In-plane Bearing Capacity Of High-strength Concrete-filled Steel Tubular Arches

With the development and application of high-strength materials and the actual demand for light-weight long-span structures,high-strength steel tube-high-strength concrete composite structures emerge as the times require,such as HS-CFST arch.However,HS-CFST arch has a large slenderness and is mainly under compression.Stability is an important factor in control design.At present,there is little research on HSCFST arch,and there is no unified understanding of its mechanical properties and failure forms,and there is no design code to follow.Based on model test and finite element analysis,the in-plane elastic-plastic stability of HS-CFST arch is studied in this paper.The main contents are as follows:(1)The in-plane bearing capacity of HS-CFST parabolic arch is studied.In this paper,six parabolic arch rib specimens of high strength steel tube and high strength concrete with different strengths are designed and processed.Detailed loading schemes are formulated.Deformation and strain measurement points are arranged at each control section of the arch rib.The variation of internal force and deformation of the specimens during the whole loading process are tracked through five-point vertical symmetrical step loading,and the stress behavior of the arch rib under uniform load is proved.The ultimate bearing capacity and failure modes of HSCFST are obtained.It is found that the failure modes are closely related to the initial imperfections of arch ribs.(2)HS-CFST parabolic arch numerical analysis.The finite element calculation and analysis model of HSCFST parabolic arch is established by using ABAQUS software.The geometric nonlinearity,material nonlinearity,hoop effect of core concrete and initial geometric defects of the arch are fully considered.The load-displacement curve and load-strain curve of the arch during loading are obtained and compared with the experimental results.The analysis verifies the reliability of the experimental results and the accuracy of the finite element model.(3)A formula for calculating the in-plane stability bearing capacity of high-strength steel tube-high-strength concrete arch is proposed.Based on the experimental results and the analysis results of thousands of finite element model parameters,the effects of the strength,rise-span ratio,slenderness ratio and steel content of steel tube and concrete on the in-plane bearing capacity of the arch are analyzed.A formula for calculating the in-plane stability bearing capacity of the high-strength steel tube-high-strength concrete arch under full-span vertical uniform load is proposed.The formula is also applied to the stability design of the ordinary concrete filled steel tube arch.By contrast,the new formula takes into account the effects of rise-span ratio,steel tube strength and concrete strength.