Pultruded sections

Glass reinforced pultruded plastic sections such as Extren(25) have been used where corrosion resistance, thermal and electrical nonconductance or non-magnetic properties were required. It is possible to fabricate large assemblies using bolting techniques (e.g. Fig. 

but development work is necessary to explore the opportunities for bonding. 

There exist a number of instances in which cladding panels, comprising various materials, are bonded directly into curtain 

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Pultruded sections are used for handrails, cable trays, ladders and even bridge construction. The parallel orientation of the continuous fibres ensures that they are protected with a covering of resin, which enhances weathering properties a polyester veil can be used to improve protection. Despite this, some deterioration in surface gloss is experienced fairly rapidly on standard pultrusions if a surface coating is not used, but mechanical properties are retained for many years. 

Apart from the wet processes it is also possible to make pultruded sections from prepregs. The forming procedure is the same as that used with wet resin systems. The prepreg is drawn through a heated die which melts the resin, compresses the prepreg into the required shape and cures the resin. This is a somewhat cleaner process than that using a resin bath. 

P(6) Pultruded sections consist of a sequence, usually sjmunetrical and... 

P(l) The effects of type, volume fraction and orientation of the reinforcement in each lamina (ply) or layer, and the thickness, stacking sequence and number of laminae or layers on the structural behaviour of the laminate or pultruded section shall be assessed. 

It may not always be possible to achieve this, however, particularly with pultruded sections. 

For pultruded sections recommended joining techniques (see Figure 5.31)... 

The members to be joined are typically pultruded sections having closed... 

Bonded inserts are typically used with pultruded sections or with similar types of components having closed cross-sections. 

P(5) When the manufacturer makes a standard range of FRP products, for example pultruded sections, tests such as load-deflection tests and dimensional checks shall be carried out on fabricated elements. 

Where the product is a standard item, for example a standard pultruded section, the test samples in (10) should be used to check conformity with the properties specified by the manufacturer. Typical specified properties might include ... 

Where the structure is made of individual components such as pultruded sections, tests should be carried out on t3rpical elements in accordance with 7.3.2, unless sufBcient relevant data are available from the component manufacturer. 

Bonded inserts are typically used with pultruded sections or with similar types of components having closed cross-sections. The inserts may be bonded either on the outer or inner surface of the section. The sections are typically loaded in axial tension or compression or in bending, resulting in shear loadings (primarily) in the bonded joint. 

The degree to which it is appropriate to take samples from the structure and the value of the material properties so obtained will depend on the nature of the particular programme of work. For a simple structure, such as a frame made up of standard pultruded sections, the basic material properties will be of little benefit apart from providing a check that the sections are within specification. (However, even this would probably be better done by testing full components.) For a more complex structure, say a shell of variable thickness, a knowledge of the localised properties could be essential. 

Alternatively, if the structure is formed of standard components, such as pultruded sections, tests may be carried out on similar components or data obtained from standard information sheets supplied by the manufacturer, provided that it is agreed that they are representative of those in the complete structure. 

Five tests on frame sub-assemblies have been conducted to study the behaviour of web cleated connections made of pultruded section. Full-size beam-to-column connections were tested to failure. Four of them were made by bolting but in one specimen bonding alone was used. The test method gave indicative results on the moment-rotation response of each connection in a frame. Results are used to provide simple design guidance for nominally pinned connections. 

Once the pultruded section has left the die and cooled sufficiently, it is clamped and a flying saw moves along with the clamped section to cut off required lengths. Extra long lengths can be accommodated by feeding the pultrusion out through a door, window or hatch... 

For optimum properties, all pultruded sections will require post curing and care must be taken to ensure adequate support along the entire pultruded length to prevent deformation occurring in the post cure oven. 

Pultruded sections are attractive alternatives to steel sections where either strength or mass is important. If extra stiffness is required of the GRP sections, this could be achieved by increasing the overall dimensions. 

Davies P, Choqueuse D, Bigourdan B, Gauthier C, Joannic R, Pameix P, LTlostis I (2004) Design, manufacture and testing of stiffened panels for marine structures using adhesively bonded pultruded sections. J Eng h rine Environ 218(M4) 227-234... 

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