Static and fatigue performance of resin injected bolts for a slip and fatigue resistant connection in FRP bridge engineering

This paper presents test results to evaluate the slip and fatigue performance of Resin Injected Bolted
Joints (RIBJs) for pultruded Fibre Reinforced Polymer (FRP) material. The objective of the test
series is to provide a robust method of connection for structural engineering that is both fatigue and
slip resistant. Forty-six joints (using 23 specimens) were subjected to either static or combined
static/cyclic loading at ambient room temperature. Ten specimens (five batches of two) had bolted
connections without injected resin and were included to provide baseline static joint strengths.
Sikadur®-30 and RenGel®-SW404 were the two cold-curing epoxy based resins used to fabricate
the 13 RIBJ specimens. Testing was conducted with double lap-shear joints in accordance with
modified guidance from Annex G and Annex K in standard BS EN 1090-2:2008. The specimen’s
geometry was established using this British Standard and an American Society of Civil Engineers
pre-standard for pultruded thin-walled structures. Rectangular plates for the lap joints were cut from
either a wide flange section of size 254×254×9.53 mm or a flat sheet of 6.35 mm thickness. Bolting
was with either M16 or M20 steel threaded bolts of Grade 8.8. Sixteen specimens, for eight batches
of two specimens were failed in a short duration for static strength. Four RIBJ specimens had static
load cycling to an assumed service load level. Three specimens out of 23 were subjected to staged
static and cyclic fatigue loadings to determine stiffness changes, life-time ‘slip’ load and residual
joint strength. The reported results are evaluated for slip and fatigue performance and the main
finding is that resin injection shows much promise as a mechanical method of connection in
pultruded FRP structures.