Analysis On Temperature Stress Of Super-long Structures Considering The Effect Of Foundation Stiffness

Building is required not or less set expansion joint due to the need of its building function and aesthetic, which leads to that the expansion joint spacing of the structure is far more than the rules and regulations in our country about adjustable seam limits. For over-long concrete structure, stress and deformation caused by temperature variation is studied generally. In practical engineering, the measures are often used such as pre-stress and post-cast strip to solve temperature stress. However, it is generally presumed in the design that the upper structure is embedded in the fixed end, thus ignore the influence of foundation's actual stiffness on the performance of over-long concrete structure. If taken into account of the limited restraint stiffness of foundation, the structure in design will be more reasonable, its mechanical performance will be improved. Then the over-long structure will be more economical efficiency and security.This thesis presents the following aspects of research and the corresponding results with the aid of finite element software ABAQUS based on great amount of theoretical analysis.1. Compared with the result of the model based on embedded-fixed-end assumption, it has less temperature stress in the slab and less internal force in the bottom of the column bottom when considering the limited foundation stiffness. By changing foundation stiffness to regulate structure lateral stiffness is also a method to reduce temperature effect of over-long structure.2. The method according to the current pile foundation code and is used to calculate the horizontal stiffness and rotational stiffness of pile foundation. Compared with the calculation results, finite element method is used to simulate the pile soil interaction. The conclusion is that the result of finite element simulation has less error and it can be used in subsequent analysis on the temperature stress of over-long structure considering foundation stiffness. And the size of soil around the pile can be 50 times the diameter of the pile in the finite element simulation of pile foundation.3. Study the deformation and internal force distribution of over-long concrete structure under season temperature difference and analyze the factor influencing temperature stress of over-long concrete structure. Data shows that the structural lateral stiffness has a great influence on the effect of temperature and the positiveeffect of the height of the bottom floor to reduce the temperature stress should be considered in the structure design.4. Combining with a project- Taiping Depot D2 project of Suzhou rail transit line 2, this paper compares the long-term field monitoring data with the result from the finite element numerical simulation of this over-long structure and analyze the similarities and differences between them in the service stage. The analysis which takes into account of the concrete creep and transient shrinkage properties, the limited restraint stiffness of foundation, shows that the limited foundation stiffness for beneficial effects on the temperature stress of super-long structure can not be neglected.