平行钢丝索股的非线性弯曲特性研究
发布时间：2018-11-19 19:41
【摘要】：悬索桥主缆索股由大量离散的平行钢丝组成,其受力特性与均质一体材料形成的整体截面有较大的差异,尤其当索股截面受到弯曲作用时,同一截面的钢丝可能产生滑移,此时截面变形将不再满足平截面假定、弯曲应力的计算需借助复杂的非线性有限元计算方法。本文以拉弯力共同作用下的平行钢丝索股为研究对象,考虑索股分层、分阶段滑移的实际情况,建立了拉弯力共同作用下的平行钢丝索股的力学特性分析方法,并通过与试验和非线性有限元计算结果对比,建立了简化的平行钢丝索股非线性弯曲计算方法。论文主要研究内容如下:拉索弯曲的梁理论计算的弯曲应力会偏大的主要原因是没有考虑钢丝之间的滑移。对于有钢丝滑移的拉索,采用分段研究的思想,认为在相邻的两层钢丝初滑移转角之间截面惯性矩保持为不变,推导拉索弯曲曲率的变化与截面转角的关系,给出沿拉索轴向单位长度的弯曲剪切力计算公式。在物理方程关系的基础上,将索股的应变、应力与内力分解为线性项和非线性项,推导内力与变形关系的切线刚度矩阵,得出弯曲刚度的线性项与非线性项,以及弯曲刚度的变化范围。采用分段研究的方法,给出索股钢丝的弯曲剪切力公式。通过研究索股钢丝逐层滑移,推导钢丝在各个滑移位置的轴力和钢丝层间剪切力与索股曲率或转角的关系。结合钢丝层的滑移判定条件关系式,推导出与滑移位置对应的转角,并给出简化模型下的弯矩-转角图和弯曲刚度-转角图。结合索股拉弯模型试验,同时建立索股的ANSYS分层滑移模型,探讨了索股弯曲特性的影响因素。轴向应力增大或等效缠丝力减小,索股的初滑移转角减小,索股钢丝越早出现滑移且滑移速率越快,弯曲刚度越早减小。当钢丝未出现滑移时,截面弯矩和弯曲应力将随着轴向拉应力的增大而增大,但不受等效缠丝力影响。等效缠丝力越大,钢丝滑移的极限摩擦力越大,钢丝滑移越慢,截面上的不均匀应力越大,全滑移过程对应的转角变化范围越大,且全滑移后的弯矩更大。
[Abstract]:The main cable strands of the suspension bridge are composed of a large number of discrete parallel steel wires. The mechanical characteristics of the cable strands are quite different from those of the whole section formed by homogeneous materials, especially when the cable strands section is subjected to bending, the steel wire of the same section may slip. In this case, the section deformation will no longer satisfy the assumption of plane section, and the calculation of bending stress needs the help of complex nonlinear finite element method. In this paper, taking the parallel wire strands under the combined force of tension and bending as the research object, considering the actual situation of the layered cable strands and sliding in stages, a method for analyzing the mechanical characteristics of the parallel steel wire strands under the combined force of tension and bending is established. A simplified nonlinear bending method for parallel steel wire strands is established by comparing with the experimental results and the results of nonlinear finite element method. The main contents of this paper are as follows: the main reason for the bending stress of cable bending beams is that the slippage between steel wires is not considered. For cables with steel wire slippage, the sectional moment of inertia between two adjacent initial slip angles of steel wire is considered to be invariant, and the relationship between the curvature of cable bending and the angle of cross section rotation is deduced. A formula for calculating the bending shear force along the axial length of the cable is given. On the basis of the physical equation, the strain, stress and internal force of cable are decomposed into linear and nonlinear terms, the tangent stiffness matrix of the relation between internal force and deformation is derived, and the linear and nonlinear terms of bending stiffness are obtained. And the range of bending stiffness. The formula of bending shear force of cable-strands steel wire is given by using the method of subsection study. By studying the slippage of cable-strand steel wire layer by layer, the relationship between the axial force of steel wire at each slip position and the shear force between steel wire layers and the curvature or rotation angle of cable strand is deduced. Based on the relationship between slip and slip of steel wire layer, the rotation angle corresponding to the slip position is derived, and the moment-rotation diagram and the bending stiffness-angle diagram are given under the simplified model. In this paper, the ANSYS delamination slip model of cable strands is established in combination with cable tension and bending model test, and the factors influencing the bending characteristics of cable strands are discussed. With the increase of axial stress or the decrease of equivalent wire winding force, the initial slip angle of cable strand decreases. The earlier the wire slips and the faster the slip rate is, the earlier the bending stiffness decreases. When the steel wire does not slip, the cross section bending moment and bending stress will increase with the increase of the axial tensile stress, but will not be affected by the equivalent wire winding force. The larger the equivalent wire winding force is, the greater the ultimate friction force of steel wire slip is, the slower the steel wire slip is, the larger the inhomogeneous stress on the section is, the larger the range of rotation angle is corresponding to the whole slip process, and the greater the bending moment is after the whole slip process.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441;U448.25
