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在桥宽与跨径之比小于0.5的桥跨结构中,一般认为桥梁横向挠曲线呈直线关系,则偏心受压法(或称刚性横梁法)得到广泛的应用。如果再考虑到主梁的弯扭藉合,则可推导出不同的偏心受压修正公式。理论与试验均证阴,横隔梁抗弯刚度远非绝对刚性,既使B/l≤0.5横向挠度也呈曲线(这里基本假定按两次抛物线变化规律)。而且在一般钢筋混凝土或预应力混凝土粱式桥中多采用T型或不对称I字型截面,梁自身抗扭能力不大相对于弯曲而言可以忽略不计,故可以不去考虑由于扭矩的修正。本文假定横向挠曲线,无论荷载作用位置如何均假定按二次抛物线变化规律,利用能量法及虚位移原理推导出偏心受压的修正公式(这里修正非直线的横向挠曲线的影响)。这将不仅适用于B/l≤0.5而且对于B/l≤1也可以采用,这样就扩大了修正式的适用范围,而代替计算较繁复的GM法及刚性梁法,而达到简单而实用的目的。
In bridge structures with a ratio of bridge width to span of less than 0.5, it is generally considered that the transverse flexural curves of bridges are in a linear relationship, and the eccentric compression method (or rigid beam method) is widely used. If we consider the bending and torsion of the main girder, we can derive different correction formulas of eccentric pressure. Both theoretical and experimental evidence Yin, Beijiao beam bending stiffness is far from absolute rigidity, even if B / l ≤ 0.5 transverse deflection is also a curve (basically assumed parabolic law changes twice). And in general reinforced concrete or prestressed concrete beam beam bridge more use of T-shaped or asymmetric I-shaped cross-section, beam torsional ability is not large relative to the bending is negligible, it can not consider the torque correction . In this paper, we assume that the transverse deflection curve assumes a quadratic parabola variation regardless of the loading position. The correction formula for eccentric compression is deduced using the energy method and the virtual displacement principle (here, the effect of the non-linear transverse deflection curve is corrected). This will not only apply to B / l≤0.5 but also to B / l≤1, thus expanding the scope of the application of the amendment, instead of calculating the more complex GM method and rigid beam method, to achieve a simple and practical purpose.