考虑应力-锈胀开裂动态相互作用的钢筋混凝土构件耐久性劣化规律研究

For the reinforced concrete structures exposed to chloride environment, both of the steels' corrosion and its induced concrete’s cracking have an adverse effect on the serviceability and safety of the structure. A more accurate result can be developed when the interaction effects between stress and steel corrosion are simultaneously considered. To explore the degradation regulation of structures under loading and steel corrosion, corrosion test, theoretical analysis and numerical simulation will be adopted in this project. Firstly, loaded steel's corrosion under chloride environment will be developed based on the electrochemical corrosion. Then a model of corrosion-induced concrete cracking with longitudinal stress will be established to illustrate the relationship between crack width and corrosion rate. The durability deterioration process will be simulated by finite element analysis method which consider the interaction of stress, steel corrosion and concrete crack. reinforcement concrete beams under loading will be exposed to NaCl solution and 3d digital speckle technique will be used to monitor the strain of concrete. The results will be used to verify the correctness of model simulation. Finally, an actual degradation mechanism will be obtained for the flexural beam exposed in chloride environment. The expected results will help researchers get a more correct service life of loaded reinforced concrete specimen exposed in chloride environment.

对于氯盐环境下服役的钢筋混凝土构件，氯离子侵入混凝土造成的钢筋锈蚀、混凝土保护层开裂对结构的正常使用性能、承载能力有不利影响。开展荷载与腐蚀动态耦合作用下的钢筋混凝土构件耐久性研究可更为准确地把握结构的服役性能。本项目拟通过理论分析、室内试验及数值模拟，得出应力-锈胀开裂动态相互作用下钢筋混凝土构件的耐久性劣化规律。首先利用电化学腐蚀等理论建立氯盐侵蚀下受拉钢筋的锈蚀速率模型；然后利用假设的非均匀锈胀位移分布曲线，得出锈胀裂缝随钢筋锈蚀率的发展规律；利用扩展有限元方法及相关软件将钢筋锈蚀、混凝土开裂等过程整合在一起进行多物理场耦合分析；同时进行受荷钢筋混凝土构件在氯盐环境中的腐蚀试验，基于三维数字散斑技术实时监测构件的裂缝及应变，以此验证模型的正确性；最终得出受荷钢筋混凝土构件锈胀开裂过程中的实际劣化规律。预期成果有助于更加准确的预测氯盐环境中服役的钢筋混凝土构件的耐久性寿命。

本项目通过试验研究、数值模拟、理论分析等手段，重点研究了受荷混凝土内的氯离子传输、钢筋锈蚀特性，建立了相应的数学物理模型和数值模拟方法，并利用已有试验数据和课题组取得的试验数据进行了验证，得出了与试验数据吻合较好的结果。.主要研究成果有：1）考虑混凝土养护湿度及受弯混凝土内的应力分布影响，建立了氯离子扩散系数随混凝土养护湿度和应力水平的变化方程，由此得出了不同截面混凝土内氯离子的传输方程，并采用已有素混凝土和钢筋混凝土梁内的氯离子含量试验数据进行了验证；2）建立了受荷构件中的混凝土锈胀损伤演化模型；3）进行了受拉钢筋与纤维筋在氯盐环境中的腐蚀试验，初步得出了短期内钢筋腐蚀速率的变化规律，并与理论模型进行了对比，验证了理论模型的正确性。4）进行了氯盐干湿循环-弯曲荷载动态作用下混凝土的氯盐侵蚀试验，得出了两者动态作用下混凝土内的氯离子侵蚀及钢筋锈蚀规律。.通过此项目研究工作，课题组共培养了3位硕士；发表学术论文5篇，其中EI检索1篇；申请并获批实用新型专利1项。.