（1 江苏省苏科建设技术发展有限公司， 南京 210008； 

2 江苏省建筑科学研究院有限公司， 南京 210008）

［摘要］基于结构的动力特性，针对某超长大跨网架结构的初步设计方案的合理性进行了研究。初步方案中网架采用横向桁架体系，搁置在下部独立钢柱上，网架内部横向桁架之间仅存在纵向水平连系杆，整体结构低阶自振模态为水平横向的半波振动，不同于一般网架结构的竖向振动，且基本周期达到0.62s，说明其整体刚度较弱，且刚度不合理。为改善结构自振模态，加强结构整体性，采取多种优化措施，包括增设横向和纵向的水平剪刀撑、纵向斜腹杆以及下部支承结构的连系梁，增加支承结构抗侧刚度等。研究表明这些措施所起的作用是不同的，针对超长大跨网架结构，要综合考虑屋盖和下部支承刚度才能保证结构整体刚度的合理性。

［关键词］网架； 模态分析； 刚度； 优化

中图分类号： TU242.5 文献标识码： A文章编号：  1002-848X(2016)S2-0391-05

Modal analysis and stiffness optimization of over-long and large-span lattice grid 

structure

Dong Weidong 1,2

（1 Jiangsu Suke Construction Technology Co．， Ltd．， Nanjing 210008, China；

2 Jiangsu Research Institute of Building Science Co．， Ltd．， Nanjing 210008, China）

Abstract: Based on the dynamic characteristics of structure, the rationality of the preliminary design scheme of over-long and large-span lattice grid structure is researched. The lattice grid composed of transverse trusses lay on the under independent steel columns, there are only longitudinal horizontal tie bar between transverse trusses in lattice grid′s interior, the low-order mode is horizontal transverse half-wave which is different from vertical vibration of the general lattice grid, and the basic period is 0.62s, that is to say, structural global stiffness is weak. So that, several measures are adopted to improve mode and strengthen structural stiffness, including adding transverse and longitudinal horizontal bridging, longitudinal web member, tie girders between steel columns, lateral force resistance of under bearing. Results indicate the effect of these measures is different, considering stiffness of the roof and under bearing at the same time can insure the rationality of the structural global stiffness during designing over-long and large-span gird structure. 

Keywords: lattice grid； modal analysis； stiffness； optimization