一种板桁结合型加劲梁竖向抗弯刚度的近似算法

An Approximate Calculation Method for the Vertical Bending Stiffness of a Deck-Truss Composite Stiffener

板桁结合型加劲梁(后称加劲梁)因其刚度大、自重小等特点成为桥梁特别是大跨度桥梁的主要结构形式之一。为了解决加劲梁竖向抗弯刚度计算复杂的问题,基于前人已有的数据与研究,提出一种近似算法:首先统计了国内外26座典型加劲梁主要结构形式,并通过手算与电算分析不同结构形式的主桁架和下平联对竖向抗弯刚度的影响;其次,基于应变能互等原理将主桁架斜腹杆和下平联连续化处理为薄板结构;最后,通过加劲梁连续化等效的箱梁提出计算加劲梁竖向抗弯刚度的近似计算公式。研究结果表明:上述近似公式计算结果与加劲梁实际结构竖向抗弯刚度具有良好的吻合性,误差小于5%,可满足工程需要。

Being great in stiffness,but little in self-weight,and having other characteristics,the deck-truss composite stiffening girder(hereinafter referred to as the stiffening girder)becomes one of the main structural forms for bridges,especially for long-span bridges.In order to solve the problem in the complex calculation of the vertical bending stiffness of the stiffening girder,and upon the basis of the existing data and research fruits of our forefathers,put forward in the present paper is an approximate calculation method.Firstly,the main structural forms of the 26 typical stiffening girders both at home and abroad are counted,and the influences of different forms of the primary trusses and bottom lateral bracing on the vertical bending stiffness are analyzed either by hand calculation or by computer calculation.Secondly,according to the reciprocal principle of strain energy,the diagonal web members and bottom lateral bracing are continuously regarded as a thin-plate structure.Finally,according to a continuous equivalent box girder,an approximate method for calculating the vertical bending stiffness of the stiffening girder is proposed in the paper.The calculated result according to the above-mentioned approximate formula is found to be in good agreement with the actual vertical bending stiffness,with the error being less than 5%,which can meet the requirements of the project.