Steel Jacketing Technique used in Strengthening Reinforced Concrete Rectangular Columns under Eccentricity for Practical Design Applications
|International Journal of Engineering Trends and Technology (IJETT)||
|© 2016 by IJETT Journal|
|Year of Publication : 2016|
|Authors : Ezz-Eldeen, H. A.
|DOI : 10.14445/22315381/IJETT-V35P243|
Ezz-Eldeen, H. A."Steel Jacketing Technique used in Strengthening Reinforced Concrete Rectangular Columns under Eccentricity for Practical Design Applications", International Journal of Engineering Trends and Technology (IJETT), V35(5),195-204 May 2016. ISSN:2231-5381. www.ijettjournal.org. published by seventh sense research group
In the present study, the steel jacketing technique with variable vertical angles size connected with horizontal steel straps is used to upgrade the load carrying capacity of rectangular reinforced concrete columns under eccentric loads. Seventeen reinforced concrete rectangular columns were loaded and tested under different eccentricities until failure. Each column has 120x160 mm cross section and 1000 mm length with four normal mild steel bars 8 mm diameter as a vertical reinforcement and 6 mm diameter horizontal normal mild steel ( stirrups ) with 120 mm spacing. Five columns nonstrengthened were tested under different eccentricities (e/t = 0, 6.25 %, 12.50 %, 18.75 % and 25.00 %) as control columns. However, twelve columns were divided into three groups strengthened with two external angles 20x20x2 mm, 40x40x2 mm and 60x60x2 mm in compression side respectively and two external angles 20x20x2 mm in tension side for all strengthened columns. The strengthened columns were tested under different eccentricities (e/t = 6.25 %, 12.50 %, 18.75 % and 25.00 %). Numerical analysis using the finite element technique has been conducted to simulate the response of control and strengthened columns. A finite element commercial package "ANSYS version 15" is used in the present analysis. The results of the finite element model have fair agreement with the experimental results. The validated finite element model was used to conduct parametric analysis for practical design applications. Columns with cross sectional areas ranging from (25x30) cm to (25x120) cm; strengthened with different angles size subjected to eccentricity (e/t) 10% , 20% and 30% were investigated. The columns were 300 cm in height and have vertical reinforcement 1 % of the concrete cross sectional area; 8 mm stirrups spaced at 20 cm were provided for all columns. The columns were strengthened using 2 vertical angles of different size in tension side and 2 vertical angles of different size in compression side welded by horizontal straps 50 cm apart. The dimensions and thicknesses of the angles were identified for each column according the needed level of strengthening. Each column is strengthened to reach the original column carrying capacity. The results showed that increasing the covered area of the steel jacket as well as increasing cross sectional area of the steel angles increases the load carrying capacity of the strengthened columns. The relationships between the strengthened columns and the corresponding dimensions of the angles are presented in tables for practical applications.
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Column, Eccentricity, Practical Design Applications, Reinforced Concrete, Steel Jacket, Strengthening.