PBL节点初始平动刚度计算及设计参数优化

为研究钢桁腹混凝土组合箱梁中PBL(Perfobond Leiste)节点的初始平动刚度及其影响因素,首先基于组件法,运用卡氏第二定理推导出考虑了开孔钢板与混凝土间的界面剪切力和混凝土榫贡献的PBL节点的初始平动刚度表达式,其次以某工程实例为背景,结合有限元模型验证所推公式的合理性;在此基础上分析了混凝土强度、腹杆直径、腹杆壁厚、开孔钢板开孔孔径和开孔钢板厚度等构造参数对初始平动刚度的影响,并利用正交分析法对以上5个参数进行优化组合。研究结果表明,本文方法计算的PBL节点初始平动刚度结果与有限元计算结果间的误差在8.0%以内;相较运用解三角形计算腹杆平动位移的方法,采用卡氏第二定理不仅可以简化计算,还可以减小解三角形过程中因多次计算变形带来的误差累积;腹杆刚度对PBL节点整体平动刚度的贡献最大,可达到82.5%;保持原设中的混凝土强度不变,将腹杆直径增加20 mm,将钢腹杆壁厚增加4 mm,将开孔钢板开孔孔径增加4 mm,将开孔钢板厚度增加4 mm,可以将PBL节点理论初始平动刚度提高约25.7%。

Calculation of initial translational stiffness of PBL node and optimization of design parameters

In order to study the initial translational stiffness and its influencing factors of the PBL (Perfobond Leiste) node in the steel-truss-web-concrete composite box girder,firstly,based on the component method,the second theorem of Karnife was used to derive that the interface shear force between the steel plate and the concrete.The initial translational stiffness expression of the PBL node contributed by falcon,followed by an engineering example as a background,combined with the finite element model to verify the rationality of the formula;on this basis,effects of the concrete strength,web member diameter,and web member wall thickness are analyzed.The influence of structural parameters such as the hole diameter and the thickness of the holed steel plate on the initial translational stiffness is analysed,and the orthogonal analysis method is used to optimize the combination of the above five parameters.The research results show that the error between the initial translational stiffness of the PBL node calculated by the method proposed in this paper and the finite element calculation is within 8.0%;compared with the method of calculating the translational displacement of the web member by solving the triangle,the second theorem is used.Not only can the calculation be simplified,but also can the accumulation of errors caused by multiple calculation deformations in the process of solving the triangle be reduced;the stiffness of the web members contributes the most to the overall translational stiffness of the PBL node,which can reach 82.5%;the strength of the concrete in the original design is kept unchanged,increasing the web rod diameter by 20 mm,the steel web rod wall thickness by 4mm,the perforated plate hole diameter by 4 mm,and the perforated steel plate thickness by 4mm can increase the theoretical initial translational stiffness of the PBL node by about 25.7%.