Computation And Analysis Of Reliability On Fasteners Steel Tubular Formwork

As a traditional formwork support system,modular formwork is easy to erect,and it is suitable for various sizes of beam and plate members,besides the cost of it is not high,so it has been widely used in construction.However,the collapse of the template often occurs during construction,causing casualties.So there are still many problems in the design and erection of the fasteners steel tubular formwork.Many scholars have done research on the fasteners steel tubular formwork.Based on previous research,according to reliability theory,the reliability of fasteners steel tubular formwork can be simulated by ANSYS12.0.The reliability under different working conditions can be solved,and draw some conclusions that are conducive to the actual construction.The main work of this article is as follows:(1)Analyzing the research status of fasteners steel tubular formwork internally and externally,combining "Safety Specifications for Construction Formwork"(JGJ 162-2008)and "Safety Specification for Construction-type Fastener-style Steel Pipe Scaffolding"(JGJ 130-2011),To discuss the drawbacks of the existing normative design methods,and put forward the idea of designing according to the reliability theory.(2)According to relevant regulations and other scholars' research results,the ultimate bearing capacity of the formwork support system is determined as a failure criteria.In conjunction with actual projects,template supports are erected in accordance with the specifications.Through statistics of other Scholars,and analyzing thickness and diameter data of the steel pipe.The statistics show that the average thickness of the steel pipe is about 2.93 mm,the standard deviation is 0.259,and the variation coefficient is 0.088,which is less than the specified 3.6mm,and is less than the allowable deviation 3.0mm.The mean diameter of the steel tube is 48.08 mm,the standard deviation is 0.590,and the coefficient of variation is 0.012.The tightening torque of the fastener is 35.91N·m,the standard deviation is 14.535,and the coefficient of variation is 0.405.The above statistical parameters serve as the basis for the probabilistic design.(3)Using the probabilistic design module of ANSYS,carrying out for 1000 times on the formwork under four working conditions by the way of Monte Carlo.They were the normal template formwork and the high-formwork support system,and the actual site erected formwork and the high-formwork support system.Through the sampling calculation,the probability cumulative distribution curve of the maximum axial force and the probability sensitivity of the maximum axial force are obtained,and the probability that the maximum axial force less than the ultimate bearing capacity can be obtained too.(4)According to the finite element calculation,the reliability is obtained,and the reliability indexes of the formwork support system under different working conditions are solved,and discovered by comparison,the reliable index of the fastener type formwork support system built according to the specification is smaller.Based on the sensitivity of the Monte Carlo simulation,the factors affecting the reliability of the fastener-style template support are studied.The main factors include tightening torque of fasteners,erection of sweeping rods,dead load and live load,as well as the horizontal and vertical distances.Finally,the relationship between the reliability index and the partial coefficient is introduced.Taking the ordinary formwork frame as an example,combined with the probability and statistical parameters of the dead load and live load,partial coefficient of resistance and load can be calculated.