在化物环境中暴露于局部腐蚀的RC堆中的裂宽度的预测
Wei Shao1, Xiaoqing He2, Danda Shi1
1College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai 201306, China.
Materials (Basel, Switzerland)
|October 14, 2023
概括
一个新的模型预测了由于局部腐蚀而导致海洋钢筋混凝土 (RC) 堆中的裂. 结果详细说明了腐蚀深度,覆盖厚度和孔因子如何影响裂的启动和传播,这对结构完整性至关重要.
科学领域:
- 土木工程 土木工程是指土木工程.
- 材料科学 材料科学 材料科学
- 腐蚀工程 腐蚀工程
背景情况:
- 由于化物诱导的腐蚀,海洋环境对钢筋混凝土 (RC) 结构构成重大风险.
- 局部腐蚀,特别是坑,是RC堆过早故障的关键因素.
- 现有的模型往往简化了腐蚀模式,需要对局部场景进行更准确的预测.
研究的目的:
- 开发一种新的预测模型,用于局部化物腐蚀的RC堆中的裂纹发展.
- 在特定的腐蚀条件下调查裂的启动和传播机制.
- 分析关键参数对裂行为和结构完整性的影响.
主要方法:
- 利用一个离散的方法来解决腐蚀坑半径模型.
- 开发了一个裂延伸模型来模拟裂的启动和传播.
- 用于预测最大腐蚀程度的限制裂标准.
- 对关键裂延伸参数进行了灵敏度分析.
主要成果:
- 腐蚀坑半径,深度和强化面积损失随着腐蚀水平的增加而增加.
- 裂纹启动强化损失受到混凝土盖对直径的比率和插孔因子的影响.
- 裂所需的坑深度随着混凝土覆盖厚度的增加而增加.
- 增强面积损失和坑半径与初始铁杆直径正相关.
- 较高的插孔因子降低了坑洞深度,但加速了裂宽度的发展;覆盖厚度增加提高了裂传播阻力.
结论:
- 开发的模型准确地捕捉了RC堆中的局部腐蚀下的裂发展.
- 局部腐蚀模式与海洋工程实践高度相关.
- 参数灵敏度分析为设计耐用的海洋RC结构提供了关键的见解.
相关概念视频
01:27Corrosion of Reinforcement
208
The corrosion of steel reinforcement within concrete is a process influenced by the material's inherent properties and external factors. The high pH level of around 13, provided by calcium hydroxide present in concrete, initially protects the steel reinforcement by promoting the formation of a passive iron oxide layer on its surface.
However, over time and under certain conditions like carbonation, chloride ingress, and cracking this protective state can be compromised. Steel has areas with...
However, over time and under certain conditions like carbonation, chloride ingress, and cracking this protective state can be compromised. Steel has areas with...
208
01:20Microcracking in Concrete
129
Microcracking in concrete refers to the tiny cracks that can form within the material even before any external load is applied. These microcracks typically occur at the interface between the coarse aggregate and the hydrated cement paste, often as a result of differential volume changes prompted by variations in stress-strain behavior, as well as thermal and moisture movement. Initially, these microcracks remain stable and do not grow substantially until the concrete is stressed to about 30...
129
01:25Effects of Creep
161
Creep in concrete, the gradual deformation under prolonged stress, significantly impacts the integrity of structures. For reinforced concrete beams, it can be a vital design consideration, as it increases deflection, sometimes necessitating additional design measures. In columns, especially slender ones under eccentric loads, creep can cause buckling, compromising their stability. However, creep can be beneficial in indeterminate structures by mitigating stresses that arise from shrinkage,...
161
01:28Types of Non-structural Cracks in Concrete
168
Non-structural cracks are primarily of three types: plastic, early-age thermal, and drying shrinkage cracks. Plastic cracks are further classified into plastic shrinkage cracks and plastic settlement cracks.
Plastic shrinkage cracks typically form within hours after the concrete is poured. The concrete's surface dries faster than the bottom, creating tensile stress that the still-plastic concrete cannot withstand, leading to diagonal or randomly patterned cracks on the concrete surface.
Plastic shrinkage cracks typically form within hours after the concrete is poured. The concrete's surface dries faster than the bottom, creating tensile stress that the still-plastic concrete cannot withstand, leading to diagonal or randomly patterned cracks on the concrete surface.
168
01:22Effect of Sea Water on Concrete
257
Concrete exposed to seawater can undergo degradation like the dissolution of ettringite and gypsum, increasing the material's porosity and decreasing its strength. In contrast, the crystallization of salts within the concrete's pores can cause expansion, particularly above the waterline where evaporation occurs. Nonetheless, this expansion only happens when seawater, enabled by the concrete's permeability, manages to infiltrate the structure.
Concrete in areas between tide marks,...
Concrete in areas between tide marks,...
257
01:16Tensile Strength Considerations of Concrete
135
Considering the tensile strength of concrete involves recognizing that the theoretical strength of cement paste can be up to a thousand times higher than what is observed in practical applications. This significant discrepancy is largely attributed to the presence of microscopic cracks within the concrete. These cracks tend to amplify stress at their tips when a load is applied, a phenomenon explained by Griffith's theory of brittle fracture.
The dimensions and shape of a concrete specimen...
The dimensions and shape of a concrete specimen...
135