Concrete-filled elliptical section steel columns under concentric and eccentric loading

A comprehensive programme of testing of concrete-filled elliptical section steel tubular columns of varying slenderness has been undertaken at Imperial College London. A total of 27 specimens were prepared of varying lengths, including three stub columns, with seven of the tested specimens also possessing steel reinforcement. The specimens were then loaded in compression, either concentrically or with different major axis or minor axis eccentricities. Load, end-shortening, midheight strains, lateral deflection at mid-height and end rotations were measured. These results were then used to validate a finite element model developed in ABAQUS, which incorporated steel material stress–strain properties from tensile testing and a confined concrete model using the measured concrete strengths. The numerical results are shown to agree well with those obtained from the experiments when comparing ultimate load, load–deflection behaviour and failure modes. This allowed a parametric study to be undertaken where the slenderness and load eccentricity of the concrete-filled columns were varied, creating a data set to be used as the basis for developing simplified design rules for inclusion in codes such as Eurocode 4.</p

Numerical study of concrete-filled steel elliptical hollow section beam-columns

A nonlinear finite element (FE) study of concrete-filled steel elliptical hollow section (EHS) beam-columns is presented in this paper. First, a summary of experiments conducted on a total of 27 EHS specimens with varying lengths and different load eccentricities, with seven of the tested specimens containing steel reinforcement, is presented. These results, together with other results from the literature, were used to validate a nonlinear finite element model developed in ABAQUS, which incorporated steel material properties obtained from tensile testing and a confined concrete model calibrated with measured concrete strengths. The numerical results were found to agree well with those obtained from the experiments when comparing ultimate loads, load–deflection behaviour and failure modes. Upon validation of the models, an extensive parametric study comprising 240 simulations was conducted to investigate the effects of cross-section slenderness, nondimensional member slenderness, loading eccentricities and embedded reinforcement. Both the experimental and numerical results have been used as the basis for developing simplified design rules for inclusion in codes such as EN 1994-1-1.</p

Additional file 1 of Chronic diseases and determinants of community health services utilization among adult residents in southern China: a community-based cross-sectional study

Supplementary Material

The intersession reproducibility of Ks, Kf, Km, J0 and J45 obtained by iTrace.

<p>(Note: D: diopter, SD: standard deviation, Sw: within-subject standard deviation, CoV: within-subject coefficient of variation, ICC: intraclass correlation coefficient.)</p

Band-Altman plots present the mean plotted against the differences in values of Ks for a comparison between the Topcon KR-1W and Topolyzer (A), Topcon KR-1W and IOLMaster (B), iTrace and Topolyzer (C), iTrace and IOLMaster (D), Topcon KR-1W and iTrace (E), Topolyzer and IOLMaster (F).

<p>The solid line indicates the mean difference. The interval between upper and lower lines represent the 95% LoA.</p

The interobserver reproducibility of Ks, Kf, Km, J0 and J45 obtained by Topcon KR-1W.

(Note: D: diopter, SD: standard deviation, Sw: within-subject standard deviation, CoV: within-subject coefficient of variation, ICC: intraclass correlation coefficient.)</p

Precision (repeatability and reproducibility) of ocular parameters obtained by the Tomey OA-2000 biometer compared to the IOLMaster in healthy eyes

<div><p>Purpose</p><p>To assess the precision (repeatability and reproducibility) of ocular parameters measured by the Tomey OA-2000 biometer, and to compare them with those measured by the IOLMaster.</p><p>Methods</p><p>In this prospective study, the right eyes of 108 healthy subjects were included. Three consecutive scans were obtained by 2 observers using the Tomey OA-2000, and in the same session one observer used the IOLMaster (version 5.4.4.0006) for the measurements. About 1 week later, 3 scans were obtained by one observer using the Tomey OA-2000. The axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), keratometer readings, pupil diameter (PD) and corneal diameter (CD) values measured by the Tomey OA-2000 and IOLMaster were analyzed. The coefficient of variation (CoV), intraclass correlation coefficient (ICC), within subject standard deviation (Sw) and 2.77Sw were calculated to assess the repeatability and reproducibility. The paired t test and Bland-Altman plots were used to analyze the differences and agreements of parameters measured by the two devices, respectively.</p><p>Results</p><p>Intraobserver repeatability, and interobserver and intersession reproducibility of the AL, CCT, ACD, LT, Kf, Ks, Km, PD and CD values measured by the Tomey OA-2000 biometer showed a CoV of less than 1% except that for PD, and an ICC of more than 0.97 except that for PD and CD. The AL, Kf, Ks, Km and CD values measured by the Tomey OA-2000 were 0.058 ± 0.094 mm, 0.088± 0.150 diopters (D), 0.163 ± 0.170 D, 0.127 ± 0.117 D and 0.171 ± 0.217 mm lower than those measured by the IOLMaster, respectively (all <i>Ps</i> < 0.05). However, the ACD values from the two devices were comparable (P = 0.169). The 95% linite of agreement (LoA) of the AL, ACD, CD and all keratometer readings were no more than 0.24 mm, 0.14 mm 0.60 mm and 0.5 D, respectively.</p><p>Conclusion</p><p>Except for the PD and CD, the ocular parameters measured by the Tomey OA-2000 were highly repeatable and reproducible. Except for the CD value, there was good agreement of ocular parameters measured by the Tomey OA-2000 and the IOLMaster in healthy eyes.</p></div

Comparison of Ks, Kf and Km obtained by Topcon KR-1W and IOLMaster.

(Note: Ks: steep keratometry, Kf: flat keratometry, Km: mean keratometry, D: diopter, SD: standard Error, 95% CI: 95% consistent interval, * Bonferroni corrected.)</p

Band-Altman plots present the mean plotted against the differences in values of Kf for a comparison between the Topcon KR-1W and Topolyzer (A), Topcon KR-1W and IOLMaster (B), iTrace and Topolyzer (C), iTrace and IOLMaster (D), Topcon KR-1W and iTrace (E), Topolyzer and IOLMaster (F).

<p>The solid line indicates the mean difference. The interval between upper and lower lines represent the 95% LoA.</p

Comparison of ocular parameters measured by Tomey OA-2000 biometer and IOLMaster (n = 108).

<p>Comparison of ocular parameters measured by Tomey OA-2000 biometer and IOLMaster (n = 108).</p