Mechanical Analysis Of Longitudinal Horizontal Tube Of Cantilever Scaffold

As an indispensable temporary support structure system for construction industry,scaffolding is particularly important in the era of high-rise and super high-rise buildings.The components of the scaffold are the vertical tubes,the transversal horizontal tubes and the longitudinal horizontal tubes,which are connected by fasteners.As high-rise and super-tall buildings reduce the land occupation rate of large-scale buildings,it brings great space and convenience to the crowded urban areas.High-rise and super-tall buildings are built in large numbers,however,with the increase of building height and wind load,the stress of scaffold becomes more and more complex,which brings unprecedented challenges to the construction.Most of the previous scaffolding researches focused on the arrangement of scaffolding and tie member,the performance of fasteners and vertical tubes.In China,there are few studies on the performance of longitudinal horizontal tubes under various working conditions of fastener-type cantilevered steel tubular scaffolding.The reasonable force and safety of the longitudinal horizontal tubes are related to the safety of the construction of the entire frame.In this paper,in the face of different working conditions that may be encountered during construction,the longitudinal performance of the longitudinal horizontal tubes is studied in depth.Aiming at the high-rise building construction scaffolding,considering the wind-induced vibration factors of horizontal wind load,the force behavior and internal force variation of the longitudinal horizontal tube under the combined action of wind load and vertical construction load are studied.The ANSYS finite element software is used to simulate the closeness of the frame.In the case of force,the nodes are simulated with semi-rigidity.Using the simulation method of this paper,the feasibility of the simulation method in this paper is verified by the analysis of the previous test frame.Taking into account the current requirements of the "Safety Technical Specifications for Fastener-type Steel Tubular Scaffolding for Building Construction",the requirements for limiting the deviation of the tie member from the main node of 300 mm are given.For higher building construction,the tie member is offset from the main node by 300 mm,Whether the requirement is applicable or not is an unknown conclusion.As the construction height and difficulty increase,this specification requires that the analysis conclusions that specifically meet the construction safety requirements should be given for different working conditions and load conditions.In this paper,according to the change of wind load when the scaffold is at different height from the ground,considering the construction load on the scaffold board and various working conditions,this paper analyzes the internal force change of the longitudinal horizontal bar,and analyzes the internal force change of the longitudinal horizontal tube whenthe tie member deviate from different degrees along the vertical and horizontal directions and are connected with the inner and outer rows of vertical tubes.At last,the internal force variation rule of the longitudinal horizontal tube of the scaffold under ten different working conditions and the safety applicable conditions of the longitudinal horizontal tube of the scaffold under different working conditions are given.For the sake of safety,the working condition of tie member only with inner tube is studied.According to the result of simulation analysis,the dangerous reason of tie member only with inner tube is given,and the feasibility of this working condition is denied.The analysis also shows that the stress of the longitudinal horizontal bar will move along the deviation direction of the connecting wall when the connecting wall is deviated.With the increase of the construction height,the limit of the deviation degree will be smaller and smaller.The article gives the requirements of the deviation limit and analyzes the reasons.It is hoped that the research in this paper can provide reference for the safe construction and modification of relevant specifications.