Study On Stability Bearing Capacity Of Disc-fastened Steel Tube Formwork Supporting Frame

Since the steel tube formwork bracket has been widely used,the collapse accidents of the formwork bracket have occurred all over the country.It is urgent to have a further understanding of the stable bearing capacity of the formwork bracket and reduce the occurrence of Engineering accidents.Through theoretical analysis,experimental research and finite element simulation,this paper studies the calculation method and influencing factors of the stability bearing capacity of disc-fastened steel tube formwork bracket.The main research contents and conclusions are as follows:1.Taking the unit frame of disc-fastened formwork support frame as the research object,nine kinds of unit frame test under different erection conditions were carried out.The test results show that the reduction range of bearing capacity is larger when the height of the unit frame without inclined bars increases than that with inclined bars;when the height remains unchanged,the increase of the spacing of the vertical bars reduces the height-width ratio of the frame,which can improve the stability bearing capacity of the vertical bars;the installation of inclined bars on the erection body will significantly improve the stability bearing capacity,and the increase range is related to the way and quantity of the inclined bars.2.The finite element software ANSYS is used to simulate the test conditions.The results of the finite element simulation are compared with the test results,which verifies the rationality of the finite element simulation.Then,the whole frame of disc-fastened formwork support frame is simulated and studied.The results show that the increase of the spacing,step distance,sweeping pole height,frame height,ratio of the top extension length of the pole to step distance will reduce the stable bearing capacity of the frame;the installation of vertical inclined poles in the frame will significantly improve the stability bearing capacity,while the installation of horizontal inclined poles will increase the stability bearing capacity of the frame.It is suggested that the setting of horizontal inclined rods should be taken as a structural measure to improve the safety reserve of the frame.3.On the basis of previous research results,some simplifications and assumptions are made for disc-fastened formwork support frame.The calculation methods of seven-bar model based on frame column with lateral displacement(hereinafter referred to as the seven-bar model with lateral displacement),single-bar model with lateral displacement and table-looking method based on finite element simulation results are introduced,and the expressions and tables for calculating the stable bearing capacity of frame body are given.In view of the influence of the height of the frame,the ratio of the top extension length of the pole to the step distance on the stability bearing capacity of the formwork support frame,according to the simulation results of the finite element method,the corresponding correction coefficients are proposed for the calculation results of the seven-bar model with lateral displacement.4.The theoretical value,finite element simulation value and standard value of the seven-bar lateral displacement model are compared and analyzed.It is considered that the table-looking method based on finite element simulation results is a more accurate and easy-to-operate method for calculating the stability bearing capacity of the plate support frame.