Study On The Influence Of Height Variation Of Upper And Lower Ends On The Bearing Performance Of Disk Lock Steel Tubular Scaffold

Disk lock steel tubular scaffold has the characteristics of simple structure,long service life,convenient installation and so on.Compared with traditional scaffolding,its construction and removal speed is faster,and the construction efficiency is higher.At present,scholars at home and abroad have carried out in-depth theoretical and experimental analysis on the bearing capacity and stability of disk lock steel tubular scaffold,but there is a relative lack of research on the mechanical properties caused by the change of the height of the scaffold.This thesis carries out an experimental study on the influence of the height of the bottom sweeping rod and the length of the top cantilever end on the frame of disk lock steel tubular scaffold,and seven different groups of single-span two-step disk lock steel tubular scaffold frame are designed with the height of the sweeping bar and the length of the cantilever end as variables,and numerical simulation and parametric analysis are carried out through the finite element software to study the mechanical properties such as ultimate bearing capacity,stability,instability mode.The main research contents and conclusions are as follows:(1)By changing the height of the sweeping bar and the length of the cantilever end,the static loading test is conducted on seven groups of frames with different sweeping bar heights and different cantilever end lengths,strain gauges are arranged on the second step vertical bars,cross bars,and diagonal bars of the frame,and these displacement gauges are arranged on the two diagonal uprights of the frame,then the test measured data of bearing capacity,strain and displacement are compiled and analyzed.(2)By analyzing the ultimate bearing capacity,load-displacement curve and other mechanical properties of seven groups of disk lock steel tubular scaffold tests,it is found that:Under the condition of keeping the length of the cantilever end unchanged,the bearing capacity of the frame decreases by only 1.8%when the height of the sweeping bar is raised from 250mm to 400mm,and the instability mode mainly shows the overall counterclockwise distortion;When the height of the sweep bar exceeds 400mm,the load capacity of the frame decreases the most by about 14%,and the instability also occurs mainly at the bottom of the vertical bars,and the bottom is bent sideways in the same direction instead of twisted;When the length of the cantilever end is raised from 360mm to 650mm with the same height of the floor sweeper,the load-bearing capacity of the frame decreases by about 24%,and there is an obvious and rapid decrease,and the instability of the frame also shows counterclockwise twisting;When the length of the cantilever end exceeds 650mm,the load-bearing capacity of the frame is still decreasing,but the decrease is slow,and the instability of the frame mainly occurs at the top position of the vertical bars,and the top of the vertical bars bend sideways in the same direction.(3)These models of seven groups of test frames are established by the finite element software Hypermesh,and the buckling analysis are carried out by the finite element software ABAQUS.The results of numerical simulation and the test results are compared and analyzed,and the errors between the simulated and test values are within 15%,which indicates that the finite element model established in this paper has good applicability.(4)Based on the finite element numerical simulation,the analysis of parameters such as the length of the steel pipe at both ends of the vertical bar,the diameter of the steel pipe of the vertical bar,the wall thickness of the vertical bar,the spacing of the vertical bar,the left height of the cross bar and the form of diagonal bar erection are carried out to explore the influence of these parameters on the mechanical performance of the disk lock steel tubular scaffold.Parameter analysis shows that:the best design length of steel pipe at the bottom of the upright is 300mm～350mm,and the best design length of steel pipe at the top of the upright is 260mm～310mm,which provides scientific suggestions and valuable references for the practical engineering application of disk lock steel tubular scaffold.