Key Mechanical Properties Analysis And Research Of Concrete-filled Steel Tube Arch Bridge

Since the China’s first concrete-filled steel tube arch bridge was built in1990,for the next decades, the CFST arch bridge has developed rapidly. However, CFSTarch bridge theory failed to keep pace with the engineering practice. There was nospecific criterion for the design of CFST arch bridge now. This paper is based onGuangxi Laibin city Laihua bridge to make a study on the stability capacity and creepof CFST arch bridge, and the finite element software ANSYS is employed. The maincontents and conclusions are as follows:(1) The development and characteristics of CFST are introduced. The applicationtrends and design theory of CFST arch bridge are introduced. And make a detailedpresentation on the the FEM simulation method and construction stage simulation.The ANSYS model of Laihua bridge is established and the MIDAS model isestablished as a comparison.(2) The form and stiffness of transverse brace, the arrangement of transversebrace, stiffness of the bridge deck system, which are macro factors affecting thestability are based on the first category stability theory to analyze. Analysis resultsshow that the form and stiffness of transverse brace and the live load distribution havegreat impact on the stability. The stiffness of deck has less impact on the stability. Thestiffness of transverse brace has less impact on the stability without changing the form.For transverse brace, there is more effective through the rational layout and formatselection to improve the stability than increasing its stiffness. The factors are arch ribinitial imperfections, steel tube initial stress, which are micro factors affecting thestability are considered double nonlinear to analyze its ultimate bearing capacity.Analysis results show that rib initial imperfection have great impact on the stability.But, in the actual project imperfections can not exceed specification requirements.When the rib initial imperfection is smaller than specification limit, it has little effecton the stability capacity. Steel tube initial stress has little influence on the archcapacity, it can be ignored.(3) The cnstruction stage creep and operating period creep of Laihua bridge areanalyzed. Analysis results are compared with the measured data.The AEMM methodand ANSYS metal creep equation are used for creep analysis. The creep model of JTGD60-2004specification is used in ANSYS metal creep equation method. The creepmodels of JTG D60-2004,CEP-FIP (1990), CEP-FIP (1978) and EN1992-2 specification are used in AEMM method. Finally, the influence of concrete creep onthe arch capacity is analyzed. And the capacity which considered cnstruction stagecreep and operating period creep of Laihua bridge is analyzed. Analysis results showthat the various creep models deformation results are colse in cnstruction stage creepanalysis. It should be noticed that creep causes evident stress redistribution inoperating period. Creep and initial stress combined have little influence on the archcapacity. Their influence on the arch capacity increased slightly, when the rib existsinitial imperfection. But, the influence is still relatively small. The influence ofconcrete creep on the arch capacity can be ignored.