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Concrete column strengthening method of compressive pre-stress steel casing rebar planting extension cross section

A technology for reinforced concrete columns and concrete columns, which is applied in the directions of columns, pier columns, and pillars, can solve the problems of excessively long prestressed struts, asynchronous stress between the old and new parts, and reduced lateral stiffness of concrete columns, and achieves the ability to withstand The effect of force synchronization, clear force, and improved energy consumption

Active Publication Date: 2015-05-20
HUNAN INSTITUTE OF ENGINEERING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The erection of the axial struts shared part of the force of the original concrete columns, so that the original concrete columns were partially unloaded. The existing problem was that the forces of the old and new parts were not synchronized, and the prestressed struts were too long or the force was too large. It is laterally reinforced to ensure its lateral stability
The first four reinforcement methods mentioned above can reduce the slenderness ratio of the column and increase the rigidity of the column, while the reinforcement of the axial prestressed strut and the reinforcement of the axial prestressed tie rod may reduce the lateral stiffness of the concrete column

Method used

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  • Concrete column strengthening method of compressive pre-stress steel casing rebar planting extension cross section

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Experimental program
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Effect test

Embodiment 1

[0049] See attached Figure 4-6 , a comprehensive office building, built in the 1980s, has a four-story brick-concrete structure. In 2004, according to the development needs of the unit, the second floor was converted into an archive room. The section size of the original column is 400mm×400mm, and the eccentricity e=500mm. According to the calculation of the new code, its bearing capacity cannot meet the needs, so it is reinforced. The hardening process is as follows:

[0050] The concrete column is strengthened by the method of precompressed stress steel casing and planting bars to expand the section, and the bearing capacity of the reinforced column is checked according to the new code, so as to illustrate the extent of the increase in the bearing capacity of the column after reinforcement.

[0051] Known conditions: C25 concrete, the compressive strength of concrete f c =11.9N / mm 2 , HRB335 rebar, steel bar tensile strength f y =300N / mm 2 , column section dimensions ...

Embodiment 2

[0086] See attached Figure 7 , 8 ,9.

[0087] 1. Current status of reinforced columns: multi-layer frame structure, circular cross-section axial compression column at the bottom, diameter d=500mm, axial force design value N 0 =3900kN, the calculated length of the column is l 0 =6m, column slenderness ratio l 0 / d=6m / 0.5m=12; the concrete strength grade is C30, the longitudinal reinforcement adopts HRB400 grade, the stirrup adopts HRB335 grade, and is welded with the longitudinal reinforcement, C30 concrete f c =14.3N / mm 2 , HRB335 steel bar f yv =300N / mm 2 , f of HRB400 steel bar y '=360N / mm 2 , cylinder with compression longitudinal reinforcement Then the compression longitudinal reinforcement area A s '=1884mm 2 , column core section diameter d cor = 440mm, core cross-sectional area The formula for calculating the bearing capacity of concrete is:

[0088] N≤0.9(f c A cor +f y 'A s '+2αf yv A sso ) (1)

[0089] Take N=N 0 Get the converted cross...

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Abstract

The invention discloses a concrete column strengthening method of a compressive pre-stress steel casing rebar planting extension cross section. The concrete column strengthening method of the compressive pre-stress steel casing rebar planting extension cross section comprises the following steps that a steel casing matched with the shape of a reinforced concrete column is adopted to exert an annular pre-stress on a rebar concrete column, radiation rebar is welded on the outer surface of the steel casing and in perpendicular to the outer surface of the steel casing, an annular stirrup is arranged on the free end of the radiation rebar, longitudinal bars are vertically welded on the interior of the annular stirrup in the axial direction of the reinforced concrete column, finally a template is established outside the annular stirrup, and concrete is casted. According to the concrete column strengthening method of the compressive pre-stress steel casing rebar planting extending cross section, the original concrete column structure is not destructed, the pre-stress is exerted on the original structure, and therefore the force sate of original concrete changes from a two-way pre-stress state to a three-way pre-stress state, the compressive strength of the concrete is improved and then the structure bearing capacity of the reinforced column is improved; the ductility performance of the component is greatly improved, the energy-dissipating capacity is greatly improved, and the structure has the excellent anti-seismic property. The concrete column strengthening method of the compressive pre-stress steel casing rebar planting extension cross section is applicable to reinforcing the concrete component in engineering.

Description

technical field [0001] The invention discloses a concrete column reinforcement method, in particular to a concrete column reinforcement method in which a precompressed stress steel casing is installed and bars are planted to enlarge the section, and belongs to the technical field of concrete construction methods. Background technique [0002] Reinforced concrete structure is the most widely used structural form in engineering practice. There are many reinforced concrete structures that need to be reinforced due to poor construction quality, changes in building use, structural overloading, exposure to harsh environments, etc. Methods of strengthening reinforced concrete columns include: [0003] Increased section reinforcement method. Also known as outsourcing concrete reinforcement method, it is a form of reinforcement that increases the cross-section and reinforcement of components or buildings to improve their strength, stiffness, stability and crack resistance to meet t...

Claims

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Application Information

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IPC IPC(8): E04G23/02E04C3/34
Inventor 任振华曾宪桃
Owner HUNAN INSTITUTE OF ENGINEERING
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