酸雨环境腐蚀下钢管混凝土构件抗震性能研究

Concrete filled with steel tubular structures, as a new kind of composite structures which fully come into respective load characteristics of the steel and concrete, have been widely used. Over the service period of concrete filled with steel tubular structures, they usually not only bear occupancy loads such as vehicles, engineering machineary, etc and natural loads such as wind, waves, snow, earthquakes and so on, but sometimes also encounter such corrosion conditions as atomosperic environmen, marine envronment, industrial acid salt envireonment. China is not only an earthquake-prone area but also a acid- rain-frequent area. Therefore, the study on the seismic properties of concrete filled with steel tubular members under acid rain attack has great academic value and practical significance in improving the safety and durability of concrete filled with steel tubular members. In prsent application program, concrete filled with steel tubular members are used as the object of study. Proper test parameters to simulate acid rain environment are first selected. Consequently, a stress-strain constitutive relation considering corrosion damage evolution of durability for concrete filled with steel tubular members is constructed by using rapid acid rain corrosion test and damage mechanics method. In conjunction with numerical method of finite elements and seismic tests to simulate the earthquake response process of concrete filled with steel tubular structures, the mechanical behavior of the structures are investigated. The position for stress and plastic deformation concentration is examined to identify the yield mechanism of the structures. The hysteretic characteristics of moment-curvature and load-displacement are studied, and thus a simplified formulation for ductility factor as well as a hysteretic model are derived. Present research achievements will lay a theoretical and experimental foundation for the evaluation seismic performance and seismic design of concrete filled with steel tubular members.

钢管混凝土结构作为一种新型组合结构，充分发挥了钢结构与混凝土的各自受力特性，因而得到了广泛应用。钢管混凝土构件在服役过程中，不但要承受车辆、设备等使用荷载和大风大浪、冰雪、地震等自然荷载，有时还要遇到大气、海洋、酸碱盐等环境腐蚀。中国既是地震多发区，又是酸雨频现区，因此研究酸雨环境腐蚀下钢管混凝土构件的抗震性能，对提高钢管混凝土结构的耐久性和安全性具有重要的学术价值和实践指导意义。 项目以钢管混凝土构件为研究对象，选取合适的酸雨模拟参数，通过快速酸雨腐蚀试验和损伤力学方法，建立考虑耐久性腐蚀损伤的钢管混凝土应力-应变关系，配合抗震试验和数值分析模拟酸雨地区钢管混凝土结构的地震反应过程，得出构件受力形式；研究应力和塑性变形集中的部位，继而判明结构屈服机制，研究构件弯矩-曲率和载荷-位移滞回关系特征，延性系数，得到其恢复力模型，为酸雨地区钢管混凝土结构抗震性能评估和抗震设计奠定理论和试验基础。

本项目运用环境化学和现代力学相结合的新思维以及现代测试及有限元数值模拟技术，从源头上对钢管混凝土钢管外表面酸雨腐蚀损伤的微观表现与钢管混凝土构件宏观力学性能进行系统的研究，从本质上建立起其微观与宏观之间的有机关系，揭示酸雨环境和地震荷载共同作用下钢管混凝土构件抗震性能劣化机理，并建立恢复力模型。研究过程中主要有以下成果：（1）对传统的卧式装置进行了改进与创新，提供了一种结构简单，操作方便，少占试验空间对试验设备要求低的试验装置,并申请及授权多个相应的实验装置；（2）利用傅里叶函数的原理结合江西省酸雨监测站观测资料建立江西酸雨频率和pH值的数学模型，依据损伤力学定义，建立描述钢管外表面酸雨腐蚀损伤模型；通过系列试验数据建立腐蚀低碳钢的弹性模量，屈服强度，极限强度和伸长率等力学性能的线性表达式；（3）应用弹性力学理论和钢管混凝土柱协同工作条件,推导出了钢管混凝土柱组合轴压弹性模量和轴向压力分配的理论计算公式，考察了混凝土强度等级和含钢率对混凝土轴向压力分配系数、钢管混凝土柱组合弹性模量的影响。采用钢管壁厚和钢管刚度折减法，建立了钢管混凝土柱的锈蚀模型。并建立模拟酸雨溶液腐蚀后方、圆钢管混凝土构件的有限元模型，最终导出了酸雨腐蚀后钢管混凝土构件极限承载力简化计算公式。（4）利用ABAQUS商用软件，建立了往复荷载下酸雨腐蚀后圆钢管混凝土柱抗震性能的有限元数值模拟模型，并分析了轴压比和锈蚀程度对试件抗震性能的影响，（5）对项目进行深化研究，建立了腐蚀钢管混凝土柱时变可靠度的分析方法，研究了腐蚀钢管再生混凝土压弯性能。本项目有关模拟酸雨腐蚀钢管混凝土柱抗震性能的试验与有限元分析的研究结果，对酸雨环境腐蚀下钢管混凝土构件的抗震性能评估、优化设计、养护、维修和加固具有重要价值。研究工作达到预期目标，共发表论文67篇，其中SCI、EI论文10篇，申请专利6项，已授权4项，登记软件著作权4项。