Analysis And Design Of Steel Arch-shape Pylon In Cable-stayed Brigde

With the rapid development of modern cities,the demand for the landscape of urban cable-stayed bridges is becoming more and more high.The steel arch-shape pylon is widely used because of its beautiful shape,energy saving,high efficiency and green environmental protection,but relative researchs in China are relatively few.The stress parameters,the overall stability,the local stability and the ultimate bearing capacity of the steel arch-shape pylon are the key issues in the design.Firstly,the applications and researchs status of steel pylons at home and abroad were elaborated,the stress characteristics and existing problems of arch steel bridge towers were sout out.Taking a project as the research background,the stress characteristics of the arch pylon under different loads were calculated and analyzed in order to clear the form and the position that needs to be focused on in the design.The analysis shows that the arch steel bridge tower has good mechanical performance and can meet the normal requirements.Then the influence of these parameters on the static and elastic stability of the tower were studied by adjusting the parameters,such as the section size of the pylon,the thickness of the pylon wall plate,the size of the crossbeam,the initial tension of the cable and the location of the anchorage zone of the bridge tower.The analysis shows that the section size of the pylon has a great influence on the stress of the pylon compared with the size of the crossbeam,the initial tension and the location of the anchorage zone.With the decrease of pylon section size,the stress of pylon increases obviously,and the change of section size is approximately inverse proportional to the stress change of pylon.At the same time,the stiffness change of the pylon caused by the section size and the thickness of the wall plate and the change of the pulling force of the cable have great influence on the elastic stability of the cable-stayed bridge,and the size of the crossbeam and the position of the anchorage zone have little influence on the stability of the cable-stayed bridge.In view of the local stability,the theory of stiffened compression plate was explained,and the calculation methods of stiffener according to deferent national codes were compared,then ABAQUS plate element models were esteblished to calculate the ultimate capacity.The results show that the stiffened plate with small relative bending degree could be regarded as the flat stiffened plate with initial geometrical imperfections and has post-buckling strength,the ultimate bearing capacity of which is close to the flat and could be calculated occording to warpage stability coefficient of the flat.The stiffened plate with large relative bending degree has much more reduction of ultimate bearing capacity,the warpage stability coefficient of the in-plane bendigng stiffened plate decreases linearly with the increase of the relative bending degree,and the warpage stability coefficient of the out-plane bending stiffened plate tends to a certain value with the increase of the relative bending degree.Finally,the ultimate bearing capacity of the pylon section was calculated by comparison and use of the steel bridge codes in various countries.Although there are some differences in the method,the differences of results are not obvious,and the results of the new standard calculation in China are most close to the finite element results.The design of the arch steel pylons should not only be in accordance with the requirements of the standard,but also consider its relative bending degree.By optimizing the design of the tower column in the case study,it still has good mechanical properties and improves the economy and efficiency of the cross section.