考虑空间变异性的预应力混凝土梁桥长期变形谱研究

Due to the shrinkage and creep effect of concrete, long-term deformation of prestressed concrete bridge would be beyond the limit of buckles in non-ballasted track, in rail bridge. It would harm the smooth of tracks, and influence driving safety. Owing to the randomness of shrinkage and creep of concrete, random analysis method should be adopted to give a meaningful result with probabilistic guarantee. In the application, spatial random variability of bridge would be considered to predict more accurately the effect and statistics characteristic of shrinkage and creep by response surface method combining with Monte Carlo sampling. First, using Monte Carlo sampling combining with the HDMR(High Dimensional Model Representation) method, stochastic finite element model of shrinkage and creep would be presented, in which random field theory is employed to represent the spatial variability mentioned above. Then, the usual forms of rail bridge are chosen as research objects in the application. Correlation lengths of random parameters will be compared with the experimental data. What's more, parameters analysis and sensitive analysis will be carried out to find the key factors of long-term deformation, and to refine general rules. Finally, the method for long term deflection specturm of PC bridge will be researched.

混凝土的收缩徐变可能导致采用无砟轨道的铁路桥梁长期变形超出轨道扣件允许的调整范围，对轨道平顺产生危害，影响行车安全。为得到有概率保证意义的桥梁长期变形预测结果，需开展收缩徐变随机分析。项目认为桥梁模型参数在空间分布上具有变异性，该效应将影响随机分析结果。项目拟采用响应面结合蒙特卡洛抽样技术，预测混凝土桥梁的长期变形效应及概率特性。项目拟开展以下研究：（1）利用随机场理论描述桥梁模型参数的空间变异性，采用HDMR技术与MC抽样结合的方法，建立长期变形随机分析有限元模型；（2）以常用结构形式为研究对象，利用桥梁检测与试验的长期变形数据，开展随机参数相关长度的比较研究；（3）基于以上成果，项目将系统开展预应力混凝土桥梁随机变形的参数分析，通过敏感性分析研究参数对长期变形的贡献，找出关键因素，从中提炼具有普遍意义的规律和结论。最后，研究桥梁长期变形谱计算方法，得到预应力混凝土梁桥的长期变形谱。

该项目利用结合响应面方法与蒙特卡洛抽样技术的混合随机分析方法与自主开发的钢筋混凝土非线性有限元软件，实现了混凝土结构（包括预应力混凝土梁桥）的长期变形随机有限元计算方法；提出了分片响应面的分析方法，解决了混凝土结构开裂非线性引发的响应面不光滑问题；在大跨度预应力混凝土梁桥，大跨度钢筋混凝土劲性骨架混凝土拱桥中，开展了随机参数空间效应的测试，统计与理论分析工作，得到了相关长度的合理取值方法与评价标准；总结了混凝土基本构件（梁，柱）与大型桥梁结构的随机分析结果，提出了影响其长期变形的控制因素与施工控制方法。在本项目的资助下，发表学术论文11篇，其中SCI检索5篇，EI检索11篇；出版专著1部。