The Study On Scaffold Tie Members Design Method In High-rise Building Construction

Scaffold is a temporary and indispensable structure to building construction.Design and using of scaffold are related to the construction safety and quality.With the rapid development of construction industry,a growing number of high-rise and super-high-rise building structures are emerging.Nowadays,cantilevered steel tubular scaffolds with couplers are popularly used in high-rise building construction.Scaffold tie members maintaining scaffold safety and stability are the key components of the scaffold.Construction industry standard "Technical code for safety of steel tubular scaffold with couplers in construction"(JGJ130-2011)states:when building height exceeding 100m or scaffold height of more than 20m above the cantilevered channel steel,after specializing analysis on wind pressure characteristic value of wind loads,scaffold,couplers,the tie member,details and ect,while having made the appropriate measures to strengthen and implement program,construction could be permitted.The standard "Technical code for safety of steel tubular scaffold with couplers in construction"(JGJ130-2011)there is no clear theory and design methods in this regard.There are a lot of blind phenomenon in current construction,because most accidents of scaffold was due to unreasonable tie member design.Therefore,this paper devoted to theoretical research in this area.The scaffold loads are more complex because of a large amount of increasingly building height.Horizontal wind loads effect also significantly.Nowadays,in our construction industry,It's lack of relevant practical system design studies on scaffold and tie member under wind loads for high-rise buildings.Because previous studies mostly concentrated on the performance of couplers joint and formwork elastic-plastic analysis.We realize that safety is the most important issue for a temporary scaffold structure.Elastic ultimate limit states design method reliably avoid too deforming of steel tubular and result in easy turnover use of steel tubular.Starting research from the analysis of scaffold wind loads,according "Load code for the design of building structures"(GB50009-2012),studying on the role of different parameters of wind load,proposal is pointed that wind vibration factor can not be ignored and vibration factor calculation methods formula was given.Then based on "Technical code for safety of steel tubular scaffold with couplers in construction"(JGJ130-2011),wind shape factor calculation analysis and recommendations formula is also given.The theoretical wind characteristic value formula,which includes factors such as vibration factor,shelter factor of shape factor,height exposure factor,was gotten.In order to investigate the relationship between the tie member with the force transmission system to the distribution of scaffold rods,the article studied the control one of internal forces under the ultimate state loads.The result shows that the scaffold reasonable lift height,longitudinal spacing,tie member position and even the tie member elastic ultimate limit state design formulas are feasible.According to the analysis,including analysis of two groups of six specimens and test point dates measured and analysis of comparison with the theoretical calculation and two groups,we found that the elastic calculation model of hinged joints with each other of frame body is close to the measured and the actual value when the fastener torque 50N · m.The proposed hinged joints calculation model is safety and feasible for scaffold system design.This essay presents basis theoretical and design methods for tie member and scaffold system,such as,tie member layout methods,tie member feasible position,scaffold suitable maximum height above ground,details and elastic ultimate limit state design formula.we would like to provide some references for scaffold design and for the revision of code.