Optimum Design And Sliding Resistance Of Scaffold Wall Components With Variable Bearing Capacity

Connecting wall is a component used in the construction site to connect scaffolding frame with the main structure of the building,which can transmit tension and pressure.Under various horizontal loads such as wind load,the horizontal anti-sliding bearing capacity of connecting wall directly determines the overall stability of scaffolding.Scaffold collapse safety accidents caused by insufficient anti-sliding bearing capacity of connecting walls frequently occur,resulting in significant economic losses and casualties.Therefore,carrying out the calculation of the horizontal anti-sliding bearing capacity and optimizing the structure of the connecting wall will help to further improve the safety of scaffolding.Based on the principle of energy,the formulas for calculating the static friction and sliding friction of metal surface are obtained,and the sliding resistance of single fastener wall components is analyzed and calculated according to the variation of friction with time and sliding speed.The matrix displacement method is used to analyze the relationship between the friction forces of double fastener wall components when they are not sliding,and the sliding resistance of double fastener wall components is calculated.Based on the exponential attenuation friction model,the stress nephogram and friction time history curves of single and double fastener wall joints at different time were simulated by using finite element software ABAQUS,and the corresponding influence parameters were analyzed.Based on the work done,the following conclusions are drawn::(1)The maximum static friction force is 11.268 kN and the sliding friction force is 7.967 kN.When the double fastener wall is not sliding,the friction force between the fastener near the stress end and the steel pipe is larger,while the friction force far from the stress end is smaller,and the sliding resistance of the double fastener wall is obviously less than 2 times of the single fastener.(2)The larger the spacing between fastener A and B,the larger the friction ratio between fastener B and A,and the linear relationship between them.At the same time,the smaller the anti-sliding bearing capacity of double fastener wall is.The theoretical calculation value of the sliding bearing capacity of single and double fasteners is in good agreement with the test value of the code.The structural form of variable bearing capacity wall element is proposed.(3)Finite element simulation results show that the maximum and minimum anti-sliding bearing capacity of double fasteners are 66 KN,61KN and 35 KN respectively.The anti-sliding bearing capacity of double fasteners is between [1.74,1.83] times of that of single fastener,which is in good agreement with the theoretical value.(4)In single and double fasteners,the greater the bolt pretension force,the greater the friction force of fasteners A and B,and the greater the anti-sliding bearing capacity of double fasteners,but it is not linear;the friction dissipation energy caused by steel tube slip is two orders of magnitude times of the static friction state of the wall.(5)Connecting wall is in static friction state.Considering plastic deformation,the friction force of fastener A and B changes alternately during loading,which is more conducive to the whole function of connecting wall.Before reaching the maximum static friction force,the friction force of fastener A and B can produce greater shear bearing resultant force.(6)At the moment of steel tube slip,whether plastic deformation is considered or not,the sliding friction force tends to increase.Plastic deformation has a lag effect on the time of sliding and the increase of friction force is larger,resulting in less friction dissipation energy.