Static And Stability Analyses Of A CFST Tied Arch Bridge With Three Spans Self-anchored

The concrete filled steel tube (CFST) tied arch bridge, with such characteristics as beautiful shape, great bearing capacity, and strong spanning ability, has been widely used in traffic construction in our country recently. In all kinds of arch bridges, the CFST tied arch bridge with three spans self-anchored is a half through rigid frame tied arch bridge. Due to the fact that most horizontal thrust caused by the main arch can be balanced by stretching tie bars, the application of tied arch bridges may greatly reduce the engineering amount and construction cost of the lower part and the basis of the arch bridge in the plain area and soft foundation region. In the present thesis, a new tied arch bridge in Anhui province was selected as the research object, and several aspects of the work have been performed as follows:(1) By using the bridge analysis software Midas/Civil, a finite element model of bar system for the whole bridge was established, the overall analyses were conducted for the construction stage and the operation stage of the bridge, and the mechanical characteristics of this kind of bridge were presented. The numerical results obtained provide load data for partially finite element analysis.(2) Since the arch springing suffers from complex forces and which is not universal, it is necessary to make a space stress analysis for the related parts. By Midas/FEA this thesis built a 3D solid model for the bridge’s arch springing. The stress distribution of the arch springing was obtained quantitatively. The weak area of the arch springing was found subsequently. And the safety and rationality of the design were verified accordingly.(3) According to the four typical working conditions in this bridge, this thesis made the associated linear elastic stability analyses and geometric nonlinear stability analyses. The results show that the geometric nonlinear stability is lower than the linear elastic stability, but the difference between them is relatively small. In addition, the thesis discussed the influence of the different rise-span ratio, rib rigid, and arrangement of transverse braces on the stability coefficient of the bridge. The findings may provide some references for the stability design of this kind of bridges.