【摘要】：為分析剪切變形和剪力滯效應(yīng)對(duì)混凝土簡(jiǎn)支箱梁撓度的影響情況，參照我國(guó)高速鐵路32m箱梁尺寸，選取等截面簡(jiǎn)支梁為研究對(duì)象，采取解析與有限元數(shù)值相結(jié)合的方法進(jìn)行計(jì)算。以經(jīng)典Euler-Bernoulli梁理論、Timoshenko梁理論以及基于能量變分原理的剪力滯理論為基礎(chǔ)，從理論上對(duì)剪切變形及剪力滯效應(yīng)對(duì)箱梁撓度的影響機(jī)理進(jìn)行了深入探討。按照彎曲變形、考慮剪切變形、同時(shí)考慮剪切變形和剪力滯效應(yīng)三種情況，計(jì)算了自重、均布荷載及集中荷載作用下箱梁的撓度解析值。采用ANSYS中的beam4、beam189、solsh190單元建立模型，得到了荷載作用下箱梁撓度的數(shù)值解。以有限元數(shù)值解為基礎(chǔ)，對(duì)比分析了剪切變形和剪力滯效應(yīng)對(duì)箱梁撓度影響的大小。通過(guò)保持截面幾何參數(shù)不變，，改變箱梁跨徑大小，分析了隨著高跨比的變化剪切變形對(duì)撓度的影響規(guī)律，得到了箱梁考慮剪切變形影響的高跨比門檻值。依據(jù)Timoshenko梁理論對(duì)剪切修正系數(shù)的定義，通過(guò)有限元數(shù)值解進(jìn)行逆推，得到了同一截面類型箱梁的剪切修正系數(shù)。結(jié)論如下： （1）針對(duì)本文算例，自重作用下箱梁彎曲變形撓度解析解與數(shù)值解相同，為8.1666mm�？紤]剪切變形影響后撓度解析解為9.0187mm，數(shù)值解為9.0936mm，誤差為0.82%，原因是解析解中計(jì)算剪切修正系數(shù)時(shí)腹板面積近似取值引起的。同時(shí)考慮剪切變形及剪力滯效應(yīng)影響后撓度數(shù)值解為9.8492mm。 （2）相對(duì)于彎曲變形撓度，自重作用下考慮剪切變形及剪力滯效應(yīng)影響后撓度增大20.60%，其中考慮剪切變形影響的撓度增大率為11.35%，考慮剪力滯效應(yīng)影響的撓度增大率為9.25%，剪力滯效應(yīng)對(duì)撓度的影響略小于剪切變形的影響。 （3）按照本文計(jì)算結(jié)果，當(dāng)高跨比小于1/16時(shí)，剪切變形附加撓度占彎曲變形撓度的百分比才開始小于5%，即在工程上可忽略不計(jì)。當(dāng)高跨比等于1/5時(shí)，考慮剪切變形產(chǎn)生的附加撓度占彎曲變形撓度的50%以上。因此，實(shí)心截面是否考慮剪切變形影響的高跨比門檻值1/5對(duì)于箱梁而言是不合適的，本文采用箱梁截面其高跨比門檻值為1/16。 （4）對(duì)于本文所研究箱梁截面，其剪切修正系數(shù)可參考取值0.2326。即腹板計(jì)算高度可取頂板與腹板交匯中心到底板上表面的距離，其結(jié)果是偏于安全的。 （5）對(duì)箱梁進(jìn)行力學(xué)分析時(shí)假定其約束是施加在中性軸上的，但實(shí)際工程中通過(guò)支座對(duì)梁體進(jìn)行約束，當(dāng)約束施加在支座位置時(shí)，其腹板中性軸處跨中撓度增大值為0.4288mm，相當(dāng)于彎曲變形撓度的5.25%。所以實(shí)際撓度應(yīng)該在考慮剪切變形、剪力滯效應(yīng)影響的基礎(chǔ)上再加上因?qū)嶋H約束位置的不同而產(chǎn)生的附加撓度。
[Abstract]:In order to analyze the influence of shear deformation and shear lag effect on the deflection of simply supported concrete box girder, referring to the size of 32 m box girder of high-speed railway in China, a simple supported beam with equal section is selected as the research object. The analytical method combined with finite element method is used to calculate. Based on the classical Euler-Bernoulli beam theory and the shear lag theory based on the energy variational principle, the influence mechanism of shear deformation and shear lag effect on box girder deflection is discussed theoretically. According to the bending deformation, the shear deformation and the shear lag effect, the deflection of the box girder under the action of gravity, uniform load and concentrated load is calculated. The model is established by using the element Beam4 Beam189 and solsh190 in ANSYS, and the numerical solution of box girder deflection under load is obtained. Based on the finite element numerical solution, the effects of shear deformation and shear lag on the deflection of box girder are compared and analyzed. By keeping the geometric parameters of the section unchanged and changing the span size of the box girder, the influence of shear deformation on the deflection with the change of the ratio of height to span is analyzed, and the threshold value of the high span ratio of the box girder considering the effect of shear deformation is obtained. According to the definition of shear correction coefficient based on Timoshenko beam theory, the shear correction coefficient of box girder of the same section type is obtained by the inverse deduction of finite element numerical solution. The conclusions are as follows: (1) for the example of this paper, the analytical solution of bending deflection of box girder subjected to self-gravity is the same as the numerical solution, which is 8.1666 mm. After considering the effect of shear deformation, the analytical solution of deflection is 9.0187mm, the numerical solution is 9.0936mm, and the error is 0.82mm, which is caused by the approximate value of web area when calculating the shear correction coefficient in the analytical solution. Considering the effects of shear deformation and shear lag effect, the numerical solution of deflection is 9.8492mm. (2) relative to bending deflection, The deflection increases 20.60% after considering the effect of shear deformation and shear lag under gravity, in which the increase rate of deflection considering the effect of shear deformation is 11.35, the increase rate of deflection considering the effect of shear lag is 9.25, and the effect of shear lag is shadow of deflection. The response is slightly smaller than the effect of shear deformation. (3) according to the results of this paper, When the ratio of height to span is less than 1 / 16, the percentage of additional deflection of shear deformation to bending deflection begins to be less than 5, that is, it is negligible in engineering. When the ratio of height to span is equal to 1 / 5, the additional deflection due to shear deformation accounts for more than 50% of the deflection of bending deformation. Therefore, it is not appropriate for box girder that the threshold value of high span ratio of solid section considering shear deformation is 1 / 5. In this paper, the threshold value of high span ratio of box girder section is 1 / 16. (4) for the box girder section studied in this paper, the ratio of height to span is 1 / 16. (4) for the box girder section studied in this paper, The shear correction coefficient can be referred to as 0.2326. That is, the web can calculate the distance between the top plate and the center of the web, and the result is safety. (5) the constraint of the box girder is assumed to be imposed on the neutral axis when the box girder is subjected to mechanical analysis. But in the actual engineering, the beam body is restrained by the support. When the constraint is applied to the support position, the increasing value of the midspan deflection at the neutral axis of the web plate is 0.4288mm, which is equivalent to 5.2525mm of the bending deformation deflection. Therefore, the actual deflection should be taken into account the shear deformation, shear lag effect and the additional deflection caused by the difference of the actual constraint position.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U441;U448.213

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 鄭健;;中國(guó)高速鐵路橋梁建設(shè)關(guān)鍵技術(shù)[J];中國(guó)工程科學(xué);2008年07期

2 劉世忠,吳亞平,夏e

本文編號(hào)：2191872