International Journal of Civil and Structural Engineering Research ISSN 2348-7607 (Online) Vol. 9, Issue 2, pp: (68-75), Month: October 2021 - March 2022, Available at: www.researchpublish.com
Behavior of Encased Composite Concrete Columns under Fire Exposure Mohammed E. Elghobary1, Ahmed Bakhit2, Fouad Khairallah3, Hala Mamdouh4 1
M.Sc. student, Department of Civil Engineering, Helwan University, Cairo, Egypt. E-mail:mohamed.elsayed311912@gmail.com 2
Professor of Structural Engineering, Bni Swef University, Egypt. E-mail:Ahmedhb96@yahoo.com
3
Assoc. Professor of Structural Engineering, Helwan University, Cairo, Egypt. E-mail:fouad.khair@gmail.com
4
Assoc. Professor of Structural Engineering, Helwan University, Cairo, Egypt. E-mail:dr_hala_mamdoh@yahoo.com
Abstract: Composite column systems have become popular in tall building construction due to combining the rigidity and formability of reinforced concrete with the strength, ductility, and speed of construction of structural steel to produce an economic structure. This paper presents an experimental study to get more knowledge about the characteristics and the fire resistance of encased composite concrete columns. Three-scale three reinforced composite concrete columns were constructed and tested up to failure under direct fire at 500◦C for two hours. The experimental program Consists of three specimens with 150 mm in diameter and 1500 mm in height, C 500 -up section have 7 gaps with a diameter of 5cm at the section web, the second specimen (CIB 500 5 C 500 -up section has 14 welded metal plate. The performance of the tested composite columns specimens is evaluated based on the crack pattern, first crack, failure load, ductility. Moreover, the experimental results are shown a proportional relationship between the degree of temperature and residual strength, causing the residual strength to decrease by 18.29 %. The result shows that the failure load for the encased composite column by plates (CIP 500 column) was much greater than the loadcarrying capacity of other composite columns, this is due to the high capacity of steel material which is found inside the column. After exposure to a g 500 ◦ C ws that the failure load is higher than the failure load for the encased composite column by gaps and bolts by 29.7% and 8.17% respectively. Keywords: encased composite; concrete columns; fire exposure; civil engineering.
1. INTRODUCTION Composite structures represent an ideal alternative to typical engineering materials, this is due to the high demand for using more modern construction materials by using lightweight and high-strength structures. Composite column systems have become popular in tall building construction due to combining the rigidity and formability of reinforced concrete with the strength, ductility, and speed of construction of structural steel to produce an economic structure. Further axial compression of the structure leads directly to the phenomenon of loss of stability (buckling) [1]. Generally, failure is interpreted as the loss of the effective cross-sectional area of a structure due to micro-cracks [2-3]. The advantages of composite columns are increased stiffness, leading to reduced slenderness and increased buckling resistance, good fire resistance, corrosion protection in encased columns, significant economic advantages over either pure structural steel or
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