钢桁腹组合结构梁桥力学性能分析

发布时间：2018-06-29 03:36

本文选题：钢桁腹 + 组合梁桥　；参考：《东南大学》2015年硕士论文

【摘要】：本文以钢桁腹-混凝土组合梁为研究对象,对其基本力学性能、挠度计算理论、横截面剪滞效应及偏载效应等进行了系统的分析与研究工作,为钢桁腹-混凝土组合梁桥的推广应用提供理论基础。采用有限元方法对钢桁腹-混凝土组合梁的基本力学性能进行分析与研究。结果表明,在荷载作用下,钢桁腹-混凝土组合梁的变形不能忽略剪切变形的影响：钢桁腹-混凝土组合梁的截面弯矩主要由混凝土顶、底板承担,剪力则主要由钢桁腹杆的竖向分力承担。基于钢桁腹-混凝土组合梁的力学特性,结合换算薄壁箱梁法,推导了钢桁腹-混凝土组合梁的变形控制微分方程,并给出了典型边界条件与荷载工况下钢桁腹-混凝土组合梁挠度计算的理论公式；分析了宽跨比、悬翼比、宽高比等结构几何参数对理论公式的影响,给出了挠度理论公式的适用范围,并验证了该范围内理论公式的计算精度。对承受跨中集中荷载、两点对称荷载与均布荷载等三种典型荷载作用的钢桁腹-混凝土组合梁挠度进行了分析,并与有限元计算结果进行了比较分析,结果表明：本文推导的钢桁腹-混凝土组合梁挠度计算理论公式与有限元结果吻合较好,验证了本文假设的钢桁腹-混凝土组合梁理论计算模型的正确性与合理性。分析了三种典型荷载作用下的剪滞效应特点；比较了不同结构体系下钢桁腹-混凝土组合梁的剪滞效应。计算结果表明,简支钢桁腹-混凝土组合梁桥在全桥范围内,混凝土顶、底板横向正应力均呈现不均匀分布的现象,部分截面出现负剪滞现象,不包含节点的断面在支座附近的剪滞效应比较明显：连续钢桁腹-混凝土组合梁,在均布荷载作用下,近中支座附近截面的负剪滞效应十分突出,在设计时需十分重视。基于剪滞效应的分析结果,计算了钢桁腹-混凝土组合梁的有效分布宽度,并与规范计算结果进行了比较。结果表明,采用规范法计算简支钢桁腹-混凝土组合梁的有效宽度比较保守。分析了宽跨比、宽高比、翼厚比等结构几何参数对钢桁腹-混凝土组合梁剪滞系数的影响,结果表明：宽跨比对钢桁腹-混凝土组合梁剪滞系数具有较大的影响,而宽高比和翼厚比对剪滞系数的影响不大。对活载作用下钢桁腹-混凝土组合梁的正应力偏载效应进行了分析,结果表明,与普通混凝十箱梁相比,钢桁腹-混凝土组合梁的偏载效应显著,对此类梁进行抗扭设计时应对正应力偏载系数经验值适当放大。采用等效腹板法分析了钢桁腹-混凝土组合梁的偏载系数,并给出了等效板厚的计算公式,可为钢桁腹-混凝土组合梁的偏载效应研究提供参考。
[Abstract]:In this paper, the basic mechanical properties, deflection calculation theory, cross section shear lag effect and eccentric load effect of steel truss concrete composite beams are systematically analyzed and studied. It provides a theoretical basis for the popularization and application of steel truss-concrete composite beam bridge. The basic mechanical properties of steel truss-concrete composite beams are analyzed and studied by finite element method. The results show that the deformation of steel-truss belt-concrete composite beams can not ignore the influence of shear deformation under load: the cross-section bending moment of steel-truss belt-concrete composite beams is mainly borne by the concrete roof and the bottom slab. The shear force is mainly borne by the vertical force of the steel truss web member. Based on the mechanical properties of steel truss belt-concrete composite beam and the method of conversion thin-walled box girder, the deformation control differential equation of steel truss belt-concrete composite beam is derived. The theoretical formulas for deflection calculation of steel truss belt-concrete composite beams under typical boundary conditions and load conditions are given, and the effects of structural geometric parameters such as width to span ratio, hanging wing ratio and width to height ratio on the theoretical formula are analyzed. The application range of deflection theoretical formula is given, and the calculation accuracy of the theoretical formula in this range is verified. The deflection of steel truss below-concrete composite beams subjected to three typical loads, such as concentrated load, two-point symmetrical load and uniform load, is analyzed, and the results are compared with those of finite element method. The results show that the theoretical formula of deflection of steel truss concrete composite beams derived in this paper is in good agreement with the finite element results, which verifies the correctness and rationality of the theoretical calculation model of steel truss web concrete composite beams assumed in this paper. The characteristics of shear lag effect under three typical loads are analyzed, and the shear lag effects of steel truss belt-concrete composite beams under different structural systems are compared. The calculation results show that the transverse normal stress of the concrete roof and bottom slab of the simply supported steel truss belt-concrete composite girder bridge is unevenly distributed in the whole span of the bridge, and the negative shear lag occurs in some sections. The shear lag effect of the section without joints near the bearing is obvious: the negative shear lag effect near the middle support section is very prominent under the uniform distribution load of continuous steel truss belt-concrete composite beam, which should be paid more attention to in the design. Based on the analysis results of shear lag effect, the effective distribution width of steel truss concrete composite beams is calculated and compared with the calculated results of the code. The results show that the effective width of simply supported steel truss-concrete composite beams calculated by the code method is conservative. The effects of structural geometric parameters, such as width to span ratio, width to height ratio and wing to thickness ratio, on shear lag coefficient of steel truss web concrete composite beam are analyzed. The results show that the width span ratio has great influence on shear lag coefficient of steel truss web concrete composite beam. The ratio of width to height and the ratio of wing to thickness have little effect on the shear lag coefficient. The effect of normal stress deflection on steel truss web concrete composite beam under live load is analyzed. The results show that the deflection effect of steel truss web concrete composite beam is significant compared with that of common concrete box girder. The experimental value of normal stress deflection coefficient should be enlarged properly when torsional design of this kind of beam is carried out. The deflection load coefficient of steel truss belt-concrete composite beam is analyzed by using the equivalent web method, and the calculation formula of equivalent slab thickness is given, which can be used as a reference for the study of the deflection effect of steel truss belt-concrete composite beam.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441

【相似文献】