253 research outputs found

    Effect of Adhesive Stiffness and CFRP Geometry on the Behavior of Externally Bonded CFRP Retrofit Measures Subject to Monotonic Loads

    Get PDF
    Nine 10" (254 mm) deep, 6" (152 mm) wide and 186" (4730 mm) long concrete beams having three #4 longitudinal steel reinforcing bars as primary flexural reinforcement, were tested monotonically to failure under mid-point bending. Eight beams were strengthened with various arrangements of soffit-mounted externally bonded carbon fiber reinforced polymer (CFRP) and one beam was left as an unretrofit control specimen. A commercially available 4" (102 mm) wide, 0.055" (1.4 mm) thick preformed unidirectional high strength carbon fiber (CFRP) strip system was used in this study. Additionally, two commercially available adhesives, with significantly different moduli, were used to apply the CFRP strips to the concrete substrate. In order to investigate the effect of the CFRP strip width-to-soffit width ratio (bf/b), four different strip arrangements were used. All specimens tested in this program exhibited intermediate crack induced debonding behavior. The observed failures were generally bond-induced although concrete crushing was also observed in all cases. Increased flexural capacity and decreased flexural ductility was observed with increasing CFRP retrofit material area. Observations indicate retrofit geometry has an influence on the overall retrofit performance. The FRP width-to-substrate width ratio (bf/b) is shown to affect intermediate crack induced debonding behavior - an increase in strain at debonding is seen for specimens having a smaller bf/b ratio. Additionally, superior performance in the form of higher general yield and maximum loads, and higher deflections at these loads, was observed for the specimens having the lower modulus of elasticity adhesive. The current American Concrete Institute (ACI) recommendation intended to mitigate debonding failure by limiting the allowable strain in the FRP (the limiting strain is referred to as Ă„fub) is shown to be non-conservative, overestimating the strain where debonding becomes likely by two fold for the high modulus adhesive and less so for the low modulus adhesive. The equation for estimating Ă„fub recommended by Teng et al. (2001), including the modifying kb term, appears to provide appropriately conservative estimates of debonding for the specimens having low modulus adhesive although remains unconservative for the high modulus adhesive. This indicates that the nature of the adhesive should be included in the calculation of limiting strain. Proposed values for the coefficient kb which accounts for the bf/b ratio were found to generally underestimate the effect of the width ratio for the test specimens. Therefore, not only is the ratio bf/b (as represented by kb) a contributing factor to bond behavior, its contribution may be underestimated. Cover delamination (end peel debonding) was effectively mitigated in all specimens by extending the CFRP close to the support along the relatively long shear span

    Valuation of Child Behavioral Problems from the Perspective of US Adults

    Get PDF
    To assess preferences between child behavioral problems and estimate their value on a quality-adjusted life year (QALYs) scale

    Using collaborative hackathons to coproduce knowledge on local climate adaptation governance

    Get PDF
    While coproduction of knowledge is growing in popularity in social sciences, and especially climate change research, we still need to better understand how to coproduce climate knowledge. In this paper, we explore how collaborative climate hackathons coproduce local adaptation knowledge, and what this method reveals about local climate governance. The data derives from two collaborative climate hackathons, called Klimathons, that attracted 73 and 98 participants in Bergen, Norway. The participants were practitioners and decision-makers from local, regional, and national institutions as well as researchers from natural and social climate sciences. The collaborative group work revolved around the challenges and solutions of local adaptation planning and uncovered how a diversity of key actors understand the local adaptation work in Norway. These interventions revealed that there are significant disagreements and divergent understanding of relevant laws, regulations and responsibility between practitioners working within the same governance system. Though the cross-sectorial interaction does not dissolve these divergences, they allow actors to renegotiate boundaries between divergent knowledge communities. The Klimathons helped us navigate the complexity of local climate adaptation by shifting the focus to how different actors make sense of and work on adaptation and showing the intertwining and interdependence of potential drivers for adaptation.publishedVersio

    The Value Adults Place On Child Health And Functional Status

    Get PDF
    By summarizing the value adults place on child health and functional status, this study provides a new quantitative tool that enhances our understanding of the benefits of new health technologies and illustrates the potential contributions of existing datasets for comparative effectiveness research in pediatrics

    Exercising control at the urban scale: Towards a theory of spatial organisation and surveillance

    Get PDF
    The purpose of this chapter is to explore how urban spaces are implicated in the control and surveillance of users in a culture saturated by the notion of the self as a consuming body or entity. Using the work of Foucault on disciplinary cultures, Lefebvre in relation to the production of space, and other seminal theorists such as Baudrillard, Bauman, Shields, and Walzer, a model for analysing the three dimensions of social spatialisation is proposed and illustrated by reference to contemporary public spaces, and specifically spaces of mundane leisure such as shopping malls and high streets. The chapter deals with how the public realm as a controlling space has been theorised in terms of opposition to such controlling tendencies—from the flaneur, through the self-constructed narratives of De Certeau’s walker to the digitally ‘enhanced’ individual today, appropriating space via technology and their own projects in tinder and so on, and other potentially subversive media

    Few smooth d-polytopes with n lattice points

    Get PDF
    We prove that, for fixed n there exist only finitely many embeddings of Q-factorial toric varieties X into P^n that are induced by a complete linear system. The proof is based on a combinatorial result that for fixed nonnegative integers d and n, there are only finitely many smooth d-polytopes with n lattice points. We also enumerate all smooth 3-polytopes with at most 12 lattice points. In fact, it is sufficient to bound the singularities and the number of lattice points on edges to prove finiteness.Comment: 20+2 pages; major revision: new author, new structure, new result

    Assessing health and well-being among older people in rural South Africa

    Get PDF
    Background: The population in developing countries is ageing, which is likely to increase the burden of noncommunicable diseases and disability. Objective: To describe factors associated with self-reported health, disability and quality of life (QoL) of older people in the rural northeast of South Africa. Design: Cross-sectional survey of 6,206 individuals aged 50 and over. We used multivariate analysis to examine relationships between demographic variables and measures of self-reported health (Health Status), functional ability (WHODASi) and quality of life (WHOQoL). Results: About 4,085 of 6,206 people eligible (65.8%) completed the interview. Women (Odds Ratio (OR) 1.30, 95% CI 1.09, 1.55), older age (OR2.59, 95% CI 1.97, 3.40), lower education (OR1.62, 95% CI 1.31,2.00), single status (OR1.18, 95% CI 1.01, 1.37) and not working at present (OR1.29, 95% CI 1.06, 1.59) were associated with a low health status. Women were also more likely to report a higher level of disability (OR1.38, 95% CI 1.14, 1.66), as were older people (OR2.92, 95% CI 2.25, 3.78), those with no education (OR1.57, 95% CI 1.26, 1.97), with single status (OR1.25, 95% CI 1.06, 1.46) and not working at present (OR1.33, 95% CI 1.06, 1.66). Older age (OR1.35, 95% CI 1.06, 1.74), no education (OR1.39, 95% CI 1.11, 1.73), single status (OR1.28, 95% CI 1.10, 1.49), a low household asset score (OR1.52, 95% CI 1.19, 1.94) and not working at present (OR1.32; 95% CI 1.07, 1.64) were all associated with lower quality of life. Conclusions: This study presents the first population-based data from South Africa on health status, functional ability and quality of life among older people. Health and social services will need to be restructured to provide effective care for older people living in rural South Africa with impaired functionality and other health problems
    • 

    corecore