Structural Performance Analysis And Safety Evaluation Of Cantilevered Fastener Scaffolding

Cantilevered scaffold is widely used in high-rise construction projects because of its advantages of safety,easy installation,and freedom from floor height and site restrictions.However,insufficient structural design,material defects,unsafe handling of staff,influence of external environment and failure of management personnel will directly affect the stability of the frame and the life safety of operators.At present,the evaluation of scaffolding scheme is mainly determined by experts combining their own experience through inspection and calculation,and there is no comprehensive and systematic safety evaluation method.Therefore,in this paper,the structural performance analysis and safety evaluation of the cantilever fastener type scaffold are carried out.The main results are as follows:A scaffolding model based on semi-rigid joints was established by Midas.By changing the three translational stiffnesses and three rotational stiffnesses of the fastener connection node,the stable bearing capacity of the scaffold was analyzed in turn when the relative restraint stiffness was 0.01%,10%,20%,50%,70%,90% and 100%.Based on the ratio of the test stiffness to the theoretical stiffness,the relative restraint stiffness was obtained.The finite element model with the same proportion as the test was established by Midas.The finite element model and the test results were compared and analyzed.The results showed that the stable bearing capacity and failure mode are basically similar,which proves that the relative restraint stiffness value proposed in this paper is reasonable.Using Midas modeling to analyze the stable bearing capacity and buckling mode of the scaffold under different synchronizing distance,longitudinal distance,transverse distance,diagonal brace,tie member,number of fastener failures and vertical pole failures,and the optimal layout parameters of scaffold are obtained,which provides a reference for practical engineering application.The results show that the scaffolds with different spacing,scissor bracing arrangements and wall-connection arrangements mainly suffer from overall buckling failure,and the bearing capacity and displacement decrease with the increase of spacing.Reducing the spacing in the step direction of the connecting wall parts can effectively improve the bearing capacity of the scaffolding.The bearing capacity of the scaffold decreases linearly with the increase of the number of fastener failures,and local instability failure mainly occurs.The further the failure position of the pole is,the smaller the stable bearing capacity of the scaffold is.When the pole fails,the scaffold mainly suffers from local instability and damage.Based on the simulation analysis results of scaffold under different structural parameters,a comprehensive and systematic safety evaluation index system for cantilever scaffolding was constructed.The evaluation model of grey relative Euclidean weighted correlation theory based on the combined weight of AHP and CRITIC method is established,and the feasibility of the evaluation model is tested through three engineering projects.It is proposed that the safety evaluation project should be above the level of Ⅲ,which provides a theoretical basis for practical engineering applications.