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Title: Structural evaluation of a novel box beam system of Pultruded Fibre Reinforced Polymer shapes
Author: Evernden, Mark
ISNI:       0000 0001 3455 3218
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2006
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Presented in this thesis is an evaluation of a novel box beam system of Pul- truded Fibre Reinforced Polymer (PFRP) shapes. The flat-pack modular beam system consists of separate PFRP flange and web shapes joined together with a new method of mechanical fastening. It is based on the first generation Star- tlink building system, conceived by UK engineers in 1999. The Startlink building system is introduced, and classified within the scope of Modern Methods of Con- struction (MMC), and its merits are discussed. In the context of MMC a critical review by the author finds that, although the proposed 1999 generation Startlink system offers design flexibility, it will probably have a limited market potential. The novel use of the steel MlO Unistrut connection method as a means of fastening distinct PFRP shapes in a building system is characterised. Individ- ual connector design parameters for joint stiffness and resistance are identified and determined, under pure shear loading. The results of a series of physical tests show no significant loss of stiffness or strength with long term environmen- tal exposure. Values of key mechanical properties for design calculations are recommended. A 400 x 200 x 2848 mm prototype PFRP box beam assembly is fabricated from two flange and two web panel-type shapes, cut from existing off-the-shelf PFRP shapes. This is 60 mm deeper than the largest single PFRP shape that could be used as a beam. The assembly is joined at the web-flange junction with M10 Unistrut connectors set at various spacing's, in the range 50 to 400 mm. These connectors carry the longitudinal shear that is generated between the joined shapes when the modular assembly is in flexure, Theoretical deflections, cal- culated using a modified form of a partial-interaction analysis model developed for composite concrete and steel structures, are predicted for the assembly ac- counting for the finite shear stiffness of the web-flange connection. A series of 16 four-point bending load tests on the beam assembly, across two load arrange- ments, show that its performance is linked to the designated spacing of the M10 Unistrut connections. The flexural rigidity and degree of interaction present in the assembly are determined from analysis of vertical deflections and longitudi- nal strains, as the beam is deformed. The influence of secondary effects, due to the poor tolerances achieved in the hand fabrication of the beam's assembly, are found to greatly affect the ability of the deflection analysis to give the required measured deflections. Comparison of the effective joint shear rigidities obtained from theory and testing indicates a higher individual connection stiffness in the prototype beam than previously determined by way of the individual Unistrut connector characterisation. It is found through the combined analytical and physical testing research that the M10 Unistrut connection method can only provide the necessary joint shear stiffness and resistance to the 400 mm deep beam if the connector spacing, along the four joints, is ≤ 50 mm. The total number of connectors this represents in the beam is likely to make this modular construction approach too expensive for it to be commercially viable. Although the M10 connector could be used to fabricate beams of lesser depths, since the number of connectors will then be reduced, these beams would find it difficult to compete with the available off-the-shelf PFRP beam shapes, of up to 300 mm deep. There is however scope to use the Unistrut method of connection to provide longitudinal shear resistance in building systems where, for example, a floor panel is to be stiffened by a channel shaped beam and the overall depth is ≤ 300 mm. The research work contained in this thesis has contributed to a radical change in the PFRP product offerings now proposed in the 2006 generation Startlink building system.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TA Engineering (General). Civil engineering (General)