Concrete-filled square steel tubular column reinforcing method based on high-ductility cement-based material

Abstract

The invention provides a concrete-filled square steel tubular column reinforcing method based on a high-ductility cement-based material. The concrete-filled square steel tubular column reinforcing method comprises the steps that first reinforcing pieces and second reinforcing pieces are fixed to four corners of a concrete-filled square steel tubular column; a plurality of steel strands are uniformly wound on the concrete-filled square steel tubular column at certain intervals from top to bottom and fixed on the second reinforcing pieces, and a steel strand net is formed; prestress is applied to each steel strand; and a high-ductility cement-based material layer is formed on one surface of the concrete-filled square steel tubular column through spray-coating and smearing, the high-ductilitycement-based material layer covers the first reinforcing pieces, the second reinforcing pieces and the multiple steel strands, gaps are filled, and reinforcing is completed. The weight ratios of thecomponents in the high-ductility cement-based material to cement are as followings: fly ash: 0.5-3, fine sand: 0.5-1.5, silica fume: 0-0.1, water: 0.5-2, PVA fiber: 0.02-0.1, a water reducing agent: 0.005-0.02, and a setting accelerator: 0.01-0.1. The method has the advantages that high temperature resistance is achieved, construction is simple and convenient, the expanded section area is relatively small, and the building area is not occupied.

Description

technical field [0001] The invention relates to the field of building construction, in particular to a method for strengthening a square steel tube concrete column based on a high-ductility cement-based material. Background technique [0002] The concrete-filled steel tube column has the characteristics of high strength, good ductility, fatigue resistance and impact resistance. Its outer steel tube can have a strong restraint effect on the inner core concrete. When it is under compression, the concrete is in three compression states, and its strength is greatly improved. The steel pipe can replace the role of the steel bar, and there is no need for reinforcement in the concrete. During construction, the steel pipe can be directly used as a template for concrete pouring, which greatly saves construction cost and time. In addition, the internally filled core concrete retards local buckling of steel pipes. Based on the above advantages, CFST columns have been widely used in t...

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Problems solved by technology

The FRP reinforcement method is to use light and high-strength materials such as carbon fiber cloth and glass fiber cloth, combined with epoxy resin glue, and wrap them on the surface of the column to play a role of circumferential restraint and improve the bearing capacity of the reinforced column. However, this reinforcement method is limited. Due to the poor high temperature resistance and fire resistance of epoxy resin glue, the glass transition temperature of epoxy resin glue is generally 50-80°C. When the ambient temperature exceeds the glass transition temperature, epoxy resin glue will fail, and FRP will lose its The foundation of the joint action of steel tube concrete columns cannot play its role; the method of enlarging the cross-section is to pour a new layer of reinforced concrete reinforcement outside the original column. This method can greatly increase the bearing capacity of the reinforced column, and the construction is simple. However, its disadvantage is that the enlarged cross-sectional area is relatively large, and the building area is occupied.

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