保证混凝土施工质量的注意事项

本文主要论述了施工中如何保证混凝土的质量及相应的注意事项。     

影响钢筋混凝土桥梁耐久性的原因

在分析影响钢筋混凝土桥梁耐久性原因的基础上,介绍提高混凝土桥梁耐久性的新方法,以期引起桥梁建设者对桥梁耐久性的重视。     

我国大跨空间钢结构应用发展的主要特点

根据我国网架、网壳、管桁结构等大跨空间钢结构获得广泛应用的实际情况,将其归结为结构形式多样化、结构新材料应用的拓展及现代预应力技术的引入;并阐明推动大跨空间钢结构发展的源动力是产、学、研的紧密结合,是一系列空间结构行业标准的制定及企业资质论证与建筑管理的加强。     

Analysis on Mechanical Behavior of Welding-Overlap Splices for Mid-Diameter Steel Bars

An improved splice method for mid-diameter steel bars (10-16mm) used in RC structures was developed, which can make the installation more easily and economic through the hybrid connection of welding and overlapping. In order to study the mechanical behavior of welding-overlap splices, a total of 138 steel bar splice tests were conducted, including both the steel-concrete interaction group and the lonely-steel group. Through the splice tensile experiment, the failure model and ultimate strength of the improved splice was summarized. Meanwhile, the failure mechanism was analyzed by the FEM analysis. The test results show that: hybrid connection of welding and overlapping is a simpler splice method which can realized the reliable splice in the RC structures, the ultimate load of the improved splice is sufficient for the application and the failure model is reasonable. Base on the test results, some suggestions for application were given. The economic analysis of a real application case is conducted, which shows a good prospect of proposed connection.     

Fire Resistance Analysis of High Strength Q460 Steel Beams-Part I：Theoretical Analysis

In order to investigate the fire resistance of high strength steel beams made from Q460, the method to compute temperature distribution of high strength Q460 steel beams was derived and the temperature distribution was calculated by using finite difference method. The modified equations of temperature for components of steel beam were proposed. According to critical moment at room temperature and mechanical properties of high strength Q460 steel at elevated temperature, the critical moment and stability checking coefficient were obtained by analysis. The load bearing capacity and critical temperature as well as stability factor were studied by using equivalent stiffness method through considering the effect of temperature gradient on stiffness.     

钢管磁性探伤多传感器信息融合模型的研究

针对大型钢管裂纹与孔洞的局部损伤缺陷,采用非晶态合金多传感器阵列获取钢管在空间与时间上的多源缺陷信息.通过实验提取了反映钢管缺陷的特征信号,建立缺陷状态数学模型,形成了多传感器信息融合所需的先验知识.基于多传感器信息融合原理,构建了适合于钢管损伤的多传感器信息融合模型,研究了模型在不同层次上的信息融合特点,提高了对钢管局部损伤状态定量识别与评估的准确性和可靠性.     

PRO／E软件装配式建模在钢结构分析中的应用

通过钢框架节点案例详细阐述了PRO／E软件在钢结构分析中的建模过程。所述方法较其他结构软件原理方法简单,可明显缩短建模时间,提高建模的精度和准确性,具有一定的推广意义。     

辙叉用耐磨钢回火试验

采用对比试验的方法,从200℃开始设置6种不同温度,研究耐磨钢的焊后合理回火温度。结果表明,综合耐磨钢在微观金相组织、表面硬度、拉伸性能、冲击性能方面的变化情况,焊后回火温度以350℃为宜。     

水生植物作用下浅水湖泊中营养盐（P、Fe、Mn）的分布特征及相关性研究

通过对骆马湖进行采样分析,探讨大型水生植物生长区的水体和沉积物中磷(P)、铁(Fe)、锰(Mn)的分布特征,并对浅水湖泊沉积物-水界面中Fe、Mn和P的含量进行了相关性分析,结果表明:大型水生植物生长区的TP、Fe、Mn含量均显著低于对照;沉积物孔隙水中各营养盐浓度均较上覆水高,表层沉积物出现富集现象;沉积物中营养盐的垂直变化存在差异,磷的赋存形式以无机磷的Ca-P为主。相关性分析显示,在大型水生植物作用下,沉积物中Fe和Fe-P、TP呈显著负相关,摩尔比Fe/P和Mn/P随深度的增加而增大,表明Fe和Mn在湖泊体系的磷迁移过程中具有重要影响。     

T8工具钢淬火裂纹的焊接修复

针对T8工具钢淬火后的焊接特性,分析了T8钢导轨的使用要求,制定了一套修复焊补方案,满足了使用要求。