷载作用下混凝土中氯离子侵蚀规律的研究。在Fick第二定律的基础上,考虑荷载与环境(温度、相对湿度)对氯离子扩散规律的影响,对Fick第二定律进行了修正。推导出混凝土结构氯离子一维扩散区域与二维扩散区域内钢筋初锈时间计算方法。相关内容可以为研究自然环境多因素耦合作用下氯离子扩散规律提供一个理论参考。(2)氯盐与荷载耦合作用下,混凝土构件内钢筋锈蚀率的相似模型研究。在法拉第锈蚀定律的基础上,分析已有腐蚀电流密度模型的优劣点,确定本文采用的腐蚀电流密度模型。当两种氯盐环境(自然环境与恒电流通电加速环境)与荷载耦合作用下的钢筋锈蚀率接近时假设二者相等,以钢筋锈蚀率为纽带,建立基于钢筋锈蚀率的时间相似模型。开展自然环境试验与恒电流通电加速试验,并以恒电流通电加速试验中通电160h的构件为例,求得两种氯盐环境与荷载耦合作用下构件同时达到4%钢筋锈蚀率的时间相似系数λ_(t,η_s)=0.025,利用λ_(t,η_s)的值求得自然环境试验构件的锈蚀时间为4a,与试验值(1400d)误差为4.29%。相关内容为预测自然环境下混凝土结构内钢筋锈蚀率提供一定的理论参考。(3)氯盐与荷载耦合作用下,混凝土构件内钢筋锈胀力的相似模型研究。分别利用厚壁圆筒模型以及极坐标法建立钢筋均匀锈胀力以及非均匀锈胀力计算模型,推导出钢筋锈胀力与锈蚀时间的关系模型。当两种氯盐环境(自然环境与恒电流通电加速环境)与荷载耦合作用下的钢筋锈胀力接近时假设二者相等,以钢筋锈胀力为纽带,建立基于钢筋锈胀力的时间相似模型。开展自然环境试验,并以恒电流通电加速试验中通电12h的构件为例,求得两种氯盐环境与荷载耦合作用下构件内钢筋锈胀力同时达到5.42MPa的时间相似系数λt,qr=0.178,利用λt,qr的值求得自然环境试验构件的锈蚀时间为2.136a。相关内容为预测自然环境下混凝土结构内钢筋锈胀力以及保护层锈胀开裂时间提供一定的理论参考。(4)氯盐与荷载耦合作用下,混凝土构件内锈蚀钢筋与混凝土之间粘结强度的相似模型研究。基于多轴应力状态下的Mohor-Coulomb强度破坏准则,求得混凝土构件粘结滑移破坏过程中4个临界状态(内裂状态、劈裂状态、极限状态和残余状态)的粘结强度。当两种氯盐环境(自然环境与恒电流通电加速环境)与荷载耦合作用下粘结强度接近时假设二者相等,以粘结强度为纽带,建立基于粘结强度的时间相似模型。以恒电流通电加速试验中通电12h的构件为例,求得两种氯盐环境与荷载耦合作用下构件内裂强度、劈裂强度、极限强度和残余强度分别同时达到4.25MPa、7.98MPa、9.13MPa 和 1.47MPa 的时间相似系数分别是 0.005、0.00511、0.00598 和 0.00545,并且利用时间相似系数的值求得自然环境试验构件的锈蚀时间分别为0.06a、0.0613a、0.0718a和0.0654a。相关内容为预测自然环境下混凝土结构内粘结强度提供一定的理论参考。
[Abstract]:Durability of concrete structures has caused tremendous economic losses and social and environmental impact to the world. In today's world, caused by the lack of durability of concrete structure, and many reasons of damage, such as corrosion, damage and erosion under the environment of physical and chemical effects, the steel corrosion is a prominent problem of steel corrosion. Not only can reduce the effective cross-sectional area of reinforcing steel and reinforced material properties, will also cause the bond performance of reinforced concrete between the degraded, and seriously influence the bearing capacity of the concrete structure. Therefore, the research of corroded concrete structure performance deterioration, the accurate evaluation has important theoretical significance and practical significance in the durability of existing structure and life forecast. This paper reviewed the existing research results, in the National Natural Science Fund Project "concrete based on durability of reinforcement corrosion Study on the structure of whole life performance and design theory (51378241) "supported by the similarity of chloride and load coupling properties degradation of concrete structures are studied, the main research work are as follows; (1) study on the erosion of chloride ions in concrete under load. Based on Fick's second law. Considering the load and environment (temperature, humidity) on the effects of chloride diffusion, the Fick's second law was amended. Derive the concrete structure of chloride ion diffusion region and one-dimensional two-dimensional calculation method of diffusion region of initial corrosion time of steel bar. The related content can provide a theoretical reference for the diffusion of chloride coupling factors study on the natural environment. (2) chloride and load coupling, research on similarity model of steel corrosion rate in concrete structures. Based on Faraday's law of corrosion on the analysis of the corrosion current The merits of density model, determine the corrosion current density model used in this paper. When the two kinds of chlorine salt environment (natural environment and constant current power acceleration environment) and steel corrosion loading rate is close to two when the assumptions are identical to the corrosion rate of steel as a link, Jian Liji on the steel corrosion rate time similarity model. Carry out natural environmental test and the constant current power and accelerated test, with the constant current power to accelerate the electricity 160H component test case, obtained two kinds of chlorine salt environment and load coupling component also reached 4% steel corrosion rate time similar coefficient _ (T, _s =0.025, by using lambda ETA) _ (T, n _s) value of the corrosion time obtained natural environmental test component is 4a, and the test value (1400d) error of 4.29%. related content for the prediction of the natural environment in the concrete structure corrosion rate to provide a theoretical reference. (3) chloride and load coupling By study, similar model in concrete structures reinforced expansive force are established. The uniform expansion force of reinforced by thick wall cylinder model and the polar coordinate method and non uniform expansion force calculation model, deduces the relation model of corroded expansion force and the corrosion time. When the two kinds of chlorine salt environment (natural environment and constant current power acceleration environment) and close to the reinforcing load coupling when assuming that the two are equal to the reinforcing ties, the establishment of corroded expansion force based on the similar model. The time of natural environmental test, and with the constant current power to accelerate the power 12h component test as an example the two component, chlorine salt environment and load coupling in the corroded expansion force and time to 5.42MPa similar coefficient of T, qr=0.178, using lambda T, QR obtained the natural environmental test component corrosion time is 2.136a. in the pre Provide a theoretical reference for measuring the natural environment in the concrete structure reinforcing and cracking time. (4) chloride and load coupling, of similar model bond strength between steel bar and concrete in reinforced concrete members. The multiaxial Mohor-Coulomb strength failure criterion based on the state. 4 critical state obtained concrete bond slip failure process (internal crack, split state, limit state and residual state) of the bond strength. When the two kinds of chlorine salt environment (natural environment and the constant current power and acceleration environment) close to the bond strength load coupling assumption two equal to bond the strength of ties, the establishment of similar model of bond strength based on time. With the constant current power to accelerate the electricity 12h component test case, obtained two kinds of component chloride environment and loading coupling in tensile strength , splitting strength, ultimate strength and residual strength were also reached 4.25MPa, 7.98MPa, 9.13MPa and 1.47MPa time similarity coefficient is 0.005,0.00511,0.00598 and 0.00545 respectively, and the similarity coefficient value is calculated using the time of natural environmental test rusting time were 0.06a, 0.0613a, 0.0718a and 0.0654a. related content for the prediction to provide a theoretical reference for concrete in the structure of bond strength under natural environment.

【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375

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