Abstract

Substantial experimental investigations[1,2]have been carried out to study the flexural behavior of steel storage rack beam-to-upright connections.However,the experimental procedures are expensive and time-consuming.Recently,the fracture theory has been developed for ductile metals[3,4],and is gradually being used to predict the strength and post-ultimate behavior of hot-rolled steel beam-toupright connections[5].However,very limited research can be found on the fracture simulation of cold-formed steel members and structures.Therefore,high accuracy numerical analysis,incorporating the geometrical nonlinearity,material nonlinearity and fracture,is required to predict the full-range moment-rotation behavior of beam-to-upright connections in steel storage racks.

This paper presents a finite element(FE)analysis of a typical steel storage rack beam-to-upright boltless connection.A three-dimensional numerical model is established via the finite element(FE)package ABAQUS considering the realistic interactions among different structural components,as illustrated in Figure 1.A calibrated fracture model is employed to research the possible fracture of the tab and the tearing of the upright wall.

Figure 1　FE model for a typical boltless connection

The test results of the connections presented in reference[6]are used to verify the established models.Comparisons of connection behaviors between the finite element models and the test results are performed in terms of the failure mode and the moment-rotation curve,as shown in Figure 2.The comparison results demonstrated that the established numerical model can successfully simulate the typical failure mechanisms and satisfactorily predict the full-range moment rotation behavior of connections.

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Figure 2　Comparation between FEA results and the test data for a typical boltless connection“1.8C4-B120-4T”

Finally,based on the developed model,the influences of the gap between end-connector and upright flange are examined.Six values of the gap,i.e.0.0 mm,0.5 mm,1.0 mm,1.5 mm,2.5 mm and 5.0 mm,were selected to investigate the effects of the gap on the connection behavior.The connection type“1.8C4-B105-4T”is used as an example.Based on the established FE model,six finite element models with the varied gap values were established and analysed.The numerical moment-rotation relationships of these connections are illustrated in Figure 3.It can be seen from the figures that the gap values,to varying extent,influence the connection behavior.

Figure 3　Moment-rotation relationships of connections with varied values of the gap

This study presents a refined numerical investigation of storage rack beam-toupright boltless connections.The FE model is validated against the test results in terms of the possible failure mechanisms and the full-range moment-rotation curves.The results show that the FE model can successfully simulate the failure mechanisms of boltless connections,i.e.tab crack and the tearing of the upright wall,and can satisfactorily predict connections'full-range moment-rotation behavior including the post-ultimate range.Finally,the proposed FE model is employed to evaluate the effects of the gap between end connector and upright face.The developed FE model can provide a numerical method to be used in the evaluation and design of mechanical connections in steel storage racks.