Strengthening method for armoured concrete slab

Abstract

The invention relates to a strengthening method for an armoured concrete slab. In the method, a permanent mechanical anchor device is adopted to install a cable in a pulled area of a strengthened armoured concrete slab; after anchoring, the strengthened armoured concrete slab is used as a counter-force device to transversely stretch the cable, apply prestress to the cable and fix the cable, and polymer mortar is coated to cover the whole anchor device and the cable. The method has the advantages that the cable is in a tensioning state, is solid and firm after being subjected to stretching andprestress by the easy permanent mechanical anchoring without any auxiliary anchoring components and complex structures; a transverse stretching method is adopted to apply prestress to the cable, thereby not only overcoming the problem of lagged stress of high-strength materials but also being convenient to realize in the strengthening site and achieving the advantages of simple and convenient operation and low cost; the method has two-way prestress effect, thereby being particularly suitable for a condition that longitudinal crack occurs to a prestress cored slab in a strengthening bridge structure, and effectively solving the problem of longitudinal crack strengthening of the prestress cored slab in bridge engineering.

Description

technical field [0001] The invention relates to a building reinforcement method, in particular to a reinforcement method for a reinforced concrete slab. Background technique [0002] The reinforcement method for reinforced concrete slabs used in the prior art is the high-strength steel strand-polymer mortar reinforcement technology. It lays the steel hinge wire mesh on the tensile area of ​​the reinforced member, and coats the polymer mortar on its surface. Among them, the steel hinge is the main body of the force, and its tensile strength is higher than that of ordinary steel bars in the reinforced structure; the thickness of the polymer mortar surface layer is generally 25-50mm, and it protects the steel hinge mesh on the one hand. At the same time, it is bonded to the original structure to form a whole, so that the steel hinge mesh and the original structure work together. The main drawbacks of this technique are: [0003] (1) The strength of high-strength steel strand...

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Problems solved by technology

[0003] (1) The strength of high-strength steel strand (wire rope) is as high as 1500-1600MPa, but the elastic modulus is low (about 1.1-1.5×10 5 MPa, common steel is about 2.1×10 5 MPa), as the post-added material of the structure, the material will play a role only after the structure is further loaded and the deformation increases, and its stress hysteresis is serious. Even if the structure is unloaded, the stress level is still very low under normal working conditions. Only about 100-150MPa, the strength of the material cannot be fully utilized, and the reinforcement efficiency is low;

[0004] (2) The post-added material is passively stressed and cannot realize the unloading effect on the original structure. The stress level is not coordinated with the original structure. The original structure may still be in a high stress state, and it is easy to be broken by each in the limit state. The seismic performance of the structure is unfavorable;

[0005] (3) This reinforcement method cannot realize the active repair and closure function of cracks, and has limited effect on restoring the original structure;

[0006] (4) In order to ensure the anchorage of the steel strand and prevent the stripping of the reinforcement layer, the construction measures adopted are complicated, which increases the cost;

[0007] (5) The force transmission of the high-strength steel strand mainly depends on the polymer mortar. The interface stress between the polymer mortar and the concrete component and the bonding stress level between the high-strength steel strand and the polymer mortar are relatively high. and construction requirements are high, not only the cost is high, but the reliability is relatively poor

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