Experiments On Bend Fatigue Behavior Of Composite Deck System With Steel-ultra Thin UHPC-TPO Layer

As an important part of the steel bridge deck structure, the steel bridge deck pavement has been paid more and more attention by the academic and engineering circles. For a super-long span bridges which are very sensitive to the dead weight, a new method of steel-ultrathin UHPC-TPO composite bridge deck is proposed in this paper.This paper is based on the Humen bridge as the engineering background, to be on the steel-ultrathin UHPC-TPO pavement system of flexural fatigue performance of the study, this paper mainly completed the following work:Study on static bending test of steel-ultrathin UHPC-TPO composite plate. The experimental results show that the TPO is more nonlinear than the UHPC, and when the crack width of the UHPC layer is 0.2mm, the TPO is not cracked, and it still has a strong ability of deformation. When the composite plate is damaged, the slip between the steel-UHPC layers is small, and the maximum slip is 3.12mm; the TPO-UHPC interface has no obvious change. Using elastic analysis method to calculate the cracking strength of UHPC was 22.08~24.28 MPa, greater than the real bridge load under the action of UHPC top surface of the transverse tensile stress; when the width of cracks of UHPC 0.05 mm, TPO layer had no visible cracks, TPO cracking strength should be over at the corresponding calculation of pull stress 6.15 MPa, is much higher than that of the real bridge load cross bridge to the maximum tensile stress of TPO. The ultimate flexural capacity of steel-UHPC-TPO composite plate is calculated by the plastic analysis method, and the results are compared with the experimental results.Combined with the finite element analysis method, the bending fatigue behavior of the composite plate is studied. The results show that the steel bridge deck-ultrathin UHPC-TPO pavement system under the most unfavorable load conditions,the finite element calculation of transverse UHPC layer maximum pull should6.93 MPa, cross the bridge to TPO layer maximum pull should 1.04MPa; composite slabs in UHPC layer pull stress amplitude the fatigue load effect of the1.9MPa~9.3MPa(pulsating equivalent stress is 8.5MPa) and UHPC layer tensile stress amplitude 2.9MPa~14.0MPa(pulsating equivalent should force of 13.2MPa) of fatigue loading, has loaded 200 million times and 337 million times, UHPC surface layerwidth is 0.05 mm cracks and TPO surface always no cracks appear. Composite plate alone in the tensile stress amplitude of 2.9MPa~14.0MPa(equivalent fluctuating stress 13.2MPa) under the fatigue load, after a load of times, the maximum crack width of UHPC 0.05 mm, TPO still no visible cracks appear. TPO showed good resistance to crack growth; the composite plate decreased by 13.1% and 9.6%respectively before and after fatigue test, and the residual strength decreased by 15%and 11% respectively, which showed good tensile fatigue resistance.Damage-fracture mechanics and Miner linear theory were used to establish the fatigue damage model and predict the fatigue life of the steel bridge deck and ultrathin UHPC-TPO composite pavement system.