Study On The Design And Construction Technology Of Beyond-height-limitation Steel Tubular Scaffold With Couplers

"Safety Technical Specification for Fastener-type Steel Pipe Scaffolding for Construction"(JGJ130-2011)stipulates that the height of the full house scaffolding shall not exceed 36m.However,the actual project often requires a scaffolding system with a height of more than 36m.At present,the research on the ultra-high fastener-type steel scaffolding system is not perfect.Therefore,it is necessary to study the super-high scaffolding system.In combination with the Zhengzhou Science and Technology Museum project,through the field test,the internal process of the main and auxiliary poles,horizontal poles,horizontal and vertical scissors supports during the construction operation of the ultra-high fastener scaffolding is monitored.Then,based on the field test The parameters are numerically simulated under the corresponding working conditions using finite element software,and the numerical simulation model and parameters are verified by the test results.Finally,the test results,the finite element analysis results and the comparison results based on the normative method are used to summarize the various components.The internal force distribution and its development law determine the optimal range of the auxiliary pole height,and study the factors affecting the internal force,deformation and stability of the frame.The main research results are as follows:(1)Studying the internal force distribution and development law of the pole through field experiments.The results show that the maximum internal force of the pole appears in the vertical transportation stage of the decoration material,and the internal force value is in the range of 10~15kN.From the same pole,the axial force distribution characteristics of the main pole are:middle>upper>bottom,auxiliary The axial force of the rod gradually increases from top to bottom in the height direction.Considering the lateral and vertical deformation of the rod,according to the finite element analysis results and the experimental results,the optimum range of the auxiliary pole height is 35%~50%of the total height of the super-high frame.(2)During the construction operation,the super-high scaffolding horizontal rods are under pressure.The axial force of the horizontal rod reaches or exceeds 9kN,and the specification stipulates that the design value of the anti-sliding bearing capacity of the right angle fastener is 8kN,which hides the safety risk.It is recommended to take measures to strengthen the horizontal pole lap when the actual erection is carried out to ensure reliable force transmission.(3)Through finite element analysis,it is found that the main failure mode of super-high scaffolding is the horizontal lateral displacement of the scaffold,and the overall lateral instability is collapsed;the first high-heavy scaffold yielding is about 1/5 of the upper part of the frame.The range is the weak part of the frame.It is recommended that the upper part of the frame body be restrained from lateral movement by means of the main structure"holding the column"and adding the wall member.(4)Apply a large load to different areas of the top surface of the super-high scaffold,and analyze the influence of the load position on the stability of the frame.The results show that the closer to the load stacking area on the top of the frame,the greater the local deformation of the pole,and even the overall deformation of the frame,which may lead to the overall instability of the scaffold.It is recommended to set a special loading area for the super-high scaffolding.When considering the convenience of material lifting and arranging the loading area on the top surface of the frame body,it should be arranged at the corner of the frame body,and partially strengthen the vertical rod below the frame body,and should not be arranged near the midpoint of the periphery of the frame body.(5)The large load of the super-high scaffolding tends to cause the instability of the part of the frame.The upper load of the actual frame is complex,and the height of the secondary pole should be increased below the concentrated loading area.If the load is greater than 5kN/m~2,the auxiliary pole should be straight through the top surface of the frame.(6)Using finite element software to analyze the bearing capacity of horizontal and vertical scissors.As the density of the scissor support increases,the ultimate bearing capacity is gradually increased.In order to prevent the instability of the frame,it is recommended that the vertical spacing of the horizontal scissors should be less than 6m(4 steps),and the horizontal spacing of the horizontal scissors will gradually decrease from the lower part to the upper part of the frame,in the direction of the short total frame size.The width of the vertical scissors should be reduced;the width of the vertical scissors should be 3~5m,and the angle with the horizontal plane should be less than 55°.