基于附加挠度的宽翼缘开口薄壁梁剪力滞效应分析

发布时间：2018-08-11 12:34

【摘要】：开口薄壁工字梁、T梁、双T梁在桥梁工程中应用十分广泛,随着预应力技术以及新材料的研发应用,薄壁梁翼缘板越来越宽,跨度也越来越大,梁中的剪力滞效应也越来越引起学术界与工程界的重视。剪力滞效应导致梁翼板与腹板相交处弯曲应力明显增大,且大幅度增大了薄壁梁的挠度,同时影响梁的极限承载力。所以如果工程设计时忽略剪力滞效应的影响,将会使结构存在局部破坏或结构失稳的安全隐患。本文围绕薄壁工字梁、T梁、双T梁的剪力滞效应开展相关的研究分析。主要内容包括:(1)以挠度和附加挠度作为广义位移,构造了工字梁、T梁、双T梁新的纵向位移函数,用能量变分法推导出了工字梁、T梁、双T梁剪力滞效应的若干解析解,同时给出了基于该方法的一维离散有限元计算格式。研究结果表明采用本文方法的可行性和可靠性,解决了传统剪力滞理论存在的剪力滞函数物理意义不明确、难以解决左端固支右端简支开口薄壁梁的响应量的问题。(2)采用以挠度为基础定义剪力滞系数,分析了影响工字梁、T梁、双T梁剪力滞效应的因素。研究结果表明宽跨比、宽高比对梁剪力滞效应影响较大,为工程上减小开口薄壁梁的剪力滞效应提出了合理的建议。(3)提出了新的基于附加挠度的正负剪力滞效应判别方法,对宽翼缘开口薄壁梁的正、负剪力滞进行了识别。分析了三种截面薄壁梁在不同约束下的正负剪力滞效应,同时研究了宽跨比、宽高比及翼板腹板厚度等对薄壁梁正、负剪力滞效应区间的影响。(4)采用弹性模量缩减法分析剪力滞效应对工字梁极限承载力的影响,并分析了影响其极限承载力的因素,研究表明宽跨比、宽高比与翼缘板厚度对其影响较大,而腹板厚度对工字梁极限承载力的影响并不明显。
[Abstract]:Open thin-walled I-beam and double-T beam are widely used in bridge engineering. With the development and application of prestressed technology and new materials, the flange plate of thin-walled beam is becoming wider and wider, and the span is becoming larger and larger. The shear lag effect in beam has attracted more and more attention from academic and engineering circles. The shear lag effect increases the bending stress at the intersection of the flange and the web, increases the deflection of the thin-walled beam, and affects the ultimate bearing capacity of the beam. Therefore, if the influence of shear lag effect is ignored in engineering design, there will be local failure or structural instability. In this paper, the shear lag effect of thin wall I-beam and double T-beam is studied and analyzed. The main contents are as follows: (1) taking deflection and additional deflection as generalized displacements, a new longitudinal displacement function of I-beam T beam and double T beam is constructed, and some analytical solutions of I-beam T beam and double T beam shear lag effect are derived by energy variation method. At the same time, the one-dimensional discrete finite element method based on this method is presented. The results show that the method is feasible and reliable, and the physical meaning of the traditional shear lag function is not clear. It is difficult to solve the problem of the response of the left and right simply supported thin-walled beams. (2) the shear lag coefficient is defined on the basis of deflection, and the factors that affect the shear lag effect of I-beam and double-T beam are analyzed. The results show that the ratio of width to span and the ratio of width to height have great influence on the shear lag effect of beams. The reasonable suggestions for reducing the shear lag effect of thin-walled beams with openings are put forward. (3) A new method for distinguishing positive and negative shear lag effects based on additional deflection is proposed. The positive and negative shear lag of thin-walled beams with wide flange openings are identified. In this paper, the positive and negative shear lag effects of three thin-walled beams with different cross-section are analyzed, and the effects of the ratio of width to span, the ratio of width to height and the thickness of webs on thin-walled beams are studied. (4) the influence of shear lag effect on the ultimate bearing capacity of I-beam is analyzed by means of elastic modulus reduction method, and the factors affecting the ultimate bearing capacity of I-beam are analyzed. The ratio of width to height and the thickness of flange plate have great influence on it, but the influence of web thickness on the ultimate bearing capacity of I-beam is not obvious.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O342

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