The Influence Of Defects Of The Tie Member Layout On Bending Moment Of The Scaffold Upright Tube

Scaffold is a temporary bracket for safety protection,worker operation and settlement of vertical and horizontal transport in constructions,Among them,the steel tubular scaffold with couplers has the advantages of convenient installation and disassembly,flexible erection,good versatility,comparative economy and so on,and has become one of the most widely used and common scaffold in China.However,with the development of China's construction industry,scaffold collapse accidents occur from time to time,resulting in a large number of casualties and economic losses,so it is necessary to study the safety control measures for the construction of the steel tubular scaffold with couplers.After analyzing the causes of the collapse of these steel tubular scaffold with couplers,it is found that the irregular setting of tie member is the main reason for the collapse of the scaffold.It is found that the specification of stipulates that the maximum distance of the tie member from the main node should not be greater than 300mm when the tie member is connected with the upright tube,and it does not specify how to set up the tie member at different heights of the scaffold.With the large number of high-rise and super-high-rise,the increase of construction height,the change of horizontal wind load is significant,and the defects such as different setting mode,deviation and connection of tie member have a significant effect on the scaffold rod parts.In order to clarify the influence degree of various unfavorable conditions on scaffold frame,it is very important to further study the influence of the setting defect of tie member on scaffold frame body.In this paper,we take the two steps and two spans of scaffold tie member as an example to study the effect of different connection modes and different distance between tie member and main node on the maximum bending moment of upright tube under wind load.This paper first considers the calculation method of the standard value of horizontal wind load under the influence of wind vibration,and then studies the influence of various defects when the tie member is set to the disadvantage on the construction scaffold upright tube under the wind load,and in this paper simulates the bending moment value of scaffold upright tube under six cases of continuous tie member setting by using the finite element software ANSYS software.In the simulation process,a semi-rigid node model is used to study the change law of the maximum bending moment of the upright tube when the tie member is setting different.In this paper,three kinds of working conditions are tested,respectively,the tie member is setting in the main node,the tie member deviate from the main node and the tie member deviate from the main node only connected with the inside upright tube,through the experimental study,the influence results of various construction defects of tie member are analyzed.Finally,the experimental results are compared with the semi-rigid joint finite element analysis of the test model,and the rotational stiffness of the coupler used in the finite element simulation is the measured value of the author in the structural laboratory,and the results of the finite element analysis are in good agreement with the test results.It is found that it is not suitable to use more than 100m super high-rise buildings for tie member to deviate from the maximum 300mm of the main node in the specification.When there is a defect that the tie member is not connected with the outside upright tube,the bending moment value of the inside upright tube is significantly increased,reaching no defects more than twice times.In this paper,a combination of simulation analysis and experimental research is used to give the concrete results of the influence of the tie member setting defects on the scaffold,and clarify the necessity that the tie member must be connected with the inside upright tube and outside upright tube at the same time,and discusses the reasonable distance of the tie member from the main node at different heights.It is hoped that the research in this paper can provide reference for the construction scaffold erection.