STR-811: EXAMINATION OF EFFECTIVE LENGTH FACTOR FOR RC COLUMNS IN NON-SWAY FRAMES

The Canadian Standards Association (CSA) Standard for Design of Concrete Structures (A23.3-04) permits the use of moment magnifier method for computing the design ultimate strength of slender reinforced concrete (RC) columns that are part of non-sway frames. This computed strength is influenced by the column effective length factor K, effective flexural stiffness EI, and equivalent uniform bending moment diagram factor Cm among others. Previous investigations by the authors examined the equations available in literature for computing EI and Cm factor. For this study, nearly 3000 simple non-sway reinforced concrete frames subjected to short-term loads were simulated and used to investigate the effect of using different equations for the effective length factor K when computing the strength of columns in these frames by the moment magnifier approach. An elaborate theoretical model was developed and used for computing the ultimate strength of columns in simulated frames. The theoretically computed column ultimate strengths were compared to the ultimate strengths of the same columns computed from the CSA moment magnifier method using selected equations for K available in literature. For the purpose of analysis, the theoretically computed strengths were divided by the CSA strengths to obtain the so-called strength ratios. The statistical analyses of strength ratios presented in this paper show that, for computing the CSA ultimate strength of columns in non-sway frames, the current practice of using Jackson-Moreland Alignment Chart is the most accurate method for determining the effective length factor

Physical activity attenuates the influence of FTO variants on obesity risk: A meta-analysis of 218,166 adults and 19,268 children

Background: The FTO gene harbors the strongest known susceptibility locus for obesity. While many individual studies have suggested that physical activity (PA) may attenuate the effect of FTO on obesity risk, other studies have not been able to confirm this interaction. To confirm or refute unambiguously whether PA attenuates the association of FTO with obesity risk, we meta-analyzed data from 45 studies of adults (n = 218,166) and nine studies of children and adolescents (n = 19,268). Methods and Findings: All studies identified to have data on the FTO rs9939609 variant (or any proxy [r2>0.8]) and PA were invited to participate, regardless of ethnicity or age of the participants. PA was standardized by categorizing it into a dichotomous variable (physically inactive versus active) in each study. Overall, 25% of adults and 13% of children were categorized as inactive. Interaction analyses were performed within each study by including the FTO×PA interaction term in an additive model, adjusting for age and sex. Subsequently, random effects meta-analysis was used to pool the interaction terms. In adults, the minor (A-) allele of rs9939609 increased the odds of obesity by 1.23-fold/allele (95% CI 1.20-1.26), but PA attenuated this effect (pinteraction= 0.001). More specifically, the minor allele of rs9939609 increased the odds of obesity less in the physically active group (odds ratio = 1.22/allele, 95% CI 1.19-1.25) than in the inactive group (odds ratio = 1.30/allele, 95% CI 1.24-1.36). No such interaction was found in children and adolescents. Concl