Analysis On Mechanical Behaviors Of Concrete-filled Steel Tubular Tower Of Houhu Cable-stayed Bridge

Concrete-filled steel tube (CFST) is consisted of steel tube and concrete,which can make full use of the two materials' performance. The bearing capacity of concrete is improved by the effect of constraint from steel tube,and the existence of core concrete will make the steel tubular avoid having local buckling. With the rapid development and gradually improvement of transport infrastructure in China,the number of new bridges increases these years. The higher bearing capacity in structure is needed because of the longer span of bridge. The CFST members can improve the bearing capacity, simplify and accelerate the construction,reduce the number of equipments,so we can achieve the purpose of cost reduction. At present, CFST members have been extensively applied in the engineering of bridge, which are mainly applied to the rib of arch bridge, the tower of cable-stayed bridge and suspension bridge and so on.The middle tower of Houhu Bridge in Huangpi District of Wuhan uses the circle-end CFST. The mechanical behaviors of circular and the square CFST have been studied fully by domestic and international scholars, but there are few studies related to the mechanical behaviors of the circle-end CFST. According to the measured data in the process of monitoring for the construction of Houhu Bridge and the numerical simulation by finite element analysis,this article carries on the analysis of the mechanical behaviors of circle-end CFST.Firstly, this article introduces the emplaced scheme of the sensor, the measuring instrument and the load cases in the construction of Houhu Bridge's tower. According to the characteristic of construction in the cable-stayed bridge,the load cases are divided into axial compression case and eccentric compression case so as to analyze the mechanical behaviors of the circle-end CFST.Secondly, an ANSYS model of finite element analysis was established to simulate mechanical characteristic under different load cases in the process of the bridge's construction,and it is necessary to summarize change rule of stress in the circle-end CFST tower which is under axial compression and eccentric compression respectively. By extracting the stress data from measuring point and comparing the theoretical data with the measured data, the result proves that the theoretical data is consistent with the measured data.Lastly, the models of CFST tower whit different cross-section (circle-end double-limb, circle-end single-limb, rectangular ) are established, by imposing axial compression and eccentric compression, the mechanical behaviors are compared. By analyzing stress cloud and extracting the stress data of the characteristic section, the results reflected the advantages of the mechanical behaviors of the circle-end CFST with double-limb which was applied in Houhu bridge .In the analysis of the mechanical behaviors of circle-end CFST tower applied in Houhu cable-stayed bridge, the method of measured data in-site was combined with the theory of finite element analysis and the contrast of different tower with different cross-section,the results reflected the change rule of stress of circle-end CFST tower under axial compression case and eccentric compression case. In addition ,the most disadvantaged stress state of the structure was found out. Some measures are proposed to this kind of structure members basing on the results of the measured data and the theoretical analysis.