| The concrete-filled steel tube bridge tower is a new type of bridge tower structure that features lightweight construction,easy installation and remarkable economic and technical performance,and can meet the requirements of rapid construction with factory pre-fabrication and on-site assembly.For the construction of concrete-filled steel tubes for the bridge towers,the concrete in the tubes needed to be poured on site,and the wet work load was large.Different construction methods have a large impact on the deformation of pylons,which are difficult to install and locate.Therefore,in this paper,in combination with the Longlun River Bridge of the Hainan Tourism Expressway under construction,Midas/Civil Finite Element software is used to construct a simulation-analytic numerical model of the cable-free special-shaped cablestayed bridge,and the construction optimization technique of the concrete-filled steel tube special-shaped bridge tower is investigated as follows.Firstly,in this paper,we systematically summarize the segmentation,off-site transportation selection,and connection structure types of concrete-filled steel tube specialty bridge towers,and compare and analyze the impact of the three construction schemes on the stress and alignment of concrete-filled steel tube specialty bridge towers.A comprehensive consideration of technical aspects,construction period,cost,construction risk and construction control difficulties were taken into account to come up with the proposed construction plan.Secondly,based on the design and construction scheme of the original bridge tower,the construction optimization study of the concrete filled steel tube bridge tower was carried out.Midas/Civil,a finite element software for bridges,was used to construct a numerical model for the optimal analysis of the cantilever assembly construction with the tower adjusted from 19 segments to 13 segments and the full support construction with the tower adjusted to the cantilever assembly construction.Simulation analysis of the optimized construction process is performed.The results showed that the stress of the bridge tower during construction was dominated by the compressive stress of the steel pipe,with a maximum compressive stress of142.39 MPa.In the bridge phase,the maximum displacement of the tower top in the x,y,and z directions is 34.3 mm,-1.7 mm,and-5.6 mm,respectively.After the construction optimization,the stresses and deformations of the pylons meet the requirements of the code.Finally,considering the influence of earthquake on the bridge tower,a numerical analysis model is established for the uncombined and completed state of the bridge tower,and the dynamic performance analysis of the construction stage and completed state of the steel pipe concrete bridge tower is carried out.The Lanczos method was used to analyze the mode of the bridge tower,and its mode and natural frequency were obtained.Based on three kinds of seismic waves,the time-history analysis method is adopted to analyze the stress and displacement changes of concrete-filled steel tube bridge tower under the action of ground motion in the construction process and bridge formation stage.The results show that there is a certain difference in the displacement and stress generated at the same section of the bridge tower under different seismic waves.The seismic response of the unclosed bridge tower under EI-Centro wave is the largest in the construction stage,and that of the bridge tower under Taft wave is the largest in the bridge tower forming stage.Under the action of earthquake,the maximum displacement of the bridge tower in x,y and z directions is 110.3 mm,164.1 mm and 68.6 mm in the construction stage,and the maximum displacement in x,y and z directions is 81.0 mm,58.6 mm and 46.0 mm in the bridge formation stage.In the concrete filled steel tube bridge tower,the stress carried by the steel tube is larger,while that carried by the concrete is smaller.The maximum stress of the steel tube in the construction stage and the bridge completion stage is-69.8 MPa and-46.6 MPa respectively,both of which are compressive stresses,which all occur at the bottom of the tower # 3. |
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