Theoretical And Experimental Study On The New Rigid Connection Of Steel Tube Structure

In practical engineering, a large number of steel tubes are connected with themselvesbecause of production, material cutting, transportation and other processing. The existingconnection way, such as welding connection, flanged and bolted splice construction, isdifficult to guarantee the quality and visual appearance. In order to improve the connectionmode, an inner set bolted connection is presented in this paper. This connection iscombination of the high-strength bolt and cruciform board. The joint is hidden inside thesteel tube. The connection will be used in highly required building appearance,construction environment and construction quality. Now the mechanical performance anddesign method of the connection has no related research. By using the finite element andexperiment, the connection on the mechanical properties under the action of axial force hasbeen studied in detail, and based on that, the paper gives the method of the design of theconnection.This experiment designs9full-scale specimens, including3compressed ones and6tensioned ones. Through analyzing the unidirectional loading experiment, the forcedproperties of specimens under the action of axial force are well understood. It turns out thatthis connection can transfer the force effectively. Steel tube connected to the cruciformboard length has a great influence on the specimen of bearing capacity and failure pattern.By using the finite element software ANSYS to establish finite element model of thenew rigid connection, the geometric nonlinearity and material nonlinearity factors areconsidered. It turns out that the model of this paper can simulate connection under theaction of axial force of the stress state when comparing the results of the finite elementwith the experiment. By building the finite element model in this paper, the connectionparameters are analyzed. It turns out that it has3parameters relations of failure modes andthe ultimate capacity including: the ratio of flute length and outer diameter of the steel tube:α=Lw/D, the ratio of the sectional area of cruciform inserted plate and net sectional area ofthe steel tube: γ=Ac/A, the ratio of the section area of the base plate and net sectional areaof the steel tube: δ=Ad/A. A large number of finite element analysis concluded the criticalvalue of each parameter: the failure occurred in the connected joints when calculated value is less than the critical value and the failure occurred in the steel tube when calculatedvalue is greater than the critical value.By using the equal strength design method to derive the simplified theoretical solution,combining the finite element, experiment and the simplified theoretical solution, thepractical calculation formula about the connection is given on this paper. The formula isproved to be corrected by comparing the bearing capacity of the same model in the ways offormula, experiment and nonlinear finite element. Eventually, the paper provides areference for the application in practical engineering by offering the design flow andadvices for the new rigid connection, as well as the table of selecting the materialscomposing connection.