某钢网架加固设计

Strengthening Design of a Steel Grid Structure

某网架因施工遗留问题和使用荷载的增大,导致结构存在质量安全隐患。系统地介绍了网架加固方案:受压杆件采用薄壁槽钢、薄壁矩形管或角钢作为外加约束单元的增大截面法进行加固,受拉杆件采用新增双拼槽钢的增大截面法进行加固,螺栓采用在原螺栓球节点上焊接鼓筒节点或增设高强对拉螺杆的方法进行加固。采用MST和NIDA软件进行了结构模型验证并使用直接分析法对网架进行承载力计算,并对压杆加固方案进行了精细化有限元分析,对比分析了加固杆件和未加固杆件的荷载-位移曲线和破坏模式。结果表明:压杆加固后,构件承载力提高了15%~33%,破坏模式由失稳破坏向强度破坏转变;整体加固完成后,在荷载增加并考虑初始缺陷和整体缺陷的情况下,网架结构可以满足《建筑结构可靠性设计统一标准》(GB 50068—2018)的要求。

Due to the problems left over from construction and the increase of service load,a grid structure project has hidden trouble of quality and safety.This paper systematically introduces the reinforcement scheme of the grid structure,the compression rods are strengthened by using thin-walled channel steel,thin-walled rectangular pipe or angle iron as the external constraint element.The tension rods are reinforced by adopting the double channel steel to increase the cross section.The bolts are reinforced by welding drum joints on the original bolt ball joints or by adding high strength pull screws.MST and NIDA software are used to verify the structure model and direct analysis method is used to calculate the bearing capacity of the grid.Strengthening plans are introduced and refined finite element analysis is carried out on the reinforcement scheme of the compression rod.The load-displacement curves and failure modes of reinforced and unreinforced rods are compared.The results show that,after reinforcement,the bearing capacity of rod is increased by 15%~33%and the failure mode changes from unstable failure to strength failure.After the overall reinforcement is completed,under the condition of increasing loads and considering the initial and overall defects,the grid structure can meet the requirements of Unified Standard for Reliability Design of Building Structures(GB 50068—2018).