External prestress strengthening method for prestressed concrete box-beam bridge

Abstract

The invention provides a reinforcing method for the prestressing force in vitro, and the reinforcing method aims at a prestressed concrete box girder bridge, and adopts a space steel truss installed inside a box girder as the anchorage and steering configuration of a prestressing force beam in vitro; the prestressing force beam in vitro is distributed under the condition of considering the damnification of the structure based on optimizing the calculating result, and adopts a beam distribution mode of combining a full-length beam and a fulcrum crest slab short beam, wherein, the crest slab short beam can be bended to the lower boom of the steel truss to be anchored to provide a ventral shield with pre-shearing force according to the split situation; the steel truss is distributed according to the requirements of anchorage and steering of the prestressing force beam in vitro, and a girder grillage is respectively arranged in the box girder firmly close to the ventral shield side; each merithal is provided with a horizontal bracing to provide the anchorage and steering configuration of the prestressing force beam in vitro, and at the same time, the rigidity and the shearing resistance bearing capacity of the ventral shield of the concrete box girder are enhanced; the steel truss and the box girder are connected into a whole by adopting a plant ribbon mode, thereby ensuring the dosage and the distribution of the prestressing force beam in vitro to be more flexible, the direction to be stronger and the distribution efficiency of the prestressing force beam in vitro to be high.

Description

technical field [0001] The invention relates to a reinforcement method for common defects of prestressed concrete girder bridges, especially suitable for external prestressed reinforcement of common defects such as box-shaped long-span prestressed concrete beams, rigid structures and T-structure bridges, and belongs to fixed structures such as bridges In particular, it relates to an external prestressing reinforcement method for defects such as mid-span deflection and web cracking of prestressed concrete box-section bridges. technical background [0002] Prestressed concrete box girder bridges have been favored by the world bridge engineering community due to their advantages such as wide span adaptability, close stress between construction state and operation state, high system rigidity, stable driving, and small maintenance workload in the later period. Since the 1990s, it has been widely used in countries all over the world, and the maximum span has reached 330m. However...

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Problems solved by technology

The disadvantages of this method are: 1. Due to the inconsistency of shrinkage and creep, the joint work effect of old and new concrete is not ideal; 2. In order to meet the requirements of local anchorage and steering stress, the anchoring tooth plate and steering diaphragm should be relatively strong, while the box The operating space inside the beam is limited, and the construction of a large amount of concrete is difficult, which increases the burden on the original structure, and the reinforcement construction period is long, the amount of work is large, and the traffic on the bridge deck needs to be interrupted; 3. The current distribution method will load the pier top Bending moment, mid-span positive bending moment, and quarter-span web shear resistance are treated equally, while the mid-span section has the smallest section characteristics, the positive bending moment is much smaller than the negative bending moment at the top of the pier, and the shear force is basically zero. The dosage of the external beam is controlled by the compressive stress of the mid-span section, which is far from meeting the requirement of the negative bending moment at the top of the balanced pier; 4. The amount of the external beam is also limited due to the local stress of the anchorage and steering structure and the strength of the original structure concrete.

The above factors make the external beams unable to achieve the ideal reinforcement effect, so many bridges in China have to take load limiting measures

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