Design of Cold-Formed Steel Purlins Attached to Roof Sheeting Based on Eurocode 3: Effect of Gravity Load

Abstract

In the design of cold-formed steel purlins based on Eurocode 3, the lateral bending moment in the free flange of the purlin, when in tension, is assumed to be zero due to flange curling and second order effects. To investigate the validity of this design assumption, non-linear analytical and finite element models for analyzing how the gravity load affects the maximum mid-span stresses in cold-formed steel purlins attached to the roof sheeting are presented in this paper. The second-order effect of tensile stresses induced by the gravity load in the free flange of purlins is investigated by emphasizing on Z and C sections. The results obtained from the two models are compared with Eurocode 3, and they are included in this article. It is observed that for shorter purlin span lengths the design assumption underestimates the maximum mid-span stresses.

Keywords

purlin sheeting rotational restraint gravity load elastic foundation non-linear analyses

Get full access to this article

View all access options for this article.

References

Peköz

and Soroushian

(1982). “Behaviour of C and Z-purlins under wind uplift”, Proceedings of the Sixth International Specialty Conference on Cold-formed Steel Structures, St Louis, MO.

Sokol

(1996). “Stability of cold formed purlins braced by steel sheeting”, Thin-Walled Structures, Vol. 25, No. 4, pp. 247–268.

Tomà

and Wittemann

(1994). “Design of cold-formed purlins and rails restrained by sheeting”, Journal of Constructional Steel Research, Vol. 31, No. 2–3, pp. 149–168.

Jiang

and Davies

J.M.

(1997). “Design of thin-walled purlins for distortional buckling”, Thin-Walled Structures, Vol. 29, No. 4, pp.189–202.

Rousch

C.J.

and Hancock

G.J.

(1997). “Comparison of tests of bridged and unbridged purlins with a non-linear analysis model”, Journal of Constructional Steel Research, Vol. 41, No. 2, pp. 197–220.

Zhi-Ming

Kettle

and Li

(2004). “Analysis of cold-formed zed-purlins partially restrained by steel sheeting”, Computers & Structures, Vol. 82, No. 9, pp. 731–739.

Lucas

R.M.

Al-Bermani

G.A.

and Kitiporchai

(1997). “Modelling of cold-formed purlin-sheeting systems – part 1: Full model”, Thin-Walled Structures, Vol. 27, No. 3, pp. 223–243.

Lucas

R.M.

Al-Bermani

G.A.

and Kitipornchai

(1997). “Modelling of cold-formed purlin-sheeting systems – part 2: Simplified model”, Thin-Walled Structures, Vol. 27, No. 4, pp. 263–286.

European Committee for Standardization. (2003). Eurocode 3: Design of Steel Structures Part 1–3, “General rules for cold-formed thin gauge members and sheeting”, British Standards Institution, London, England.

10.

Vrany

(2002). “Torsional restraint of cold-formed beams provided by corrugated sheeting for arbitrary input variables”, Proceedings of the Eurosteel – The Third European Conference on Steel Structures, Coimbra.

11.

Katnam

K.B.

Van Impe

Lagae

and De Beule

(2007) “Rotational restraint in z-profile purlin-sheeting systems: FE mode”, Computational Methods, Liu

(eds), Springer, pp. 621–626.

12.

Thomasson

P.O.

(1988). On the Behaviour of Cold-formed Steel Purlins – Particularly with Respect to Cross Sectional Distortion, Baehre-Festschrift, Karlsruhe, Germany, pp. 281–292.

13.

ABAQUS (2004). ABAQUS standard user's manual – Version 6.5, Hibbitt, Karlsson and Sorenson, Inc., USA.