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2. Shear strength and structural behaviours of HPRWO with web openings with circular steel tubes

Author

J M Park and S J Lee

Subjects
Ultimate load, Engineering, business.industry, Shear strength, Rigidity (psychology), Fiber, Structural engineering, Composite material, Ductility, business, Failure mode and effects analysis, Sectional area
Abstract

The purpose of this study was to evaluate the shear strength and structural behavior of reinforced-concrete beams with web openings (hereinafter, "HPRWO"), where the web openings are reinforced with circular steel tubes. The experiments were conducted under the monotonic loading condition. Based on the structural experiments involving HPRWO, ultimate load ratio (d0,d0/h, etc.), ductility, load-deflection curve, and failure mode comparisons were made for evaluation purposes. This study utilized the design formula for predicting the shear strength proposed by the previous studies and formulas to determine the appropriate shear strength for HPRWO. The results of the experiments confirmed that the rigidity, ductility, and other properties of the HPRWO specimens reinforced with circular steel tubes, fiber, and admixtures were superior to those of the unreinforced HPRWOs. With Mansur's formula, a noticeable tendency for the increase in d0 and the sectional area of the web openings to lead to the overestimation of Vu/Vu,cal was found. The Vu/Vu,cal value was found to be more in line with the experiment results based on the AIJ formula compared with the results obtained using other formulas

Published
2015
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4. Beam-ion confinement for different injection geometries.

Author

W W Heidbrink, M Murakami, J M Park, C C Petty, M A Van, J H Yu, and G R McKee

Subjects
NEUTRAL beams, MAGNETIC fields, PLASMA gases, NEUTRON measurement, WAVELENGTHS, TURBULENCE, NUCLEAR counters, PLASMA confinement
Abstract

The DIII-D tokamak is equipped with neutral beam sources that inject in four different directions; in addition, the plasma can be moved up or down to compare off-axis with on-axis injection. Fast-ion data for eight different conditions have been obtained: co/counter, near-tangential/near-perpendicular and on-axis/off-axis. Neutron measurements during short beam pulses assess prompt and delayed losses under low-power conditions. As expected, co-injection has fewer losses than counter, tangential fewer than perpendicular and on-axis fewer than off-axis; the differences are greater at low current than at higher current. The helicity of the magnetic field has a weak effect on the overall confinement. Fast-ion Da (FIDA) and neutron measurements diagnose the confinement at higher power. The basic trends are the same as in low-power plasmas but, even in plasmas without long wavelength Alfven modes or other MHD, discrepancies with theory are observed, especially in higher temperature plasmas. At modest temperature, two-dimensional images of the FIDA light are in good agreement with the simulations for both on-axis and off-axis injection. Discrepancies with theory are more pronounced at low fast-ion energy and at high plasma temperature, suggesting that fast-ion transport by microturbulence is responsible for the anomalies. [ABSTRACT FROM AUTHOR]

Published
2009
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