Cold - Formed Structures

Part1.

Introduction

1.1 TYPES AND SHAPESStructural members are mainly used in the higher range of thickness, as beams for comparatively low loads on small spans (purlinsand rails), as columns and vertical supports, and as bars in trusses.The depth of CF members ranges from 50 to 300 mm and the thickness of material ranges from 1.0 to 8.0 mm, although depth and thickness outside these ranges also are used

Cold-formed (CF) structural products can be classified into three main typologies:

omembers

osheeting

osandwich panelsCold-Formed Structures (Part 1.4)Prof. RaffaeleLandolfo-University of Naples "Federico II"

Sheeting are plane load bearing members in the lower range of thickness, generally used when a space covering function under moderate distributed loading is needed, e.g. roof decks, floor decks, wall panels. The depth of panels generally ranges from 40 to 200 mm and the thickness of material ranges from 0.5 to 2.0 mm.

Cold-formed (CF) structural products can be classified into two main typologies:

omembers

osheeting

osandwich panelsCold-Formed Structures (Part 1.4)Prof. RaffaeleLandolfo-University of Naples "Federico II"

1.1 TYPES AND SHAPES

Three generations of sheeting

The first generation includes plane trapezoidal profiles without stiffeners, allowing spans between secondary members of no more than 3 m.In the second generation the trapezoidal sheets are stiffened in longitudinal direction by appropriate folding and may span up to 6 -7 m.The third generation profiles are trapezoidal units with both longitudinal and transversal stiffeners, which provide suitable solution for spans up to 12 m without purlins.1st generation2nd generation3rd generationCold-Formed Structures (Part 1.4)Prof. RaffaeleLandolfo-University of Naples "Federico II"

1.1 TYPES AND SHAPES

The prefabricated sandwich panels are particularly suitable because they provide thermal insulation at the same time as the basic weather shield It consists of two metal faces bonded to an internal layer of rigid foamSuch panels may be installed very quickly thus saving time on site

Cold-formed (CF) structural products can be classified into two main typologies:

omembers

osheeting

osandwich panelsCold-Formed Structures (Part 1.4)Prof. RaffaeleLandolfo-University of Naples "Federico II"

1.1 TYPES AND SHAPES

CF sections can be generally obtained through two manufacturing methods:The process of cold-rolling is widely used for the production of individual structural members and corrugated sheeting. The final required shape is obtained from a strip which is formed gradually, by feeding it continuously through successive pairs of rolls which act as male and female dies. 1.2 COLD -FORMING TECHNIQUES 2.discontinuous process: press braking or folding Press braking FoldingIn these processes, short lengths of strip are fed into the brake and bent or pressed round shaped dies to form the final shape. Usually each bend is formed separately and the complexity of shape is limited to that into which the die can fit.1.continuous process: cold -rolling Cold-Formed Structures (Part 1.4)Prof. RaffaeleLandolfo-University of Naples "Federico II"

The feature 2.gives rise to local buckling phenomena, which penalisethe load-bearing capacity.As a consequence, structural analysis and design of thin-walled CF elements is generally complicated by the effects arising from the above features, which do not affect the structural response of more simple and compact sections.

Cold-Formed (CF) Structures

Prof. Raffaele Landolfo

University of Naples "Federico II"