• Structural Engineering and Mechanics
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• v.84 no.3
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• pp.311-321
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• 2022

In the buildings with long spans and high floors, such as logistics warehouses and semiconductor factories, it is difficult to install supporting posts under beams during construction. Therefore, the size of structural members becomes larger inevitably, resulting in a significant increase in construction costs. Accordingly, a prestressed hybrid wide flange (PHWF) beam with hollowed steel webs was developed, which can reduce construction costs by making multiple openings in the web of the steel member embedded in concrete. However, since multiple openings exist and prestress is introduced only into the bottom flange concrete, it is necessary to identify the shear resistance mechanism of the PHWF beam. This study presents experimental shear tests of PHWF beams with hollowed steel webs. Four PHWF beams with cast-in-place (CIP) concrete were fabricated, with key variables being the width and spacing of the steel webs embedded in the concrete and the presence of shear reinforcing bars, and web-shear tests were conducted. The shear behavior of the PHWF beam, including crack patterns, strain behavior of steel webs, and composite action between the prestressed bottom flange and CIP concrete, were measured and analyzed comprehensively. The test results showed that the steel web resists external shear forces through shear deformation when its width is sufficiently large, but as its width decreased, it exerted its shear contribution through normal deformation in a manner similar to that of shear reinforcing bars. In addition, it was found that stirrups placed on the cross section where the steel web does not exist contribute to improving the shear strength and deformation capacity of the member. Based on the shear behavior of the specimens, a straightforward calculation method was proposed to estimate the web-shear strength of PHWF beams with CIP concrete, and it provided a good estimation of the shear strength of PHWF beams, more accurate than the existing code equations.

• The Journal of the Korea Contents Association
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• v.17 no.2
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• pp.623-636
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• 2017

The use of virtual reality(VR)-based interventions for students with autism spectrum disorders(ASD) has received special attention as evidence-based practices for its feasiblity, practicality, and appropriateness. However, there is little research to investigate the effects of VR-based intervention for students with ASD in Korea. This study identifies and reviews studies applying VR-based interventions. In total, 13 experimental studies were found that examine the effects of VR interventions published from 1990 to 2016. The selected studies were analyzed by 6 variables including publication year, participants, research design, independent variable, dependent variable, and outcome. The results of this study showed the feasibility of the implementing VR-based interventions in various age group students with ASD. In addition, the utilization of VR techniques was particularly effective in improving a wide range of social communication skills including facial recognition, empathy, joint attention, understanding social context, and resolving issues due to limited cognitive abilities. Several recommendations for the future study on VR-based intervention for students with ASD such as interdisciplinary approach to VR-based interventions, support needs regarding characteristics of ASD, generalization and maintenance of acquired technology, and consideration for participants' cultural background. were discussed.