Experimental Investigation on the Axially Loaded Performance of Notched Hexagonal Concrete-Filled Steel Tube (CFST) Column

Jing Liu,Zhe Li,Fa-Xing Ding

doi:10.1155/2019/2612536

Abstract

This study aimed to investigate the static performance of notched hexagonal concrete-filled steel tube (CFST) stub columns through axial loading. Notch length, notch location, and notch direction in 14 CFST stub columns were experimentally studied. Stress process, failure mechanism, and ultimate strength in the notched CFST columns were analyzed. Results show that notches in steel tubes can weaken the restraining effect of steel pipes on core concrete and induce a decrease in the ultimate strength of specimens. The failure mode of components is greatly affected by notch orientation. The notch is closed under axial compression in the horizontally notched specimen, and the slotting indicates outward buckling in the vertically notched specimen. Based on the test results, a method for calculating the ultimate strength of notched hexagonal CFST columns was established. This research encourages the extensive application of these structures in civil engineering.

Highlights

Concrete-filled steel tube columns are extensively used in engineering due to their simple joint structures, convenient connections, and excellent flexural behavior
(1) As with other metal structures, initial geometric and material defects exist in the external steel pipes of concrete-filled steel tube (CFST) members, and CFST columns are inevitably affected by corrosion and other external loads upon use [1]. (2) In some engineering projects, such as those involving the connection of steel with a concrete composite beam and CFST column joints, notches must be cut onto the steel pipe. is method weakens the restraint effect of steel pipe on the core concrete at the joints
(2) Chang et al [10] and Ding et al [11] carried out axial compression performance tests on circular or square CFST columns with defects. ey proposed the ultimate bearing capacity calculation formula, which is based on experimental data fitting, for such components

Summary

Introduction

Concrete-filled steel tube columns are extensively used in engineering due to their simple joint structures, convenient connections, and excellent flexural behavior. (1) As with other metal structures, initial geometric and material defects exist in the external steel pipes of CFST members, and CFST columns are inevitably affected by corrosion and other external loads upon use [1]. (1) Regarding the geometric and material defects of CFST columns, Nia et al [6] investigated the influence of initial buckling on the mechanical performance of a square steel pipe under oblique loading. Liu and Young [12] studied the effect of buckling on steel square hollow section compression members and analyzed the strength of the test column with three different. Ding et al [15] investigated the composite action of notched circular CFST stub columns under axial compression through numerical and theoretical studies and presented an empirical formula to predict their ultimate capacity. E present work focused on the static performance of notched hexagonal CFST columns based on our team’s previous research [11, 15, 17]. e objectives were as follows: (1) to experimentally study 14 CFST stub columns and their parameters, including notch length, notch location, and notch direction and (2) to establish a method for calculating the ultimate strength of notched hexagonal CFST stub columns

Experimental Study

Calculation of the Ultimate Bearing Capacity of Notched CFST Columns

Conclusions