Yongxiu Large Frame Tied Arch Bridge Frame Arch Stability And Ultimate Analysis

The main bridge of Yongxiu super large bridge, located at Nanchang-Jiujiang inter-city railway, is a rigid-frame through tied-arch bridge with span arrangement of (31.75+128+31.75) m. It is the structural system, which has the following characteristics, such as arch-pier fixed, beam-pier separated, load mainly endured by the arch, beam only used for bearing load between joints and providing bridge deck system. The load between joints of the main girder is transferred by suspender to axial force of the arch. The vertical component force of the axial forces in arch foot is transferred by pier to foundation, while the horizontal component is balanced by tied bar.The bridge has the characteristics of wide span and the complexity in structure as well as in construction techniques. In order to conform tightly to the requirement of the design and construction of this project, combining with the final design and the construction blue print, the present thesis explores the stability and ultimate bearing capacity of rigid frame arch, finishing the following tasks:1. Based on energy method, this thesis deduces the analytical formulas of the lateral critical bucking load of the circular double-rib arch bridge in considering the leaning angle of arch ribs and the bending deformation capacity of transverse braces in the radial plane of arch rib. Then the analytical formulas are compared with other literatures.2. Introducing the concept of load distribution coefficient, single-wave symmetric and double-wave antisymmetric displacement function, based on ritz method, the present thesis deduces the analytical formulas of the lateral critical bucking load of the parabola parallel double-rib arch bridge with the orientedly conservative loadings, non-orientedly conservative loadings, consolidated support and hinged support, and compares with other literatures. Then it analyses the effect of some structure parameters on the lateral critical bucking load and non-orientedly conservative loadings of suspenders.3. The present thesis builds finite element model of Yongxiu rigid frame tied arch bridge. Based on linear elastic, geometric nonlinear and double nonlinear analysis methods, this thesis analyses the stability and ultimate bearing capacity of Yongxiu rigid frame tied arch bridge, studies on the effects of non-orientedly conservative loadings of the hanger and stiffness of piled foundation on the stability of the rigid frame arch, and verifies the stability and safety of structure design.4. Based on the results, the present thesis studies on the failure process and failure mechanism of rigid frame arch, discusses the effects of geometric nonlinear and double nonlinear on the stability and ultimate bearing capacity.5. Building the structure finite element model, the present thesis studies on the influences of rise-to-span ratio, the position, number and type of transverse Brace, initial geometric imperfection and material strength on theultimate bearing capacity of the rigid frame arch.