Abstract
This paper studies the behavior of axially loaded RC columns which are confined with carbon fiber reinforced polymers’ sheet (CFRP) and steel jackets (SJ). The study is based on twelve axially loaded RC columns tested up to failure. It is divided into three schemes based on its strengthening type; each scheme has four columns. The main parameters in this study were the compressive strength of the concrete and steel reinforcement ratio. Furthermore, the results of the experimental test showed a substantial enhancement in the column's load-carrying capacity. When compared to the original columns, the CFRP sheet had a significant effect on improving the ductility of the column by increasing the axial deformation by about 59.2 to 95.7%. On the other hand, the SJ contributed mostly to the column load-carrying capacity, which increased the capacity of RC concrete from 75 to 107%; because of its composite action comparing with the CFRP sheet action in which unidirectional lateral confinement is provided. Both methods produced completely different failure modes. The columns strengthened with CFRP sheet failed by rupture occurring in the sheet fibers. The strengthened with SJ failed due to the buckling that occurred in the steel angles due to the direct contact with the head of the column, and crushing in the concrete has occurred.
Highlights
Columns are compression members and are the most important structural members
The carbon fiber reinforced polymers’ sheet (CFRP) has been widely used in externally strengthening for different structural members such as beams, columns, and slabs [4]
The CFRP jacket provides the RC columns with passive confinement and is stressed only when an additional axial load is applied to a column that causes dilation
Summary
Columns are compression members and are the most important structural members. Their failure can lead to a total collapse of the building. The investigation of carbon fiber reinforced polymer was thoroughly examined by many researchers [6,7,8,9] They studied the effect of corner roundness, the column height, the cross-section shape, the number of layers, and the method of wrapping (partially or complete) on the strength and ductility of the RC column. Work Plan: Laboratory work is accomplished by casting 12 columns divided into four groups and three schemes, the groups divided according to two parameters; concrete compressive strength (24.2 and 31.7 MPa) and reinforcement steel ratio (1.4 and 2%) According to these parameters, there are three columns of different types of strengthening (without strengthening as a reference specimen, strengthening with CFRP, and strengthening with steel jacket). The gradient of nominal aggregate was accepted according to IQS NO. (1980) [16]
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