Fatigue behaviour of bonded anchors subjected to tensile loads

Following recent studies on the fatigue behaviour of noise barriers for high speed railways for train transits, threaded rods bonded with epoxy resin for column base plate anchorage had to be qualified. A fatigue test campaign was carried out at Fischer Laboratories in Denzlingen (Germany) on M20 and M30 (8.8 Grade) threaded rod samples embedded in concrete by means of FIS EM epoxy resin. The tests considered also threaded rods (M16 and M30, 8.8 Grade) not directly embedded in concrete, but in pre-cast corrugated pipes having a diameter constant and equal to 40 mm. The results were found to be very satisfactory as far as the resin performance was concerned. In fact, under tensile loads carried out under a nominal load ratio R 0, all fatigue failures took place in the threaded rods, under the nut, notwithstanding the embedment length was that suggested by technical manuals for static loading. Some typical fracture surfaces relating to medium and high cycle fatigue regime are documented. A statistical re-analysis has been carried out considering also other data, either obtained at Fischer laboratories from analogous threaded applications or taken from the literature. A new scatterband is provided for threaded rods with diameter equal to or less than 20 mm.