PSI - Issue 17

B. Moussaoui et al. / Procedia Structural Integrity 17 (2019) 979–985 B.Moussaoui & Y.Bouamra & K.Ait tahar & al./ Structural Integrity Procedia 00 (2019) 000 – 000

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[3,5,16,17,19,21]. Actually, more researches focused on FRP-confine columns [11-15] concluded that the confinement increased the strength and ductility of the columns. Failure of FRP-confined concrete columns is governing by FRP rupture. This phenomenon has been observing by many studies conducted on FRP confined circular concrete cylinders [9, 17]. In addition, several studies confirmed that FE models could be using successfully to simulate the Behavior of concrete cylinders confined by FRP composites. All researchers reported that an increase in lateral pressure leads to significant increase in ductility and strength, and reduces internal cracking. In this work, this study is carried out to investigate the behavior of partially confined cylinders ‘PCC’ with GFRP composites subjected to axial compressive loads and a finite element (FE) software is using to simulate the behavior of partially and fully confined cylinders. Three configurations of confined cylinders are studied. The objective herein is to evaluate the effectiveness of partial confining on the behavior of the concrete cylinders. The influence of parameter x/h (ratio of the height of the confined area on the full height of cylinder) on the behavior of partially and fully wrapped with GFRP composites concrete cylinders under axial compressive load is studied. The results indicated an increase in ultimate strength and ductility as the x/h ratio was increased, and showed that had influence on the confined fc – εc relationship. It was observe that depending on the ratio x/h, the strength and ductility increments would vary. Comparison of the results generated using the model with FE and experimental results are in good agreement. 2. Experimental program and Test specimens 2.1. Materials used, detailing of specimens and test procedure All the cylinders of dimensions 160x320 mm were carried out with only one composition of aggregates. A conventional rotary drum concrete mix was used, followed by a slump test according to EN12350-2 standards. The specimens have been made according to Eurocode2, by mixing CPJ Portland cement CIMATCEM II /A-L 42.5 R., aggregate with maximum diameter (3/8) and (8/15), natural sand, water and superplasticizers. The concrete composition was determined according to the method of Dreux-Gorisse. Three standard cylinders for each specimen’s configurations were casted from each batch to prepare the test loading. Three unconfined specimens were used for comparison purposes. The specimen was cured in saturated limewater for 28 days until testing. The 28-day compressive strength of the used UC concrete was found to be 24.5 MPa. The composite Jacket is made up of E fibers- reinforced polymer ‘GFRP’. The yield strength and the Young’s modulus of elasticity of the GFRP provided by the manufacturer are respectively 1 400MPa and 72 GPa. The preparation of the substrate surface was done when the concrete specimen was 24 days old. Before the reinforced of specimens by one (01) layer GFRP composite materials, a layer of 1mm of the resin SIKA DUR-330 epoxy was applied on the contact surfaces of the treated substrate concrete of specimens as shown in Fig. 1.

Fig. 1. Confined concrete test specimens and manufacturing