Analysis of strengthened short deficient rubberized concrete-filled steel tubular columns

Suzan Mustafa,Fady Elshazly,Hesham Fawzy

doi:10.3221/igf-esis.55.01

Abstract

Concrete-filled steel tubular (CFST) columns are broadly used in many structural systems for their well-known merits. This paper presents a finite element investigation on the structural behaviour of short circular deficient steel tubes filled with rubberized concrete (RuC), under axial compressive load. To accomplish this study, a validation of the proposed three-dimensional nonlinear finite element model; using ANSYS software; was carried out showing good accurateness. The analysis involved two different concrete mixes with 5% and 15% replacement of fine aggregate volume with crumb rubber particles. Columns strength reduction due to horizontal or vertical deficiencies was handled by increasing the thickness of the steel tube or wrapping the columns with two different types of FRP sheets. Five strengthening arrangements were studied using GFRP sheets and CFRP sheets. The results indicated that the ultimate bearing capacity of the RuCFST columns was increased with increasing the steel tube thickness. application of FRP sheets for strengthening the deficient RuCFST columns efficiently managed to retrieve the strength-lost due to either horizontal or vertical deficiency. Moreover, an enhancement in the columns’ ductility was observed especially when using GFRP sheets

Highlights

Structural engineering witness high rate of progress accompanied with high ambition to get the most benefit of all members consisting the structure
Prabhu and Sundarraja [5] studied experimentally and analytically the effect of strengthening Concrete Filled Steel Tube (CFST) using Carbon Fiber Reinforced Polymers (CFRP) strips under compressive load. They strengthened the specimens using transversal CFRP strips. They outlined that CFRP strips using in external wrapping of CFST specimens was effective in delaying the local buckling of the CFST specimens
Prabhu et al [6] agreed with the previous results of Prabhu and and Sundarraja [5]. They [6] figured out that confinement was enhanced with the increase in CFRP layers. They proposed that using CFRP strips in strengthening of CFST columns at spacing of 20 mm or 30 mm would be so effective

Summary

INTRODUCTION

Structural engineering witness high rate of progress accompanied with high ambition to get the most benefit of all members consisting the structure. Sundarraja and Prabhu [2] studied experimentally the behavior of steel tubes filled with concrete and partially wrapped with Carbon Fiber Reinforced Polymers (CFRP) under axial compressive loads They showed that CFRP provided effective confinement, delayed local buckling occurrence, and increased ultimate bearing capacity in agreement with the results of Lu et al [3] and the experimental and numerical results of Shen et al [4]. Dong et al [21] studied rubberized CFST (RuCFST) to investigate the effect of confinement provided by the steel tube to the RuC core on specimens’ ductility and strength They proposed that rubber existence in concrete caused strength decrease and ductility increase of the concrete mix. AGeneral three-dimensional nonlinear finite element model was proposed to investigate the behavior of deficient short RuCFST columns under axial compressive load Some of these columns were strengthened using FRP sheets.

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Findings

CONCLUSION