This paper reviews Fibre Reinforced Polymer (FRP) composites in Civil Engineering applications. Three FRP types are used in Structural Engineering: FRP profiles for new construction, FRP rebars and FRP strengthening systems. Basic materials (fibres and resins), manufacturing processes and material properties are discussed. The focus of the paper is on all-FRP new-build structures and their joints. All-FRP structures use pultruded FRP profiles. Their connections and joints use bolting, bonding or a combination of both. For plate-to-pate connections, effects of geometry, fibre direction, type and rate of loading, bolt torque and bolt hole clearance, and washers on failure modes and strength are reviewed. FRP beam-columns joints are also reviewed. The joints are divided into five categories: web cleated, web and flange cleated, high strength, plate bolted and box profile joints. The effect of both static and cyclic loading on joints is studied. The joints’ failure modes are also discussed.
Response of pultruded Fibre Reinforced Polymer (FRP) beam-to-column joints with steel bolted web cleats is studied through physical testing. Two joint configurations are considered with either three or two bolts per cleat leg, as per drawings in a pultruder's Design Manual. Moment-rotation curves, failure modes and potential performance gains from semi-rigid action are determined from two batches, each having six nominally identical joints. Results show that initial joint properties for stiffness and moment can possess, at 19 to 62%, an extremely high coefficient of variation. All joints failed by fracturing within the FRP column's flange outstands. Because this failure mode has not been reported previously there is a need to establish how its existence influences joint design. As joint properties for the three-and two-bolted configurations are not significantly different, the middle (third) bolt is found to be redundant. Damage is shown to initiate within the column flange outstands when the mid-span deflection of a 5.08 m span beam, subjected to a uniformly distributed load, is span/500. This is half the serviceability vertical deflection limit recommended in the EUROCOMP Design Code and Handbook. The mean joint moment resistance for design is established to be 2.9 kNm and this is 1.5 times the moment for damage onset.
h i g h l i g h t sMoment-rotation behaviour of pinned joints in pultruded frames is characterised. Joint stiffness is more variable than moment resistance. Both initial stiffness and moment classify the joints as nominally pinned. A single specimen measurement of stiffness is unsuitable for use in frame analysis. FRP web cleats can crack before the mid-span deflection of a beam exceeds span/340.
a b s t r a c tThis paper presents the test results to characterise the moment-rotation response of nominally pinned joints in frames of pultruded shapes. Mimicking conventional steel construction the major-axis beamto-column joints are formed using pultruded FRP web cleats having steel bolting. There are two joint configurations with either a single row of three or two bolts per cleat leg. Testing is conducted on nominally identical specimens to statistically quantify the key joint properties. The average stiffness of all joints at damage onset is found to be 50% more variable than the average moment resistance. The presence of 70% difference between the minimum and maximum initial stiffness measured makes a single specimen measurement for stiffness unsuitable for frame analysis. The initial stiffness of the two joint configurations classifies them to be nominally pinned. No appreciable difference in characteristics for the three and two bolt configurations is found; the middle-bolt is unnecessary as two bolts give same results. The most important finding is that delamination cracks, at the top of the FRP cleats, could initiate before the midspan vertical deflection of a simply supported beam with uniformly distributed load exceeds span/340.
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