11,701 research outputs found

    Shear behaviour of inorganic polymer concrete beams reinforced with basalt FRP bars and stirrups

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    Inorganic polymer concrete (IPC) reinforced with basalt fibre reinforced polymer (BFRP) was proposed as a promising substitute of conventional reinforced concrete for structures to enhance their sustainability and durability. This paper, for the first time, presents a systematic study, experimental, theoretical and numerical, of shear behaviour of IPC beams reinforced with BFRP bars and stirrups considering the effects of stirrup spacing (S = 80, 100 and 150 mm) and shear span-to-depth ratio (λ = 1.5, 2.0 and 2.5). Result indicates that all BFRP-IPC beams fail in shear as a result of BFRP stirrup rupture and shear-compression failure. Compared to S, λ has a more pronounced influence on shear performance of BFRP reinforced IPC beams, with a maximum reduction of ultimate shear load by 29.4%. The simulation results show good agreement with experimental data, while the theoretical predictions according to existing design provisions for FRP reinforced concrete have a discrepancy of more than 30% with experiments due to lack of consideration of λ. Modified equations taking into account the effect of λ were then derived and used to predict the shear capacity of BFRP reinforced IPC beams, which agrees well with experimental data with an average discrepancy of only around 5%

    Effect of visual landscape factors on soundscape evaluation in old residential areas

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    The visual landscape influences the soundscape experience of urban public spaces. The purpose of this study is to analyze the relationships among visual landscape factors and soundscape evaluation of old residential areas and determine their main influencing factors. In Tianjin, China, six typical old residential areas were selected to collect sound and video information. Virtual reality (VR) was used to create an evaluation environment, and subjective evaluations of the visual landscape and soundscape were accessed through questionnaire (N = 256). The results show that the evaluation of soundscape and visual landscape satisfaction of the central square in the old residential area is superior to that of the public space along the street, as affected by spatial location, sound characteristics and other factors. Greenery satisfaction, environmental cleanliness, and architectural aesthetics were significantly positively correlated with soundscape evaluation. Additionally, three latent variables, namely, visual landscape factors, spatial factors and soundscape evaluation factors, were identified through factor analysis, and a structural equation model (SEM) of “visual landscape factors–soundscape evaluation” was built. The visual landscape factors in old residential areas were found to be important factors affecting soundscape evaluation. The standardization coefficient was 0.46 (P ≀ 0.01). Although the spatial factors have no direct contribution to the soundscape evaluation of the old residential areas, its observation variable, environmental cleanliness, is significantly positively correlated with all the observed variables of the soundscape evaluation factors

    An extended view of the Pisces Overdensity from the SCUSS survey

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    SCUSS is a u-band photometric survey covering about 4000 square degree of the South Galactic Cap, reaching depths of up to 23 mag. By extending around 1.5 mag deeper than SDSS single-epoch u data, SCUSS is able to probe much a larger volume of the outer halo, i.e. with SCUSS data blue horizontal branch (BHB) stars can trace the outer halo of the Milky Way as far as 100-150 kpc. Utilizing this advantage we combine SCUSS u band with SDSS DR9 gri photometric bands to identify BHB stars and explore halo substructures. We confirm the existence of the Pisces overdensity, which is a structure in the outer halo (at around 80 kpc) that was discovered using RR Lyrae stars. For the first time we are able to determine its spatial extent, finding that it appears to be part of a stream with a clear distance gradient. The stream, which is ~5 degrees wide and stretches along ~25 degrees, consists of 20-30 BHBs with a total significance of around 6sigma over the background. Assuming we have detected the entire stream and that the progenitor has fully disrupted, then the number of BHBs suggests the original system was similar to smaller classical or a larger ultra-faint dwarf galaxy. On the other hand, if the progenitor still exists, it can be hunted for by reconstructing its orbit from the distance gradient of the stream. This new picture of the Pisces overdensity sheds new light on the origin of this intriguing system.Comment: 8 pages, 4 figures, accepted by Ap
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