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The steel-strapping tensioning technique (SSTT) has been widely accepted as an effective method for enhancing the performance of high-strength concrete (HSC) columns. Previous experimental tests showed that SSTT can increase the ductility of HSC by up to twice that of unconfined HSC. However, most of the tests performed on SSTT-confined HSC columns have focused on concentrically loaded short specimens. In reality, however, columns with a length/diameter ratio greater than three and subjected to eccentric loading are very common. Against this background, experiments were carried out to investigate the slenderness effect of SSTT-confined HSC columns subjected to eccentric loads. It was found that SSTT increases both the strength and deformability of slender HSC columns, although the confining effects are reduced proportionally with an increase in slenderness ratio. The effects of the eccentricities and the eccentricity ratio are also presented in this paper.

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This study examines the flexural behaviour of high‐strength concrete (HSC) beams confined using an innovative steel strapping tensioning technique (SSTT) able to provide active confinement. Twelve over‐reinforced HSC beams (fc = 50 or 80 MPa) were designed to fail prematurely by concrete crushing at mid‐span. The mid‐span region of eight such beams was confined externally using the SSTT with different steel strap confinement ratios, the aim of which was to delay concrete crushing. The test results are discussed in terms of the failure modes, load‐deflection response and the concrete and tensile reinforcement strains observed. Although the unconfined beams failed in a brittle manner with no post‐peak deflection, the steel straps were very effective at enhancing the post‐peak deformation of the SSTT‐confined beams by up to 126 %. Moreover, for the beams tested in this study, the use of the SSTT led to failures after yielding of the tensile reinforcement. The proposed SSTT can be used to confine HSC elements where ductility is required.

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An experimental and analytical study on the application of Steel Strapping Tensioning Technique (SSTT) confinement on twelve high-strength concrete cylinder specimens with dimension of 100 mm and 200 mm in diameter and height respectively has been studied and presented throughout this paper. The specimens were volumetric-identically confined with two different confining materials of different mechanical properties and lateral pre-tensioning stresses, namely SSTT(HC) and SSTT(SS). All concrete specimens were tested under uniaxial compression load. The performance of SSTT-type confined specimens were studied through their stress-strain relationship upon the longitudinal and transverse deformation, mode of failure, level of lateral pre-tensioning stress, and dilatancy behaviour. The results show that high-strength concretes confined with SSTT would significantly reduce the brittleness problem and at the same time, enhancing both ultimate compressive strength and ductility up to 65% and 344%, 36% and 269% for both SSTT(HC) and SSTT(SS), respectively. Those specimens confined with higher lateral pre-tensioning stress exhibits smaller radial expansion and higher rate of axial strain, able to slow down the dilation of confined specimens under loading and thus, helps in enhancing the compressive capacity and ductility. In addition, an analytical comparison between SSTT-type confinement and conventional confinement models have been presented and the results show a linear relationship between the compressive strength enhancement and confinement ratio. Current experimental results were also validated by comparing the observed stress-strain relationship proposed by Mander.