市政桥梁钢箱梁梁段安装方法研究

大型市政钢箱梁桥梁具有跨度大、质量大的特点,在施工过程中需要将箱梁划分为若干个梁段,以便运输、吊装、组对以及焊接。研究过程旨在探索此类工程的施工方法,以国内某跨河桥梁为分析对象,重点探讨了钢箱梁节段划分方法、临时支撑体系的设计方法与力学验算、钢箱梁分段吊装、合龙测量、合龙过程控制、钢梁焊接工艺和焊接顺序等内容,形成了较为全面的梁段安装施工工艺。     

太原高铁站钢箱梁吊装关键技术

本文以太原火车站高架桥梁工程为例,探讨了钢箱梁施工中的吊装技术,总结了吊装方案与吊装技术在施工中的应用,针对高铁站高架桥梁施工的复杂性,提出了可适用的钢箱梁吊装方案,并在吊装过程中对钢箱梁进行检测,提高了钢箱梁施工安全、质量,保证了高架桥梁工程钢箱梁结构的稳定性.     

大型变截面预应力钢箱梁施工技术分析

大型变截面预应力钢箱梁由于其承载能力强、抗弯刚度大,因此在城市建设中受到了越来越多的青睐,广泛应用在城市立交桥、港口码头中。本文以某市立交桥工程为例,分析了变截面钢箱梁结构的优点和施工的难点,且对钢箱梁施工中存在的问题进行了分析,如大型钢箱梁由于结构尺寸大而导致的焊接问题、吊装的问题等,论述了影响焊接变形的因素,提出了钢箱梁的焊接质量检验方法及改进措施,最后论述了钢箱梁运输和安装需要注意的问题。     

空间受限跨运营公路钢箱梁吊装技术

为解决中心城区空间受限条件下跨线钢箱梁的吊装问题，本文以北京市丰台区正丰草河路跨三环节点桥钢箱梁吊装为例，分析施工的重难点，研究钢箱梁的吊装施工技术以及施工变形控制技术。结果表明：正丰草河北路跨三环节点桥跨越了运营中的西三环，因此采用400t（履带吊）和350t（汽车吊）进行构件卸车及吊装就位，实测挠度值与计算值相比，呈现出不同程度的波动，且最大挠度值与计算值相比略大。     

城市主干道高架立交钢箱梁安装技术介绍

本文结合城市主干道立交工程,介绍了一种钢箱梁安装的施工工艺、技术难点、运输、吊装、焊接、螺栓施拧和安装等技术措施,可供相关技术人员参考.     

泰州大桥悬索主桥钢箱梁吊装施工顺序的确定

泰州大桥是世界上首座超千米的三塔两跨悬索桥,主跨为2×1 080 m,中塔采用纵向"人"字形、横向门式框架型钢塔,边塔采用门式框架型混凝土塔,加劲梁为扁平流线型钢箱梁结构,全桥共136片钢箱梁,总重约33 426 t。通过分析钢箱梁吊装顺序对结构体系和施工难度的影响,确定了三塔悬索桥合适的钢箱梁吊装顺序。     

大跨度三跨连续悬索桥钢箱梁总体吊装方案研究

三跨连续悬索桥不同于单跨悬索桥,两边跨设置吊杆,在主塔区域设置无吊索梁段实现中边跨加劲梁之间的连续过渡,并且一般在边跨过渡墩处设置限位转置,实现该区域主缆和加劲梁的协调变形,是其主要结构特点;因此该类型悬索桥加劲梁的吊装方法及关键施工工序也相对较为复杂。以南京长江第四大桥为工程背景,针对大跨度三跨连续悬索桥的结构特点,通过对两种不同的钢箱梁吊装顺序进行比选分析,确定合理的钢箱梁吊装方案。     

