Flexural Strength of Internally Stiffened Tubular Steel Beam Filled with Recycled Concrete Materials.

Ahmed W Al Zand,Riyadh Al-Ameri,Mustafa M Ali,Wan Hamidon Wan Badaruzzaman,Zaher Mundher Yaseen,Emad Hosseinpour,Wadhah M Tawfeeq

doi:10.3390/ma14216334

Abstract

The flexural strength of Slender steel tube sections is known to achieve significant improvements upon being filled with concrete material; however, this section is more likely to fail due to buckling under compression stresses. This study investigates the flexural behavior of a Slender steel tube beam that was produced by connecting two pieces of C-sections and was filled with recycled-aggregate concrete materials (CFST beam). The C-section’s lips behaved as internal stiffeners for the CFST beam’s cross-section. A static flexural test was conducted on five large scale specimens, including one specimen that was tested without concrete material (hollow specimen). The ABAQUS software was also employed for the simulation and non-linear analysis of an additional 20 CFST models in order to further investigate the effects of varied parameters that were not tested experimentally. The numerical model was able to adequately verify the flexural behavior and failure mode of the corresponding tested specimen, with an overestimation of the flexural strength capacity of about 3.1%. Generally, the study confirmed the validity of using the tubular C-sections in the CFST beam concept, and their lips (internal stiffeners) led to significant improvements in the flexural strength, stiffness, and energy absorption index. Moreover, a new analytical method was developed to specifically predict the bending (flexural) strength capacity of the internally stiffened CFST beams with steel stiffeners, which was well-aligned with the results derived from the current investigation and with those obtained by others.

Highlights

Introduction iationsThe usefulness of various types of concrete-filled steel tube (CFST) has been proven in modern composite structural projects since they have achieved better performances than the corresponding conventional concrete/steel members under axial and flexural loading [1,2,3,4]
This study aimed to develop a new analytical method that can theoretically predict the flexural strength capacity of the internally stiffened CFST beam’s cross-section with varied numbers/sizes of steel stiffeners; this constitutes one of the main novelties of the current research work
The experimental investigation confirmed that the bending capacity of the suggested prefabricated Slender CFST beams made from two pieces of C-sections was enhanced by about 3.7 times even when filled with 70% replacement recycled concrete material

Summary

Introduction

Introduction iationsThe usefulness of various types of concrete-filled steel tube (CFST) has been proven in modern composite structural projects since they have achieved better performances (in terms of strength, ductility and stiffness) than the corresponding conventional concrete/steel members under axial and flexural loading [1,2,3,4]. Internal steel stiffeners were provided to delay and restrict the outward tube’s buckling of the Slender CFST beams’ cross-section [18,19,20,21]. Al Zand et al [19] experimentally and numerically examined the effect of using varied shapes of internal steel stiffeners that were welded along all sides of high-slenderness coldformed square CFST beams. Their investigation showed that these CFST beams’ flexural stiffnesses and strength capacities were improved by about 22–29% when a single stiffener was welded along each tube’s internal sides, and these values were increased by a further

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