考虑脱空缺陷影响的钢管混凝土压弯剪力学性能分析与实用设计方法

Analytical Behavior and Simplified Method of Concrete-Filled Steel Tube with Gap Under Combined Compression-Bending-Shear Actions

完成了12根带脱空缺陷的钢管混凝土试件在压弯剪复合作用下的滞回试验,考察了脱空缺陷对试件破坏模态、滞回曲线、极限承载力、耗能和延性的影响。建立了带脱空缺陷的钢管混凝土压弯剪试件的有限元分析模型,采用试验数据验证了有限元模型的可靠性。利用有限元模型分析了带脱空缺陷的钢管混凝土试件在压弯剪复杂受力作用下的工作机理,揭示了缺陷对钢管与混凝土之间相互作用的影响规律,并系统分析了含钢率、钢材屈服强度、剪跨比、轴压比和混凝土强度等参数对带缺陷试件抗剪承载力的影响规律。在参数分析的基础上,提出了用于区分试件剪切破坏和弯曲破坏的界限剪跨比,回归了考虑脱空缺陷影响的钢管混凝土压弯剪承载力实用计算公式,可为相关规范的制定或修订提供依据。

Under combined compression-bending-shear loading,12 concrete-filled steel tubular(CFST) specimens with a circumferential gap are subjected to cyclic tests,and the effects of gap on failure mode,hysteretic curve,ultimate bearing capacity,energy dissipation,and ductility of CFST specimens are investigated. A finite element analysis model of CFST specimens with a gap is developed,and the experimental results verify the model’s dependability. On the basis of the finite element model,the working mechanism of CFST specimens with a gap under combined compression-bending-shear loading is examined,as well as the effect of the gap on the interaction between steel tubes and concrete. On the shear capacity of specimens,many characteristics(such as steel ratio,steel strength,shear-span ratio,axial compression ratio,and concrete strength) are comprehensively examined. On the basis of parameter analysis,the limit shear-span ratio of CFST specimens used to differentiate between shear failure and bending failure is suggested. The realistic formula for shear capacity of CFST under combined compression-bending-shear stress is developed,providing a foundation for the creation or amendment of relevant standards.