带加劲肋钢-混凝土组合蜂窝梁开孔腹板的抗剪性能

Shearing Performance of Perforated Web in Steel-concrete Composite Castellated Beam with Reinforced Webs

带加劲肋钢-混凝土组合蜂窝梁腹板成排开孔后,主要削弱了其抗剪稳定性和抗剪强度。为探明这一新型桥梁结构的力学特点,采用有限元方法对钢-混凝土组合蜂窝梁开孔腹板的抗剪性能进行了深入研究。对不同边界条件下的开孔腹板进行弹性剪切屈曲分析,考虑孔洞的影响引入径高比和宽高比参数,对实腹板剪切屈曲系数加以修正,并引入约束系数表征约束程度,推导得到了开孔腹板剪切屈曲系数的计算公式。建立开孔腹板抗剪极限承载能力有限元计算模型,考虑材料、几何双重非线性,对不同参数开孔腹板的抗剪承载能力进行了大量的有限元分析,在数据分析基础上量化弹性屈曲荷载和屈曲后荷载对开孔腹板抗剪承载能力的贡献。引入腹板的开孔率参数,提出了开孔腹板抗剪极限承载力的计算公式,同时分析了不同初始几何缺陷对开孔腹板抗剪性能的影响。结果表明:不同边界条件下的开孔腹板剪切屈曲系数公式与有限元值吻合良好;开孔腹板仍可发展一部分屈曲后强度,屈曲后强度可偏保守地表示为开孔腹板塑性强度的30%,开孔腹板抗剪极限承载力计算公式与有限元计算结果吻合较好,且总体偏于安全;不同的初始几何缺陷对开孔腹板荷载-位移曲线形式有较大影响,但对其抗剪承载能力影响很小。

The appearance of perforated web reduced the shearing stability and shearing resistance of steelconcrete composite castellated beam with reinforced webs（ SCCCB）. In order to investigate the mechanical characteristics of this new type of bridge structure,detailed study on shearing performance of perforated web in SCCCB is carried out by adopting finite element method. The elastic shear bucklings of perforated web under different boundary conditions are analysed. Considering the influence of holes and introducing parameters of aspect ratio,diameter-height ratio,and restraint coefficient of ordinary web is modified,constraint coefficient is introduced to describe the degree of constraint,and the formulas for calculating shear buckling coefficient of perforated web are derived. The finite element model is also built to calculate the ultimate shearing resistance of perforated web,a significant amount of analysis on the shearing resistance is executed considering material and geometrical nonlinearly,the contribution of elastic buckling load and postbuckling load to the shearing resistance of perforated web are quantified on the basis of data analysis. Then,a parameter of perforating ratio of the web is also defined,and the formula to evaluate the ultimate shearing resistance of perforated web is suggested,and the influence of different initial geometrical imperfections on shearing performance of perforated web is discussed. The result shows that（ 1） the proposed shear buckling coefficient formulas are coincident with the FEM result;（ 2） the perforated web still has some post-buckling strength,which can be valued conservatively as 30% of plastic strength of perforated web,the formulas for calculating shearing resistance of perforated web are in good agreement with the finite element method,and the results are conservative;（ 3） different initial geometrical imperfections have great effects on loaddisplacement relationship of perforated web,but little on its shearing resistance.