2019 CSCE Annual Conference - Laval (Greater Montreal)

2019 CSCE Annual Conference - Laval (Greater Montreal) Conference

Effectiveness of concrete filled steel jackets for RC columns

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Mr. Saadeldin Mostafa (Presenter)
Dr. Mohamed N. Abou-Zeid, The American University in Cairo


Repair and strengthening techniques of RC elements are considered to be challenging due to time, cost, and space constraints. Conventionally, several techniques have been used in the retrofitting of RC element. These techniques includes epoxy repair, concrete and steel jacketing and FRP. Recently a new technique has been introduced in some cases which is concrete filled steel jackets. Although the previously mentioned techniques have been thoroughly studied, this technique has not been studied in literature. Consequently, more data is required for a safe and economic design of this technique.

In this work, a repair/strengthening technique for RC columns is proposed which is concrete filled steel jackets. This technique comprises a steel cage consisting of four steel angles with steel strips at fixed spacing to prevent the buckling of the angles. The space between the RC column and the steel cage is filled with different classes of concrete.

The experimental program consisted of ten RC columns, two of them are unstrengthened columns. Eight steel cages were used with the same length of the column to confine the RC columns. Four different concrete mixes of filling concrete were prepared with different grades to be used as the filling concrete. No interface or shear connectors were used between the old and new filling concrete. LVDTs and strain gages were mounted on the specimens to record the load displacement and stress strain curves of the specimens. The properties of hardened concrete mixes were assessed using their cube strength at 28 days. The specimens were then uniaxially loaded till failure. Afterwards, the results of jacketed specimens were compared with each other as well as control specimens (i.e. specimens without jacketing). 

In order to address the effect of the composite jacketing, the strength of the columns are to be compared with the Eurocode 4 design equations for composite sections. It is expected that this work will achieve a better understanding of the behavior of this composite system in terms of strength and ductility.  As well as exploring the most appropriate concrete class to be used with this proposed technique.