钢-混凝土组合梁负弯矩区抗剪性能研究

Steel-concrete composite beams can give full play to the mechanical properties of steel and concrete, which are widely adopted in infrastructure in our country for its light weight, high carrying capacity, good dynamic performance, large span, high degree of assembly and excellent economic performance. However, existing researches do not clarify the composite shear mechanism of steel girder and concrete slab, and the calculation methods of shear capacity and design methods of web stiffeners are too conservative. In this study, theoretical analysis, model test and finite element method are used to study the shear capacity, moment-shear interaction and buckling of webs of steel-concrete composite beams under combined negative bending and shear with concerning the composite action of concrete slab and steel girder. This study will clarify the composite shear mechanism of steel beam and concrete slab and then propose the calculation methods of shear capacity under negative moment with concerning the contribution of the composite action. The negative moment-shear interaction mechanism of composite beams will be clarified, and then the negative moment-shear interaction curve will be obtained. Considering the rotational restraint effect of concrete slab, the calculation methods of critical buckling stress and shear buckling coefficient of steel girder web will be established, and then the design methods of stiffeners under negative moment will be proposed.

钢-混凝土组合梁能充分发挥钢与混凝土的材料性能优势，具有自重轻、承载能力高、动力性能好、跨越能力强、装配化程度高和经济指标好等优点，在我国基础设施建设中应用越来越广泛。本项目拟针对钢-混凝土组合梁负弯矩区抗剪承载力研究存在的混凝土板和钢梁组合抗剪机理不明确、规范抗剪承载力计算方法和腹板加劲肋设计方法偏保守等问题，采用理论分析、模型试验和有限元数值分析方法对考虑混凝土板和组合作用的负弯矩区截面抗剪承载力、负弯矩区弯剪相关承载力、弯剪复合作用下负弯矩区腹板的稳定性能进行系统的研究。揭示钢梁与混凝土板组合抗剪机理，提出考虑混凝土板和组合作用的负弯矩区截面抗剪承载力计算方法；明确负弯矩区弯剪耦合作用机理，得到弯剪相关曲线和提出弯剪相关承载力计算方法；建立考虑混凝土板约束作用的钢梁腹板屈曲临界应力和剪切屈曲系数的计算方法，提出负弯矩区钢梁腹板加劲肋的设计方法。

钢-混凝土组合梁能充分发挥钢与混凝土的材料性能优势，具有自重轻、承载能力高、动力性能好、跨越能力强、装配化程度高和经济指标好等优点，在我国基础设施建设中应用越来越广泛。本项目针对钢-混凝土组合梁负弯矩区抗剪承载力研究存在的混凝土板和钢梁组合抗剪机理不明确、规范抗剪承载力计算方法和腹板加劲肋设计方法偏保守等问题，采用理论分析、模型试验和有限元数值分析方法对考虑混凝土板和组合作用的负弯矩区截面抗剪承载力、负弯矩区弯剪相关承载力、弯剪复合作用下负弯矩区腹板的稳定性能进行了系统的研究。揭示了钢梁与混凝土板组合抗剪机理，提出了考虑混凝土板贡献的负弯矩区截面抗剪承载力计算方法；明确了负弯矩区弯剪耦合作用机理，得到了弯剪相关曲线和弯剪相关承载力计算方法；建立了考虑混凝土板贡献的钢梁腹板屈曲临界应力和剪切屈曲系数的计算方法。