Fatigue behavior of steel ring confinement for a clustered stud shear connector in full-depth precast concrete bridge deck panel

Abstract

Steel L-angle ring confinement for a cluster of large size studs was found to be the effective resistance for transferring composite actions between the full-depth precast concrete bridge deck panels and steel girders. However, the behavior of this type of confinement is still unclear under the repetitive service load condition. The research investigates fatigue behavior of L-angle steel ring with hook bars for confining a cluster of 4 large size studs (31.8 mm diameter) in the composite full-depth concrete deck system under cyclic loads. Three Push-off specimens were loaded repetitively from the hydraulic jack to observe the fatigue resistance of the deck, the studs, and the ring confinement. The load ranges and cycles of loading were based on fatigue resistance of an individual stud in according to AASHTO LRFD 2012 design specification. The cyclic service loads were performed in a range from 0 to 294 kN (30 Ton-force) in about 3,000 cycles. With initial load ranges from 0 to 98 kN (10 Ton-force) in 1,000 cycles, the fatigue shear resistance could reach higher about 100% as seen by twice number of loading cycles. The loading cycles had more influence than the load range limits in terms of service life, and vice versa in term of resistance. Visual inspections detected initial cracks at the top surface of the concrete deck nearby the jacking zone. With higher load ranges, cracks were propagated to the concrete deck bear to the shear pocket, and finally caused permanent bent out to the ring confinement. However, the splits of concrete were still in place because of hook bars welded to the ring confinement.