寒区近海混凝土桥梁性能衰退机理与损伤行为评估方法

受到周期性潮汐变化的影响,中国寒区近海混凝土桥梁长期遭受海水冻融及多种耦合腐蚀作用,这严重影响了桥梁的服役性能与使用寿命.为了准确预测桥梁的性能衰退规律,针对桥梁所处环境,分析了桥梁结构的性能退化机理,并借助近场动力学方法在多尺度方面的优势,利用MAT-LAB-ABAQUS联合仿真方法建立了桥梁劣化损伤预测与评估方法....

Performance Degradation Mechanism and Damage Behavior Evaluation Method of Concrete Bridge in Cold Region Marine Environment

Due to the influence of periodic tidal changes, offshore concrete bridges in cold regions of China have long been subjected to seawater freeze-thaw cycles (FTCs) and multiple coupling corrosion, which seriously affects the service performance and service life of bridges. In order to accurately predict the performance degradation law of the bridge, the performance degradation mechanism of the bridge structure was obtained according to the environment of the bridge. With the advantages of Peri Dynamics method in multi-scale aspects, the MATLAB-ABAQUS co-simulation method was used to establish the bridge deterioration damage prediction and evaluation method. On this basis, starting from the FTCs damage of concrete, considering the temperature distribution characteristics, the critical saturation model, the pore crystallization law and the pore pressure theory, the numerical simulation method of concrete under FTCs from micro-scale was established by pore deformation loading. Subsequently, according to the calculation results of concrete micro-scale FTCs damage, the equivalent numerical simulation method of RC pier considering FTCs damage distribution was established. Finally, the section of RC bridge pier was designed and manufactured, and the FTCs test of RC bridge pier in seawater environment was carried out. The FTCs damage distribution of RC bridge pier in seawater was obtained by using ultrasonic tomography technology. The test and calculation results show that the micro-scale calculation model of concrete can well simulate the FTCs damage behavior of concrete caused by pore accumulation and pore transformation during the FTCs by comparing with the results of ultrasonic tomography. Under the influence of temperature distribution and relative saturation, when the FTCs were greater than 50, the specimen had obvious FTCs damage boundaries (FTCs depth), and with the increase of FTCs, the growth rate of FTCs depth first increased and then decreased. In addition, the calculation results of the hysteresis curve of the equivalent calculation model are in good agreement with the experimental results. With the increase of the number of FTCs, the peak load of RC piers gradually decreases, and the influence of seawater FTCs on the mechanical properties of RC piers is very serious. The established calculation method well predicts the degradation of mechanical properties of RC piers under seawater FTCs.