Experimental Study On The Stress And Bond-slip Performance Of Concrete-filled Steel Tubular Tower Of Suspension Bridge

Because of good plasticity and toughness, as well as high bearing capacity,concrete-filled steel tube structure is increasingly used in modern construction engineeringstructure, such as long-span bridges, high-rise building structure and so on.Liujiaxia suspension bridge adopts tower of concrete-filled steel tube structure, which is thefirst time in domestic that the tower of concrete-filled steel tube structure is applied in largespan suspension bridge. But the research on the stress and bond-slip performance is less,especially the research on the tower of concrete-filled steel tube structure in large span ofcable-stayed bridge and suspension bridge. Based on the theoretical calculation and thesection model test of Liujiaxia suspension bridge tower, the article mainly researches thestress condition of large-span suspension bridge tower using of the concrete-filled steel tubestructure in the actual construction conditions and operation process, and researches thebond-slip performance of large diameter steel tube concrete structure under larger verticalload and bending moment.Use the finite element software ANSYS for finite element simulation calculation, andaccording to the ratio of1:5produce compression test model and bond slip test model forLiujiaxia bridge tower top of section concrete filled steel tubular. In the summary of theresearch of domestic and foreign scholars on mechanical properties and the bond slipbehavior of concrete filled steel tubular structure, and combining with relevantcalculation theory of concrete filled steel tube structure and large-span suspension bridge,select the appropriate constitutive model of stress-strain relationship of steel tube and coreconcrete, then analyze the force situation of the suspension bridge tower model indifferent thickness of endplate, different size of cable saddle and different eccentric distanceof cable saddle.In the process of finite element simulation of concrete filled steel tubular structure ofsuspension bridge, referring to the existing research results of concrete filled steel tubularstructure, discuss the issues related to the finite element analysis of concrete filled steeltubular structures, such as selection of steel and concrete unit type and stressstrain constitutive model, meshing density, contact unit set, and convergence control. After,reasonably simulate the mechanical behavior of concrete filled steel tubular structures and thebond-slip performance of lateral steel tube and core concrete. On the basis of actual stressconditions about the CFST tower of Liujiaxia suspension bridge, including the force pushingthe cable saddle in the process of construction, respectively apply proportional loads to thesegment model of CFST tower at different eccentricity, to study the stress anddisplacement variation with load on segment model of CFST tower at axial and eccentriccompression and to study longitudinal stress and displacement variation characteristics at different thickness of endplate, at the same time, mechanical properties is studied about largediameter steel tube concrete bridge tower.According to the segment model test results of CFST tower of Liujiaxia suspension bridge,the bond stress is substantially exponential distributing along the bridge tower modellongitudinally. Compare the bond failure load and displacement of bond failure acquiredthrough the segment model test of CFST tower with nonlinear finite element calculationresults, we can find that the experimental data is greater than theoretical value, but thetheoretical value is regular in contrast. Analyze the reason that the theoretical value isdifferent with the test results, and generally the finite element calculation result is moreaccurate, reasonably simulating the force performance of suspension bridge in the process ofactual construction and operation. The study of compress and bond slipperformance of concrete filled steel tubular tower of Liujiaxia suspension bridge can providereference for the subsequent design and research of concrete filled steel tubular tower of longspan suspension bridge.