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Numerical Study on Performance of Prefabricated RCS Joint under Normal Temperature and Fire
Qi Si,Zhihong Pan 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11
To study the mechanical behavior and fire resistance of the prefabricated reinforced concrete column and steel beam (RCS) joints with endplate, this paper presented a numerical investigation on the joints under normal temperature and fire. The full 3D solid finite element models were implemented in ABAQUS. The simulated results show that under normal temperature, the yield moment and initial rotation stiffness increase with the increase of the endplate thickness, the failure mode changes from deformation of the endplate to yield of the extensional part. Increasing the thickness of stiffeners and changing the form of stiffeners can effectively improve the yield moment of the joint, but the initial rotational stiffness keeps invariant basically. Under fire condition, the load ratio has a significant effect on the fire resistance of the prefabricated RCS joint; the thickness of the endplate and stiffener, the stiffener form have less influence on the fire resistance of the joint.
Mu Danni,Fang Jiadan,Yu Songlin,Ma Yichen,Cheng Jin,Hu Yingying,Song Ailing,Zhao Fang,Zhang Qi,Qi Zhihong,Zhang Kui,Xia Liangyu,Qiu Ling,Zhu Huijuan,Cheng Xinqi 대한진단검사의학회 2024 Annals of Laboratory Medicine Vol.44 No.1
Background: Twenty-four-hour urinary free cortisol (UFC) measurement is the initial diagnostic test for Cushing’s syndrome (CS). We compared UFC determination by both direct and extraction immunoassays using Abbott Architect, Siemens Atellica Solution, and Beckman DxI800 with liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, we evaluated the value of 24-hr UFC measured by six methods for diagnosing CS. Methods: Residual 24-hr urine samples of 94 CS and 246 non-CS patients were collected. A laboratory-developed LC-MS/MS method was used as reference. UFC was measured by direct assays (D) using Abbott, Siemens, and Beckman platforms and by extraction assays (E) using Siemens and Beckman platforms. Method was compared using Passing–Bablok regression and Bland–Altman plot analyses. Cut-off values for the six assays and corresponding sensitivities and specificities were calculated by ROC analysis. Results: Abbott-D, Beckman-E, Siemens-E, and Siemens-D showed strong correlations with LC-MS/MS (Spearman coefficient r=0.965, 0.922, 0.922, and 0.897, respectively), while Beckman-D showed weaker correlation (r=0.755). All immunoassays showed proportionally positive bias. The areas under the curve were 0.975 for Abbott-D, 0.972 for LC-MS/MS, 0.966 for Siemens-E, 0.948 for Siemens-D, 0.955 for Beckman-E, and 0.877 for Beckman-D. The cut-off values varied significantly (154.8–1,321.5 nmol/24 hrs). Assay sensitivity and specificity ranged from 76.1% to 93.2% and from 93.0% to 97.1%, respectively. Conclusions: Commercially available immunoassays for measuring UFC show different levels of analytical consistency compared to LC-MS/MS. Abbott-D, Siemens-E, and Beckman-E have high diagnostic accuracy for CS.