Study And Application Of Non-abutment Slant-legged Rigid Frame Bridges

Non-abutment slant-legged rigid frame bridge is a new bridge type, which is widely applied in engineering practice, on account of its unique advantages in respect of adaptability, economy and landscaping, in recent years. However, the theoretical study lags behind. On the basis of engineering practice, this dissertation performs systematic and comprehensive study on a wide scope of this type of bridge, including typical non-abutment slant-legged rigid frame bridge, non-abutment slant-legged rigid frame bridge with hinge, non-abutment slant-legged rigid frame skew bridge, multi-span non-abutment slant-legged rigid frame bridge, as well as the parameterized plot system of non-abutment slant-legged rigid frame bridge. For typical non-abutment slant-legged rigid frame bridge, on the basis of 3D model analysis, this dissertation for the first time puts forward the feasible range of ratio of side-span to mid-span, inclination angle of bridge leg and the number and location of diaphragm, and makes analysis on loading conditions and stiffness of structure from the aspects of stress level and structural displacement. This dissertation also proposes the arch effect on structure produced by back filling, and makes quantitative analysis on this effect. The analysis shows that, back filling exerts significant arch effect of structure, which is approximately 10%. This conclusion will provide reference for structural design optimization, and also provide theoretic foundation for the selection on related parameters of embankment fills such as soil type, compaction degree etc. The causes of in-plain rotation of skew bridge have been analyzed, then the rotating-resist mechanism of non-abutment slant-legged rigid frame bridge has been put forward for the first time, and the calculation formula has also been deduced. The analysis of plain displacement of non-abutment slant-legged rigid frame bridge has been performed, which shows that, compared with other types of skew bridges, the non-abutment slant-legged rigid frame bridge, on account of its unique structure, can effectively restrict in-plain displacement, and thus can ensure the safety of structure. By taking Tongfu Bridge in Guangdong Province as an example, this dissertation for the first time makes systematic exploration on the hinge location of non-abutment slant-legged rigid frame bridge, feasible form of hinge as well as the feasible range of inclination angle of leg. This dissertation conducts the above analysis in detail in internal force and displacement of structure. The analysis shows that, the location of hinge, hinge form and inclination angle of leg will greatly affect the internal force distribution of structure, which will be carefully treated. Based on the practical projects, some problems in design and construction of non-abutment slant-legged rigid frame bridge are discussed in detail in the dissertation. On the basis of comprehensive summary on present status and development trend in domestic and abroad bridge CAD field, this dissertation performs systematic study on related key techniques in respect of parameterized plot system for non-abutment slant-legged rigid frame bridge, the development approach, technical innovation, as well as technical support for the popularization of this new and excellent bridge type. The research results of this dissertation can enrich the design theory of non-abutment slant-legged rigid frame bridge. It can also provide valuable reference for the engineering application of non-abutment slant-legged rigid frame bridge.