Browsing by Subject "Uniform load"
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Item Behavior of slender beams without stirrups: effects of load distribution and member depth(2015-12) Klein, Joseph Robert; Bayrak, Oguzhan, 1969-; Hrynyk, Trevor DThough uniform loading is common in structures, the vast majority of all shear strength tests on slender reinforced concrete members without stirrups have been performed using concentrated loading. Furthermore, the uniform load tests that have been conducted typically involve members with smaller specimen depths (d) and larger reinforcement ratios (ρ) than are commonly used in practice. Previous studies usually agree that a noticeable increase in shear strength can be expected when a specimen is subjected to uniform loading as opposed to concentrated loading. Six shear tests were performed on four slender beams without stirrups at The University of Texas at Austin. Two of the specimens had approximately double the effective depth (d) as the other two. For a given depth, two concentrated load tests were carried out on either end of one specimen, and one uniform load test was carried out on the second specimen. Thus, four reinforced concrete beams were used to perform a total of four concentrated load tests and two uniform load tests, with the objective of determining the influence of load distribution as member depth (d) increases. To ensure that a direct comparison could be made between each load distribution, the ratio between maximum bending moment and maximum shear force was maintained for all tests. Additionally, to provide consistency with typical design practice, the reinforcement ratio (ρ) was selected to match that of a typical beam. The experimental results presented an influence of load distribution opposite to that of previous studies, with a range of increase in shear strength at first diagonal cracking of concentrated load tests of -16 to 50 percent, with an average increase of 18 percent, over uniform load tests. Additionally, the tests with smaller effective depths (d) saw a percent increase in shear strength of 31 to 68 percent, with an average increase of 50 percent, over tests with larger effective depths (d).Item Effect of uniform load on the shear strength of slender beams without shear reinforcement(2014-08) Dassow, Nicholas Alan; Bayrak, Oguzhan, 1969-; Hrynyk, TrevorPrevious studies have shown that a uniform distribution of load may increase the shear strength of a slender member by as much as 40 percent (Leonhardt and Walther 1964). The increase of shear strength is potentially due to clamping stresses induced from the uniform load, although a mathematical equation to quantify the effect of clamping stress in slender uniformly loaded members has yet to be derived (Acevedo et al. 2009). Only a small percentage of all shear tests on slender specimens without shear reinforcement were completed with uniform load. Additionally, the majority of uniform load data consists of specimens with small specimen depths (d) and large longitudinal reinforcement ratios (ρ). Six shear tests on specimens without shear reinforcement were completed at the University of Texas at Austin. Three of the six specimens were subjected to concentrated load, and the remaining three companion specimens were loaded uniformly. These specimens are among the deepest slender members without shear reinforcement that have ever been tested under a uniform load distribution. Importantly, the ratio of maximum shear to maximum moment was maintained between concentrated and uniform load tests which ensures directly comparable tests results. The experimental results were shown to be influenced by load distribution. Uniformly loaded specimens had an average increase in first diagonal cracking shear capacity of 17 percent with a range of increase between 10 and 23 percent when compared with specimens subjected to concentrated loads.