Axial Behaviour of Slender RC Circular Columns Strengthened with Circular CFST Jackets

Abstract

is paper investigates the axial behavior of slender reinforced concrete (RC) columns strengthened with concrete filled steel tube (CFST) jacketing technique. It is realized by pouring self-compacting concrete (SCC) into the gap between inner original slender RC columns and outer steel tubes. Nine specimens were prepared and tested to failure under axial compression: a control specimen without strengthening and eight specimens with heights ranging between 1240 and 2140 mm strengthened with CFST jacketing. Experimental variables included four different length-to-diameter (L/D) ratios, three different diameter-to-thickness (D/t) ratios, and three different SCC strengths. e experimental results showed that the outer steel tube provided confinement to the SCC and original slender RC columns and thus effectively improved the behavior of slender RC columns. e failure mode of slender RC columns was changed from brittle failure (concrete peel-off) into ductile failure (global bending) after strengthening. And, the load-bearing capacity, material utilization, and ductility of slender RC columns were significantly enhanced. e strengthening effect of CFST jacketing decreased with the increase of L/D ratio and D/t ratio but showed little variation with higher SCC strength. An existing expression of load-bearing capacity for traditional CFST columns was extended to propose a formula for the load-bearing capacity of CFST jacketed columns, and the predictions showed good agreement with the experimental results. Recently, a novel technique, CFST jacketing, has become an option to strengthen concrete columns because of the superior performance of CFST columns (e.g., high loadbearing capacity and good ductility). It has been successfully applied in the strengthening of RC bridge piers [20,21]. CFST jacketing is realized by the installation of in-field welded steel tube around the original RC column and

Behavior of an Innovative Square Composite Column Made of Four Steel Tubes at the Corners and Corrugated Steel Batten Plates on all Sides

“…e eight-node reduced integration linear solid elements with three translation degrees of freedom (C3D8R) were utilised for modelling the steel tube, corrugated steel plate, concrete and loading plates [1][2][3][4]. Obviously, the thin-walled steel tube used in the ISSCC column buckles locally outwards with the extrusion provided by the filled concrete.…”

“…e CFST column composes of an empty steel tube filled with concrete, at which both materials sustain together the applied axial load. In recent years, CFST column has widely been used in various building structures and bridges due to good mechanical properties and construction performance [1][2][3][4].…”

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“…Ren and Chen et al 17,18 analyzed the full range bearing performance and failure characteristics of fully grouted bolts based on the tri-linear bond-slip model of the anchorage interface. Lu and Wang et al [19][20][21] used an improved tri-linear bond-slip model of the anchorage interface to analyze the pullout bearing properties of fully grouted bolts. Jiang and Song et al 22,23 used FLAC3D numerical software to study the pullout bearing characteristics of fully grouted bolts.…”

Axial behaviour of slender concrete-filled steel tube square columns strengthened with square concrete-filled steel tube jackets

“…However, the studies about CFST jacketing strengthening mostly focus on the RC columns (Li et al, 2019;Lu et al, 2016Lu et al, , 2018. These previous investigations on the behaviour of stub and slender RC columns strengthened by CFST jacketing showed that all retrofitted specimens behaved in a ductile manner with the load-bearing capacity and ductility significantly enhanced.…”