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Relatively few studies have explored the shear behavior of concrete deep I-beams. This study presents a series of 12 shear tests on concrete deep I-beams with shear span-to-height ratios (av/h) of 1.0 and 1.5. The effects of horizontal and transverse web reinforcement on structural deformation and shear strength are compared. The findings indicate that a minimum horizontal and transverse reinforcement ratio (ρv=ρh=0.28%) significantly enhances the shear capacity. Additionally, an increase in vertical reinforcement (ρv=1.26%) shifts the failure mode from shear tension to web crushing. Increasing horizontal web reinforcement has little influence on shear capacity at av/h=1.5 , while it significantly enhances strength at av/h=1.0. The upper limit of shear strength for deep I-beams, as specified by ACI 318-19, appears conservative; a limit of 0.225fc′bwd is recommended. The Strut-and-Tie Model (STM) used in ACI 318-19 is conservative, demonstrating an average experimental-to-predicted shear strength value, Vexp/Vpred=3.24 , with a standard deviation of 0.63. Conversely, VecTor2 exhibits an average Vexp/Vpred of 1.07, with a standard deviation of 0.10. The panel element-based model, such as Mau's model, is proven suitable for the analysis of deep I-beams. [ABSTRACT FROM AUTHOR]

Subjected to either tensile or compressive loads, concrete is susceptible to the effect of sustained loading. To address this, common practice in building guidelines typically involves applying a sustained loading factor ranging from 0.6 to 0.85. Given that the shear capacity of structural members without shear reinforcement is linked to the concrete strength, one might question whether there is a comparable sustained loading impact on shear. To address this inquiry, a total of 18 reinforced concrete beams without shear reinforcement were subjected to prolonged sustained loading, with a load intensity factor (ratio of applied sustained shear load to short-term shear resistance) ranging from 0.88 to 0.98. Several beams endured the sustained loading test for an extended period, close to a decade, before the test was terminated. Interestingly, in contrast to concrete subjected to direct compression or tension, it was observed that sustained loading did not affect the shear capacity. Some early results of this experimental study, where concrete beams were subjected to up to 4 years of sustained loading, have been previously published by Sarkhosh and Sarkhosh et al. This paper concludes the results of the testing campaign of up to a decade of sustained loading, with additional results and findings. [ABSTRACT FROM AUTHOR]

Soils used in putting green applications are designed to move water quickly through the profile yet are still able to support turfgrass growth. North American turfgrass horse racing surfaces often use similar soils which are reinforced with synthetic fibers to achieve both high infiltration rates and high shear strength. Natural fibers, in particular jute and sisal, are a promising and more environmentally benign method of increasing the shear strength of soils. The purpose of this study was to submit unreinforced and reinforced golf course soil with synthetic and natural fibers to triaxial shear testing for potential use in Thoroughbred racetracks. Laser diffraction particle size analysis was used to characterize the texture. Bulk density testing was used to determine the moisture content at which peak bulk density occurs. Triaxial shear analysis was then conducted on the soil with the three different types of reinforcement at a moisture content above and below the peak bulk density value. Synthetic fiber reinforcement produced a 10% increase in friction angle and nearly a 50% reduction in cohesion. Both are beneficial improvements for the turfgrass Thoroughbred racing application. Natural fibers produced a comparable change in both friction and cohesion although moisture has an inverse relationship to friction angle. Natural fibers appear to be well suited for divot repair mixes and newly established turf courses. Future research is needed to understand the life span of natural fibers in the soil profile as well as their impact on surface hardness. [ABSTRACT FROM AUTHOR]

The structural use of fibre-reinforced concrete (FRC) has shown to be an attractive alternative for certain structural elements, being especially suitable to withstand shear stresses in concrete beams. In the case of longitudinal steel bars to support bending stresses, the reductions are of interest. However, in the case of shear stress, it is possible to eliminate the stirrup reinforcement in certain areas. In such a case, the use of FRC may eliminate not only the material but also the tasks of preparing and placing reinforcement, achieving significant savings in labour and allowing a faster execution, avoiding human error, and providing greater security to the work. This study was developed with the aim of assessing a basic practical application of FRC for shear strength. A series of graphics have been made to be used as a calculation tool. The typical structural elements of buildings subjected to bending and shear stress have been tested and analysed. The results for steel fibre-reinforced concrete (SFRC) and polyolefin fibre-reinforced concrete (PFRC) show that fibre can substitute, to some extent, part of the longitudinal reinforcement needed to provide the required flexural strength. Additionally, the fibres can reduce or even eliminate the need for stirrups for shear strength, which leads to savings in cost and execution time. [ABSTRACT FROM AUTHOR]

Cohesive granular materials are found in many natural and industrial environments, but experimental platforms for exploring the innate mechanical properties of these materials are often limited by the difficulty of adjusting cohesion strength. Granular particles levitated in an acoustic cavity form a model system to address this. Such particles self-assemble into free-floating, quasi-two-dimensional raft structures which are held together by acoustic scattering forces; the strength of this attraction can be changed simply by modifying the sound field. We investigate the mechanical properties of acoustically bound granular rafts using substrate-free micro-scale shear tests. We first demonstrate deformation of rafts of spheres and the dependence of this deformation on acoustic pressure. We then apply these methods to rafts composed of anisometric sand grains and smaller spheres, in which the smaller spheres have a thin layer of air separating them from other grain surfaces. These spheres act as soft, effectively frictionless particles that populate the interstices between the larger grains, which enables us to investigate the effect of lubricating the mixture in the presence of large-grain cohesion. [ABSTRACT FROM AUTHOR]

This paper showcases shear testing conducted on seven reinforced concrete deep beams featuring square openings, aimed at demonstrating the efficacy of a shear strengthening approach utilizing textile-reinforced concrete (TRC). This experimental program researches two types of openings of 150 × 150 mm and 200 × 200 mm at the centre of the shear spans. The solid beam undergoes testing for comparison with both the unstrengthened and strengthened beams containing openings. The study evaluates the effectiveness of TRC through a comparison of load-displacement curves, cracking patterns, and strains in reinforcements between the strengthened and un-strengthened beams. The experimental results indicate that the TRC strengthening technique effectively boosts the shear-carrying capacity of beams. Examination of the tested beams reveals a significant enhancement in stiffness at the point of maximum force, with improvements ranging from 22% to 86%, depending on the opening size and the number of reinforced textile layers. Rupture in TRC and crushing in the concrete strut are observed in the strengthened beams, whereas the un-strengthened beams show severe crushing in concrete at failure. The test results are compared with calculations based on code provisions, revealing that the prediction model consistently yields values 11 to 44% higher than the experimental results. [ABSTRACT FROM AUTHOR]