大体积混凝土施工技术浅析

本文通过作者工程实际经验以某工程为实例介绍了钢箱梁的加工、安装以及吊装运输方案，对实际施工过程中的部分值得注意的问题予以总结归纳。     

钢箱梁吊装施工技术及质量控制

以东江梨川大桥跨东莞水道独塔无背索竖琴式钢砼混合梁斜拉桥为例,阐述了钢箱梁吊装施工工艺,提出钢箱梁吊装施工质量的管理和控制。     

钢箱梁架设施工技术分析

某项目难点施工为架设3片钢箱梁（垂直于桥向），每片由5节（沿桥向）钢箱粱组成，其约600吨。采用先轮箱纵移到钢箱梁对应的跨位，再利用自锁爬行顶推小车横移至梁位处，落梁就位（中间9节钢箱梁）。两头的钢箱梁利用大吨位吊车和已经就位好的钢箱梁对接架设。很好地解决了单片整体吊装钢箱梁接头变形影响问题。     

Gender differences in publication productivity in psychology in India

An analysis of gender differences in psychology in India provides quantitative and qualitative assessment of R&D output contributed by psychologists with the indication of the trend of growth, skewness, relatedness, co-authorship pattern of productivity.     

Metrology in Chemistry in Germany

The system for Metrology in Chemistry in Germany is described. At the national standards level, a network of high-level chemistry institutes coordinated by the national metrology institute, PTB, provides the primary references for chemical measurements. A dissemination mechanism employs chemical calibration laboratories accredited within the framework of the German Calibration Service (DKD). They act as “multipliers” between the national standards level and the user level by providing the user with calibration means which are traceable to the SI via national standards. Traceability structures in clinical chemistry, electrochemistry, elemental analysis and gas analysis are described     

Natural radioactivity in drinking water in private wells in Finland

Natural radioactivity in drinking water was determined in population-based random study of 472 private wells. The mean concentrations of (222)Rn, (226)Ra, (234)U, (238)U, (210)Pb and (210)Po in drilled wells were 460, 0.05, 0.35, 0.26, 0.04 and 0.05 Bq l(-1), and in wells dug in the soil were 50, 0.016, 0.02, 0.015, 0.013 and 0.007 Bq l(-1), respectively. Approximately 10% of the drilled wells exceeded a radon concentration of 1000 Bq l(-1) and 18% a uranium concentration of 15 microg l(-1). The mean annual effective dose from natural radionuclides for a drilled well user was 0.4 mSv and 0.05 mSv for a user of a well dug in the soil. The effective dose arising from (222)Rn was 75% of the total of all natural radionuclides for drilled well users. As regards long-lived radionuclides, (210)Po and (210)Pb caused the largest portion of the effective dose. The dose arising from (238)U, (234)U and (226)Ra was only 8% of the total of all natural radionuclides.     

Natural radioactivity in drinking water in private wells in Finland

Radiation Protection Dosimetry     

Radioactivity in building materials in Iraq

Activity concentrations of (226)Ra, (232)Th and (40)K in 45 samples of different building materials used in Iraq were measured using gamma-spectroscopy system based on high-purity germanium detector with an efficiency of 40 %. Radium equivalent activity, air-absorbed dose rate, annual effective dose, external and internal hazard indices and alpha index due to radon inhalation originating from building materials were measured to assess the potential radiological hazard associated with these building materials. The activity concentrations of the natural radionuclides (226)Ra, (232)Th and 40K were found to range from below detection limit (BDL) to 223.7 ± 9, BDL to 93.0 ± 3 and BDL to 343.1 ± 12, respectively. Values of average radium equivalent activity, air-absorbed dose rate, indoor and outdoor annual effective doses, external and internal hazard indices and alpha index ranged from 6.5 to 124.9, 16.2 to 89.5 (nGy h(-1)), 0.08 to 0.44 mSv, 0.02-0.11 mSv, 0.09 to 0.53, 0.13 to 0.69 and 0.03 to 0.62, respectively. These values indicate a low dose. Therefore, the building materials used in the current study are quite safe to be used as building materials.     

Optische in situ Schichtdickenmessung in Bedampfungsanlagen. Optical in situ film thickness monitoring in coating systems

Optical film thickness monitoring is more precise than crystal monitoring. The optical measurement makes use of the fact that the intensity of a monochromatic light beam which is reflected on a film will change periodically with increasing film thickness. The measurement is performed at an exchangeable test glass that is positioned beside the substrates and is therefore coated in the same way as the substrates. The accuracy of cut‐off is achieved by a “fit” of a theoretical curve shape to the measured values. Order filters are used to ensure that, at a certain wavelength, higher deflection orders do not influence the measurement when a monochromator grating is used.