基于几何正装法的N式钢桁梁桥预拱度设置研究

Study on Pre-camber Setting for N-type Steel Truss Bridge Based on Geometric-forward-installation Method

针对N式钢桁梁桥,通过对钢桁梁节点坐标的求解模拟钢桁梁的无应力安装过程,提出了一套预拱度设置计算方法。首先采用几何正序拼装方法,以节段桁式矩阵、节间长度矩阵和理论预拱度为输入参数,依次计算杆件伸缩值的精确解。然后根据制造精度调整杆件伸缩值,以实际杆件制造长度计算厂制预拱度。最后根据节点坐标计算各杆件平面角度,为设置错孔角提供依据。利用数学软件编制了相应程序,并与实际工程灌河特大桥项目的设计数据进行了对比,证明该方法可行。

The process of unstressed-state installation of N-type steel truss bridge was simulated by solving the truss nodal coordinates,a pre-eamber setting method was proposed in the paper.Firstly taking girder type matrix section length matrix and theoretical pre-eamber as the input parameters,the exact value of each chord expansion was calculated one segment by another in a geometric-forward-installation process.Secondly,the pre-eamber was calculated based on the actual length of the chords,then the value of expansion was adjusted according to manufacturing precision.Finally,the plane angles of the chords were calculated based on the node coordinates so as to provide a reference for setting the hole angle.A program was developed for the method by using the mathematical software.The calculated results were compared with the design data of Guanhe bridge project /which proved the feasibility of the method.