非概率可靠性算法研究及其在桥梁评估中的应用

Choosing simple-structural arch bridges and reinforced concrete girder bridges as research objects, the non-probabilistic reliability assessment on existing bridges based on interval model will be carried out. Firstly, adopting optimized search technology, a non-probabilistic reliability optimization search algorithm based on interval model will be created. By entering the relevant information of uncertain parameters , response capacity of the sample points will be calculated using ANSYS, and undetermined coefficient of the response surface will be calculated through FORTRAN program. Through FORTRAN program calling for optimization engine subroutine of MATLAB, the most likely failure point and non-probabilistic reliability index will be obtained to realize the seamless connection of analytical analysis and numerical calculation. Then, choosing existing bridges as specific research objects, the interval information will be obtained by field measurement and sampling test analysis combined with design drawings and built drawings. Adopting the proposed non-probabilistic reliability optimization search algorithm, non-probabilistic reliability assessment will be done on bridge structures and components. For security structures, the safety margin of vehicle load will be further determined. For unreliable structures, the maintenance and reinforcement program advices or warnings will be given. The research project can propose a conservative reliability assessment method with less information demanding and small computational effort for existing bridges. It can also provide technical support for bridge repair and reinforcement.

本项目以简单体系拱桥和钢筋混凝土梁桥为研究对象，实施基于区间模型的在役桥梁非概率可靠性评估。首先，采用优化搜索技术，创建一套基于区间模型的非概率可靠性优化搜索算法。通过输入不确定参数的相关信息，利用ANSYS计算样本点的响应量，FORTRAN程序计算响应面待定系数，通过FORTRAN程序调用MATLAB优化引擎子程序，求得最可能失效点和非概率可靠性指标，实现解析分析与数值计算的无缝连接。然后，以在役桥梁结构为具体研究对象，经现场测量和取样试验分析，结合设计图纸和竣工图纸获取区间信息，利用项目所确立的非概率可靠性优化搜索算法，对桥梁结构和构件进行非概率可靠性评估。对于安全结构，利用反优化设计进一步确定车辆荷载的安全裕度，对于不可靠结构，给出维修加固方案建议或预警。该项目研究可为在役桥梁提供信息需求量少、计算工作量小、结果偏于保守的可靠性评估方法，为桥梁维修加固提供技术支撑。

在参数信息匮乏的情况下，基于概率论与数理统计方法的传统可靠性理论在处理工程随机问题时有其局限性。然而，非概率可靠性理论无需知道具体的概率密度分布函数，只需知道参量的上下界就能求解非概率可靠性指标，对实际的结构进行可靠性评估，在工程中有着更广泛的适用性。.本基金创建了基于区间模型的非概率可靠性优化搜索算法，并以在役桥梁为研究对象，实施基于区间模型的在役桥梁非概率可靠性评估。具体的研究成果如下：.(1)对基于区间模型的结构非概率稳健性设计进行了优化。.(2)对在役桥梁进行了非概率可靠性评估，不安全情况下通过碳纤维布对桥梁进行加固，并对加固后的桥梁进行了可靠性评估。.(3)创建了基于区间模型的全局最优解法、改进的全局最优解法、改进的响应面法、简化的非概率响应面法和非概率响应面界限法。.(4)创建了基于非概率的在役桥梁可靠性评估流程，利用创建的算法对在役的5跨空腹式拱桥和3跨连续PC刚构桥分别进行可靠性评估。.(5)分析车辆模型因素对车桥耦合的影响，研究相同速度条件对跨中位移的影响情况,后期将进一步研究基于非概率理论的车桥耦合；研究了基于改进设备的钢桁梁顶推施工线形及应力控制，后期进一步研究施工期桥梁非概率可靠性评估。