钢桁腹-混凝土组合梁等效计算模型及自振频率研究

EQUIVALENT CALCULATION MODEL AND NATURAL VIBRATION FREQUENCY OF COMPOSITE GIRDER WITH STEEL TRUSS WEBS

为分析钢桁腹-混凝土组合梁这种非连续腹板结构的力学性能,基于结构等效的理念,考虑钢桁腹杆结构在不同方向上的有效弹性模量,将不连续的钢桁腹杆梁腹结构等效为正交异性板梁腹结构;运用薄壁箱梁的弯曲振动和扭转振动频率公式,可计算出钢桁腹-混凝土组合梁的弯曲振动频率和扭转振动频率,并对有限元计算结果与理论公式计算得到的理论解进行对比分析,讨论了横向刚度对有限元求解方法和理论求解方法结果产生的影响;分析组合梁高度、钢桁腹杆截面积、悬臂端长度等结构尺寸因素对钢桁腹-混凝土组合梁自振频率的影响。结果表明,利用等效原理计算钢桁腹-混凝土组合梁自振频率误差在10%以内,具有较高精度,可为工程实践提供一定的理论依据;在顶底板结构尺寸保持不变的情况下,弯曲振动频率受其他结构参数影响的变化很小,扭转振动频率受钢桁腹杆截面积、悬臂端长度的影响变化明显,随着钢桁腹杆截面积的增大而增大,随着悬臂端长度的增大而降低。

In order to analyze the mechanical properties of the discontinuous web structure,based on the concept of structural equivalence and considering the effective elastic modulus of the steel truss web structure in different directions,the discontinuous steel truss web girder structure is equivalent to the orthotropic plate girder structure.Using thin-wall box girder bending vibration and torsional vibration frequency formula,can calculate the bending vibration frequency and torsional vibration frequency of composite girder with steel truss webs,and the finite element calculation results and the theoretical formula to calculate the theoretical solution were analyzed,discussed the lateral stiffness of the finite element method and the method of theory,the result of influence;The effects of structural dimension factors,such as the height of composite girder,the section area of steel girders and the length of cantilever ends,on the natural vibration frequency of steel girder-concrete composite beams are analyzed.The results show that the error of natural vibration frequency of composite girder with steel truss webs calculated by equivalent principle is within 10%,which has high precision and can provide certain theoretical basis for engineering practice.Under the condition that the structure size of top and bottom remains unchanged,the bending vibration frequency changes little under the influence of other structural parameters,while the torsional vibration frequency changes obviously under the influence of the section area and the length of the cantilever end of the steel truss,which increases with the increase of the section area of the steel girder and decreases with the increase of the length of the cantilever end.