Abstract: The invention discloses a method and a system for predicting the corrosion fatigue life of prestressed concrete bridges. A corrosion level of the strand is predicted to obtain the residual tension force of a structure. A stress concentration factor is integrated to consider the stress concentration effect caused by pitting corrosion, and a growth model of the elastic stress of the strand under the coupled effect of corrosion and fatigue is proposed. A growth model of the plastic stress of the strand is established using a cross-section loss of the strand as a fatigue damage parameter based on a degenerated elastic modulus of the concrete after fatigue. Failure criteria for the concrete, the strand, and a longitudinal tension bar are defined, so that a set of methods for analyzing the life of a prestressed concrete bridge subjected to corrosive environment and fatigue load are formed.

Abstract: A Bailey beam for reinforcement is composed of Bailey panels, stiffening rods, bolts, anchor bolts, a prestressing tendon and anchorages. The components of the Bailey beam are all prefabricated in a factory, and are assembled and hoisted on site. The prestressing tendon is arranged in a lower chord of the Bailey beam, and is anchored to the stiffening rods at both ends. The Bailey beam slides towards both ends during prestress tensioning. In this case, the Bailey beam is lifted as a whole, and the prestressing force is applied to a lower edge of the Bailey beam, resulting in an inverted arch of structure, closing up of cracks and a decrease in downward deflection. After the completion of the prestress tensioning, sealing is performed by fixing fillers, a sealing steel plate and injecting solidifiable materials.

Abstract: The present invention provides a method for predicting prestress loss after concrete cracking along strand. Corrosion-induced cracking is modeled by the thick-wall cylinder theory, the expansive pressure is evaluated with the residual tensile stress by cracked concrete and confining stress by un-cracked concrete during concrete cracking process. Considering the effect of strand corrosion, the bond strength of corroded strand is evaluated from the contributions of adhesion stress, confinement stress and expansive pressure. A method for prestress loss in corroded pre-tensioned concrete member is proposed with the strain compatibility and force equilibrium equations, incorporating the coupling effects of concrete cracking and bond degradation. The present invention proposes a method for predicting the prestress loss after concrete cracking along strand, which can incorporate the coupling effects of concrete cracking and bond degradation.

Abstract: An arch foot maintaining device includes a plurality of supporting structures, and the supporting structure includes a base, two base supporting seats, a hydraulic jack, a roller, and a roller supporting seat. The base is a cuboid with equal length and width, a through hole running through side surfaces of the base is provided on the base. A vertical guide groove is provided on each of the two base supporting seats. The roller supporting seat is U-shaped and located between the two base supporting seats, and the roller is rotatably supported in the roller supporting seat. Two ends of a central axis of the roller are respectively located in the two guide grooves, the hydraulic jack is disposed within the base, and a top of the hydraulic jack abuts against a bottom of the roller supporting seat.

Abstract: The invention discloses a method and a system for predicting the corrosion fatigue life of prestressed concrete bridges. A corrosion level of the strand is predicted to obtain the residual tension force of a structure. A stress concentration factor is integrated to consider the stress concentration effect caused by pitting corrosion, and a growth model of the elastic stress of the strand under the coupled effect of corrosion and fatigue is proposed. A growth model of the plastic stress of the strand is established using a cross-section loss of the strand as a fatigue damage parameter based on a degenerated elastic modulus of the concrete after fatigue. Failure criteria for the concrete, the strand, and a longitudinal tension bar are defined, so that a set of methods for analyzing the life of a prestressed concrete bridge subjected to corrosive environment and fatigue load are formed.

Abstract: The invention discloses an arch foot maintaining device and a maintenance method for achieving multi-degree-of-freedom displacement of an arch foot. The device includes a plurality of supporting structures, and the supporting structure includes a base (1), two base supporting seats (7), a hydraulic jack (2), a roller (3), and a roller supporting seat (4). The base (1) is a cuboid with equal length and width, a through hole running through side surfaces of the base (1) is provided on the base (1). A vertical guide groove is provided on each of the two base supporting seats (7). The roller supporting seat (4) is U-shaped and located between the two base supporting seats (7), and the roller (3) is rotatably supported in the roller supporting seat (4). Two ends of a central axis (14) of the roller (3) are respectively located in the two guide grooves, the hydraulic jack (2) is disposed within the base (1), and a top of the hydraulic jack (2) abuts against a bottom of the roller supporting seat (4).

Abstract: A Bailey beam for reinforcement is composed of Bailey panels, stiffening rods, bolts, anchor bolts, a prestressing tendon and anchorages. The components of the Bailey beam are all prefabricated in a factory, and are assembled and hoisted on site. The prestressing tendon is arranged in a lower chord of the Bailey beam, and is anchored to the stiffening rods at both ends. The Bailey beam slides towards both ends during prestress tensioning. In this case, the Bailey beam is lifted as a whole, and the prestressing force is applied to a lower edge of the Bailey beam, resulting in an inverted arch of structure, closing up of cracks and a decrease in downward deflection. After the completion of the prestress tensioning, sealing is performed by fixing fillers, a sealing steel plate and injecting solidifiable materials.