本文编号：2343244
[Abstract]:The main cable strands of the suspension bridge are composed of a large number of discrete parallel steel wires. The mechanical characteristics of the cable strands are quite different from those of the whole section formed by homogeneous materials, especially when the cable strands section is subjected to bending, the steel wire of the same section may slip. In this case, the section deformation will no longer satisfy the assumption of plane section, and the calculation of bending stress needs the help of complex nonlinear finite element method. In this paper, taking the parallel wire strands under the combined force of tension and bending as the research object, considering the actual situation of the layered cable strands and sliding in stages, a method for analyzing the mechanical characteristics of the parallel steel wire strands under the combined force of tension and bending is established. A simplified nonlinear bending method for parallel steel wire strands is established by comparing with the experimental results and the results of nonlinear finite element method. The main contents of this paper are as follows: the main reason for the bending stress of cable bending beams is that the slippage between steel wires is not considered. For cables with steel wire slippage, the sectional moment of inertia between two adjacent initial slip angles of steel wire is considered to be invariant, and the relationship between the curvature of cable bending and the angle of cross section rotation is deduced. A formula for calculating the bending shear force along the axial length of the cable is given. On the basis of the physical equation, the strain, stress and internal force of cable are decomposed into linear and nonlinear terms, the tangent stiffness matrix of the relation between internal force and deformation is derived, and the linear and nonlinear terms of bending stiffness are obtained. And the range of bending stiffness. The formula of bending shear force of cable-strands steel wire is given by using the method of subsection study. By studying the slippage of cable-strand steel wire layer by layer, the relationship between the axial force of steel wire at each slip position and the shear force between steel wire layers and the curvature or rotation angle of cable strand is deduced. Based on the relationship between slip and slip of steel wire layer, the rotation angle corresponding to the slip position is derived, and the moment-rotation diagram and the bending stiffness-angle diagram are given under the simplified model. In this paper, the ANSYS delamination slip model of cable strands is established in combination with cable tension and bending model test, and the factors influencing the bending characteristics of cable strands are discussed. With the increase of axial stress or the decrease of equivalent wire winding force, the initial slip angle of cable strand decreases. The earlier the wire slips and the faster the slip rate is, the earlier the bending stiffness decreases. When the steel wire does not slip, the cross section bending moment and bending stress will increase with the increase of the axial tensile stress, but will not be affected by the equivalent wire winding force. The larger the equivalent wire winding force is, the greater the ultimate friction force of steel wire slip is, the slower the steel wire slip is, the larger the inhomogeneous stress on the section is, the larger the range of rotation angle is corresponding to the whole slip process, and the greater the bending moment is after the whole slip process.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441;U448.25
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