低真空高速磁悬浮简支管道梁结构优化设计研究

Structural optimization design study on ultra-high speed simply supported maglev-evacuated tube structure

低真空超高速磁悬浮管道运输系统是继高速铁路后能解决中长距离运输的有效途径。针对目前低真空预应力混凝土和钢−混凝土组合管道梁结构的优化设计研究较为欠缺的现状,以常用30 m跨低真空磁悬浮简支管道梁为对象,建立5种不同管道梁截面的ANSYS三维实体有限元模型,开展精细化的有限元数值仿真分析研究。考虑材料非线性特性,分析管道梁截面形式和预应力钢筋布置形式对预应力混凝土管道梁关键截面强度、刚度和自振频率的影响。同时,进一步研究组合管道梁上部钢壳厚度、横向加劲肋宽度和高度等参数对强度和刚度的影响。最后,综合5种管道梁截面的各项分析结果,得到了一种最优的截面形式。研究结果表明:下部U梁、上部圆形截面,以及直线布束的预应力钢筋更能满足管道梁的受力要求;钢−混凝土组合梁中上部钢壳厚度、横肋间距等均能显著影响刚度和强度,得到了最佳壁厚为50 mm,最佳横肋间距和高度为4 m和250 mm;跨中截面变形和受拉区混凝土应力是控制截面设计的关键参数,受压区混凝土应力及普通钢筋应力处于安全状态,各类截面预应力钢筋应力沿纵向分布较为均匀,截面1的预应力混凝土管道梁为最优截面。本文研究成果可为相关学者开展管道梁结构设计提供参考。

The maglev-evacuated tube system is an effective method to solve medium and long distance transportation after high speed railway.However,there is the lack of research on the optimization design of the prestressed concrete and steel-concrete Maglev-Evacuated Tube Structure(METS)at present.Therefore,the commonly used 30 m span sample supported METS was taken as an example to carry out the refined finite element numerical simulation analysis.Five 3-D solid ANSYS finite element models with different sections were established considering the nonlinear properties of materials.The influence of the section types and the layout of prestressed reinforcement on the structural strength,stiffness and natural frequency of the prestressed concrete METS were studied.The influence of the thickness of steel shell on the upper side,the width and height of transverse stiffener on many characteristic of the steel-concrete METS were studied.Finally,the analysis results of five tube sections were synthesized.An optimal METS section form was obtained.The results are drawn.The prestressed tendons with U shape at the lower side,circular section at the upper side and linear shape prestressed reinforcement can better meet the stress state of the METS.The thickness of upper steel shell and the spacing of transverse ribs in steel-concrete composite beams can significantly affect the stiffness and strength.The optimal thickness of steel shell is 50 mm.The optimal width and height of transverse stiffener is 4 m and 250 mm,respectively.The deformation and concrete stress in tension region of main span is the key parameters controlling design.The concrete stress and ordinary reinforcement stress in the compression area are in safe state.The stress of prestressed reinforcement of various sections is evenly distributed along the longitudinal direction.The Section one(prestressed concrete METS)should be selected as the optimal section.The present results can provide a reference for subsequent scholars to carry out the design of METS.