Keywords: steel structures, joints, finite element analysis, plastic analysis, non-linear analysis.

The structural analysis of an outdoor footbridge constructed from a 3D tubular steel truss structure is presented. Special emphasis was given to the study of the joints, of two different types: a "T" joint and a "KT" joint. Chords are made of 3008 RHS sections and the braces of 2608 RHS sections. The behaviour of the structure is discussed and analysed using the Eurocode 3 [1] methods and finite element models.

For RHS joints, the traditional methods to derive the failure load of the chord face are: (i) plastic analysis with straight or curved yield line patterns, e.g the studies of Cao et al [2], Packer [3], Packer et al [4], Kosteski et al [5], Davies and Packer [6] and Gomes [7], and (ii) deformation criteria limits based on a percentage of the chord face width or thickness. The studies of Korol and Mirza [8], Lu et al [9], and Zhao [10] are referred. The results from these criteria are presented and discussed, and the Eurocode 3 [12] design rules are briefly presented as well. The adopted joint geometries are slightly outside the validity range of this code.

The developed finite element models using thick shell elements for both joints are described. The results from material and geometric nonlinear analysis are presented and discussed.

It was found, for the "T" joint, that failure occurs by the chord face, with large out-of-plane deformations and membrane stiffness, where the parameter (brace width to chord width ratio) plays a fundamental role on the joint resistance and behaviour, as already extensively pointed out by the authors having studied the subject in the past, namely Neves [11].

The application of Eurocode 3 [12] yield line bending mechanisms to relative large values of this parameter may lead to quite unsafe results. On the other hand, deformation limit criteria have shown to be adequate for the particular geometry studied.

For the "KT" joint, the ruling failure mode is the brace failure, as predicted by the Eurocode 3 [12]. A reasonable agreement was found between this code provisions and the numerical results.

1

CEN, Eurocode 3, EN1993-1-1: Design Steel Structures, May 2003, CEN, European Committee for Standardization, Brussels, 2003.

2

Cao, J.J., Packer, J.A., Young, G.J., Yield line analysis of RHS connections with axial loads, J. Constructional Steel Research, 1998 vol. 48, no. 1, pp 1-25. doi:10.1016/S0143-974X(98)90143-2

3

Packer, J.A., Moment Connections between Rectangular Hollow Sections, J.Constructional Steel Research 25, 1993, pp 63-81. doi:10.1016/0143-974X(93)90052-T

4

Packer, J.A., Wardenier, J., Kurobane, Y., Dutta, D., Yeomans, N., Assemblages de sections creuses rectangulaires sous chargement statique predominant. Série CIDECT "Construire avec des profiles creux", Verlag TUV Rheinland, Köln, 1993.

5

Kosteski, N., Packer, J.A., Puthli, R.S., A finite element method based yield load determination procedure for hollow structural section connections, J. Constructional Steel Research, vol. 59, no. 4, pp. 427-559 (April 2003). doi:10.1016/S0143-974X(02)00066-4

6

Davies, G., Packer, J.A., Predicting the strenght of branch plate - RHS connections for punching shear, Canadian Journal of Civil Engineering, 9, no. 3, 1982, pp 458-467.

7

Gomes, F.C.T., Etat Limite Ultime de la Résistance de L'âme d'une Colonne dans un Assemblage Semi-Rigide d'axe Faible, Rapport Interne no. 203, MSM - Université de Liège, 1990.

8

Korol, R., Mirza, F., Finite Element Analysis of RHS T-Joints, Journal of the Structural Division, ASCE, vol.108, No. ST9, Sep. 1982, pp 2081-2098.

9

Lu, L.H., de Winkel, G.D., Yu, Y., Wardenier, J., Deformation limit for the ultimate strength of hollow section joints, 6th International Symposium on Tubular Structures, Melbourne, Australia, 1994, pp 341-347.

10

Zhao, X, Hancock, G., T-Joints in Rectangular Hollow Sections Subject to Combined Actions, Journal of the Structural Division, ASCE, vol.117, No. 8, Aug. 1991, pp2258-2277. doi:10.1061/(ASCE)0733-9445(1991)117:8(2258)

11

Neves, L.F.C., Monotonic and Cyclic Behaviour of Minor-axis and Hollow Section Joints in Steel and Composite Structures, Doctoral Thesis, University of Coimbra, 2004.

12

CEN, Eurocode 3, EN1993-1-8: Design of Joints, May 2003, CEN, European Committee for Standardization, Brussels, 2003.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £135 +P&P)