【摘要】：懸索橋主纜索股由大量離散的平行鋼絲組成,其受力特性與均質(zhì)一體材料形成的整體截面有較大的差異,尤其當(dāng)索股截面受到彎曲作用時,同一截面的鋼絲可能產(chǎn)生滑移,此時截面變形將不再滿足平截面假定、彎曲應(yīng)力的計(jì)算需借助復(fù)雜的非線性有限元計(jì)算方法。本文以拉彎力共同作用下的平行鋼絲索股為研究對象,考慮索股分層、分階段滑移的實(shí)際情況,建立了拉彎力共同作用下的平行鋼絲索股的力學(xué)特性分析方法,并通過與試驗(yàn)和非線性有限元計(jì)算結(jié)果對比,建立了簡化的平行鋼絲索股非線性彎曲計(jì)算方法。論文主要研究內(nèi)容如下:拉索彎曲的梁理論計(jì)算的彎曲應(yīng)力會偏大的主要原因是沒有考慮鋼絲之間的滑移。對于有鋼絲滑移的拉索,采用分段研究的思想,認(rèn)為在相鄰的兩層鋼絲初滑移轉(zhuǎn)角之間截面慣性矩保持為不變,推導(dǎo)拉索彎曲曲率的變化與截面轉(zhuǎn)角的關(guān)系,給出沿拉索軸向單位長度的彎曲剪切力計(jì)算公式。在物理方程關(guān)系的基礎(chǔ)上,將索股的應(yīng)變、應(yīng)力與內(nèi)力分解為線性項(xiàng)和非線性項(xiàng),推導(dǎo)內(nèi)力與變形關(guān)系的切線剛度矩陣,得出彎曲剛度的線性項(xiàng)與非線性項(xiàng),以及彎曲剛度的變化范圍。采用分段研究的方法,給出索股鋼絲的彎曲剪切力公式。通過研究索股鋼絲逐層滑移,推導(dǎo)鋼絲在各個滑移位置的軸力和鋼絲層間剪切力與索股曲率或轉(zhuǎn)角的關(guān)系。結(jié)合鋼絲層的滑移判定條件關(guān)系式,推導(dǎo)出與滑移位置對應(yīng)的轉(zhuǎn)角,并給出簡化模型下的彎矩-轉(zhuǎn)角圖和彎曲剛度-轉(zhuǎn)角圖。結(jié)合索股拉彎模型試驗(yàn),同時建立索股的ANSYS分層滑移模型,探討了索股彎曲特性的影響因素。軸向應(yīng)力增大或等效纏絲力減小,索股的初滑移轉(zhuǎn)角減小,索股鋼絲越早出現(xiàn)滑移且滑移速率越快,彎曲剛度越早減小。當(dāng)鋼絲未出現(xiàn)滑移時,截面彎矩和彎曲應(yīng)力將隨著軸向拉應(yīng)力的增大而增大,但不受等效纏絲力影響。等效纏絲力越大,鋼絲滑移的極限摩擦力越大,鋼絲滑移越慢,截面上的不均勻應(yīng)力越大,全滑移過程對應(yīng)的轉(zhuǎn)角變化范圍越大,且全滑移后的彎矩更大。
[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.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U441;U448.25

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