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超高层转换层钢桁架施工关键技术
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作者 吴胜辉 李永轩 +5 位作者 刘军 傅志华 吴承杰 夏子川 关雨晨 章玉容 《钢结构(中英文)》 2024年第9期52-59,共8页
杭州西站项目超高层建筑转换层采用钢桁架型钢混凝土结构,其钢桁架施工质量对结构长期性能至关重要。为保障钢桁架施工精确控制,从三个方面开展钢桁架施工关键技术研究。首先,以钢结构分段重量、吊臂、吊重等为基本参数,通过分析吊重选... 杭州西站项目超高层建筑转换层采用钢桁架型钢混凝土结构,其钢桁架施工质量对结构长期性能至关重要。为保障钢桁架施工精确控制,从三个方面开展钢桁架施工关键技术研究。首先,以钢结构分段重量、吊臂、吊重等为基本参数,通过分析吊重选择合适塔吊型号;理论分析堆载校核地下室顶板承载能力;基于四边简支双向板荷载分布影响,分析行车路线中地下室顶板最不利状态下承载能力,进而明确场地荷载部署,确保钢结构吊运能力满足要求。其次,通过建立钢结构三维模型将复杂结构可视化,检查封闭舱室判断浇筑施工难度。原方案中桁架层柱截面因多道腹板、横隔板交错形成了两层封闭舱室,且设计采用先封闭舱室注浆、后其他型钢混凝土结构统一浇筑的二次浇筑施工方法。基于深化的三维模型,以提高浇筑质量为原则,提出了钢柱横隔板顶面开设浇筑孔、内层舱室腹板开设流通孔,外层舱室不封闭而改为缀板连接,从而大大减小封闭空间;同时,基于扩大的横隔板孔洞,提出了改变混凝土流向的浇筑方案,以从上而下的一次性浇筑替代原有的先封闭压浆后支模浇筑的二次浇筑方案,优化钢结构构造保证浇筑成型。最后,结合塔吊吊装能力,设计桁架层施工安装流程。基于桁架安装流程,分析影响跨中变形影响因素;针对流程中关键参数跨中预拱度进行分析计算。胎架初始预设高度应由3部分位移组成,分别为有胎架支撑条件时半片桁架自重引起的跨中下挠、焊接完成拆除胎架后整体桁架因自重引起的跨中下挠和结构设计中考虑钢筋混凝土时设置的跨中预拱。采用ABAQUS建立三维实体非线性有限元模型,分别针对前述关键施工流程,计算考虑支撑刚度的施工状态下16.2 m跨径桁架层结构受力变形。结果显示:架设半侧桁架时,结构跨中挠度最大为6.41 mm;当拆除胎架后,结构跨中进一步下挠1.53 mm。为此,基于有限元计算结果,明确预拱值取值24.1 mm,约为跨径的1.5/1000。 展开更多
关键词 超高层 转换层 钢桁架 吊运 钢结构安装 数值模拟
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Global burden of enteric infections related foodborne diseases,1990-2021:findings from the Global Burden of Disease Study 2021
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作者 Tianyun li Ne Qiang +7 位作者 Yujia Bao yongxuan li Shi Zhao Ka Chun Chong Xiaobei Deng Xiaoxi Zhang Jinjun Ran Lefei Han 《Science in One Health》 2023年第1期189-197,共9页
Background Understanding the global burden of enteric infections is crucial for prioritizing control strategies for foodborne and waterborne diseases.This study aimed to assess the global burden of enteric infections ... Background Understanding the global burden of enteric infections is crucial for prioritizing control strategies for foodborne and waterborne diseases.This study aimed to assess the global burden of enteric infections in 2021 and identify risk factors from One Health aspects.Methods Leveraging the Global Burden of Disease(GBD)2021 database,the incidence,disability-adjusted life years(DALYs),and deaths of enteric infections and the subtypes were estimated,including diarrheal diseases,typhoid and paratyphoid fever,invasive non-typhoidal Salmonella(iNTS)infections,and other intestinal infectious diseases.The estimates were quantified by absolute number,age-standardized incidence rate(ASIR),age-standardized mortality rate(ASMR)and age-standardized DALY rate with 95%uncertainty intervals(UIs).Thirteen pathogens and three risk factors associated with diarrheal diseases were analyzed.Results In 2021,the global age-standardized DALY rate of enteric infections was 1020.15 per 100,000 popultion(95%UI:822.70-1259.39 per 100,000 population)with an estimated annual percentage change(EAPC)of-4.11%(95%confidence interval:-4.31%to-3.90%)in 1990-2021.A larger burden was observed in regions with lower socio-demographic index(SDI)levels.Diarrheal disease was the most serious subtype with Western Sub-Saharan Africa exhibiting the highest age-standardized DALY rate(2769.81 per 100,000 population,95%UI:1976.80-3674.41 per 100,000 population).Children under 5 and adults over 65 years suffered more from diarrheal diseases with the former experiencing the highest global age-standardized DALY rate(9382.46 per 100,000 population,95%UI:6771.76-13,075.12 per 100,000 population).Rotavirus remained the leading cause of diarrheal diseases despite a cross-year decline in the observed age-standardized DALY rate.Unsafe water,sanitation,and handwashing contributed most to the disease burden.Conclusion The reduced burden of enteric infections suggested the effectiveness of previous control strategies;however,more efforts should be made in vulnerable regions and populations through a One Health approach. 展开更多
关键词 Enteric infections Diarrheal disease Foodborne Disease burden Global health One Health
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