Abstract
This paper examines the experimental performance of ultra-high-performance steel fibre-reinforced concrete (UHPSFRC) beams subjected to loads at relatively low shear span-to-depth ratios. The results and observations from six tests provide a detailed insight into the ultimate response including shear strength and failure mode of structural elements incorporating various fibre contents. The test results showed that a higher fibre content results in an increase in ultimate capacity and some enhancement in terms of ductility. Detailed nonlinear numerical validations and sensitivity studies were also undertaken in order to obtain further insights into the response of UHPSFRC beams, with particular focus on the influence of the shear span-to-depth ratio, fibre content and flexural reinforcement ratio. The parametric investigations showed that a reduction in shear span-to-depth ratio results in an increase in the member capacity, whilst a reduction in the flexural reinforcement ratio produces a lower ultimate capacity and a relatively more flexible response. The test results combined with those from numerical simulations enabled the development of a series of design expressions to estimate the shear strength of such members. Validations were performed against the results in this paper, as well as against a collated database from previous experimental studies.
Highlights
Ultra-high-performance concrete (UHPC) exceeds the performance of normal or high-strength concrete, allowing for the construction of more slender and efficient reinforced concrete (RC) structures
This paper presents a study into the response of ultra-high-performance steel fibre-reinforced concrete (UHPSFRC) materials and elements through a series of compressive and flexural tests on cubic and prismatic samples, respectively, as well as on medium-scale I-beams provided with conventional longitudinal reinforcement and various steel fibre contents
The following section introduces a method to assess the shear strength of UHPSFRC members subjected to concentrated loads in the vicinity of the support with shear span-to-depth ratios below a/d < 2.5, using the results and observations from the tests described in Sect. 2 and numerical simulations in Sect. 3, as well as the results of a collated data set tests from the literature [46,47,48,49,50,51]
Summary
Ultra-high-performance concrete (UHPC) exceeds the performance of normal or high-strength concrete, allowing for the construction of more slender and efficient reinforced concrete (RC) structures. This is achieved using ultrafine constituents and reactive powders which improve the mechanical properties and durability, yet increases the brittleness [1, 2]. For enhancement of the ductility properties, steel fibres are attractive as concrete constituents [2,3,4] These can contribute to reducing the amount and congestion of conventional reinforcement in RC elements [4, 5] and are widely used in practice in tunnel linings, industrial floor slabs and aircraft runways.
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