共查询到20条相似文献,搜索用时 109 毫秒
1.
2.
空间网架结构是一种比较新型的结构形式,具有整体性和稳定性好、空间刚度大、安全度高、自重轻、用钢量省、运输安装方便等优点,使其很快被人们所认识。据不完全统计,全国已有1500多座各种不同类型的网架结构建筑,总建筑面积约150万m~2。 常用的网架形式有平板网架、曲面网架、球形网架等,以平板网架为最多。常用的网格形式为两向正交、三角形、锥形、蜂窝型等,以两向正交和锥形网格为多。常用的网架节点有十几种,目前我国普遍推广应用的节点形式有三种,即螺栓球节点、焊接球接点和钢板节点。已建成的网架结构大约有1000座左右采用螺栓球节点,300座左右采用焊接球节点,200座左右采用钢板节点。螺栓球节点及其杆件大都在网架厂生产,运到现场安装;焊接球节点也在专业厂生产。 (一)网架结构的优点 网架结构之所以得到越来越广泛的应用,成为当代建筑技术的发展潮流,是因为它具有明显的优越性。 相似文献
3.
网架结构的施工与监理 总被引:2,自引:0,他引:2
网架结构以其自重轻巧、方便安装、结构新颖、施工迅速,可大跨度组合,可整体或分段顶升施工等优越的施工工艺和使用功能,越来越多地被人们利用在大型体育场馆、机场、会堂等重要公共建筑之中。如大连机场候机楼、大连人民体育场看台、大连杂技馆、大连马家军训练基地等工程,都使用了网架结构。但在网架工程中,如果不严格按施工规范组织施工,不严格按检查 相似文献
4.
5.
在研究论述飞机燃油系统设计中高空性的基础上,通过分析燃油的饱和蒸汽压的影响因素,给出了燃油饱和蒸汽压的计算公式和燃油的饱和蒸汽压力随温度的变化曲线,并给出了航空煤油能够保证的飞行高度;讨论了燃油系统的汽蚀问题;分带供油泵管路和无供油泵管路2种情况讨论了燃油系统高空性计算流程,并给出了具体的计算公式和图表。 相似文献
6.
7.
8.
本输煤工程圆形煤场共两座,网架形式为正放四角锥球面网架,下弦周边点支承,网架支座采用单向滑动支座,支座间跨度为124.35 m。对于本球形网壳采用先起步单元安装形成闭合结构,然后以闭合结构作为支撑体系,采用环向散装小拼单元的方法安装后续网架。 相似文献
9.
10.
11.
12.
热冲压成形制造高强钢零件是实现汽车轻量化的有效途径。现有热成形零件强度高但塑性低,如何在保持零件高强度同时,提高其塑性是热冲压成形发展的方向,而这需要对热成形过程微观组织演变进行更加深入的研究。相比于试验手段和理论分析,数值模拟能够更直观、更全面地反映热成形过程零件宏观的温度、应力变化历程,以及微观组织演变。总结了现有的热冲压成形过程的宏观温度场及应力场以及微观组织演变过程的模拟研究,并对今后的研究进行了展望。该方向的研究可为高强钢热冲压成形提供理论基础及技术支持,有助于汽车轻量化的实现。 相似文献
13.
14.
为解决高铬钢复合轧辊离心复合铸造生产中的结合层夹渣问题,以复合铸造过程数值模拟与夹渣物XRD分析相结合,分析了该夹渣成分及分布原因。首先,通过宏观检查并利用XRD实验定性分析了夹渣物的组成,初步确定了夹渣物为生产中高温反应生成的非金属夹渣,且集中分布于辊身冒口端。其次,采用数值模拟的方法分析了高铬钢轧辊复合铸造的生产过程,对比研究了离心铸造和重力铸造2个阶段辊身冒口端与底端的高温金属流动与温度场演变差异。模拟结果表明:芯部重力铸造时,芯部高温金属液对轧辊外层冲刷作用的差异是夹渣物主要分布于辊身冒口端的重要原因。通过复合铸造过程流场与温度场的模拟结果,对高铬钢复合轧辊结合层夹渣物的产生和分布原因进行分析,对于改善离心铸造轧辊缺陷的产生具有借鉴意义。 相似文献
15.
为了简化现有静承载力的评估测算过程,提高实际工程中的施工效率和可靠性,提出了一种简单实用的桩基静承载力分析方法。通过测定现场钢管桩打入过程中桩头加速度以及整体应变波形的数据,得到最大锤击能量和最大桩头贯入度;利用准静态分析法计算得到钢管桩的静承载力,并将此计算结果与实际测定值进行对比验证。结果表明:1)通过锤击钢桩激发冲击波求得的最大静承载力与设计容许承载力基本一致;2)桩先端部到达坚实层时,所受最大冲击力约为设计容许承载力的1.9倍;3)通过控制打桩时的锤击次数可以对钢管桩的贯入度进行施工管理。研究提出的静承载力分析方法是可行的,能够为钢管桩的打桩施工提供更多的选择,为桩基施工技术管理优化提供参考。 相似文献
16.
17.
18.
Implementing the lead user method in a high technology firm: A longitudinal study of intentions versus actions 总被引:3,自引:0,他引:3
The customer or user's role in the new product development process is limited or nonexistent in many high technology firms, despite evidence that suggests customers are frequently an excellent source for new product ideas with great market potential. This article examines the implementation of the Lead User method for gathering new product ideas from leading edge customers by an IT firm that had not previously done much customer research during their new product development efforts. This case study follows the decision‐makers of the firm through the process, where the end result is the generation of a number of useful product concepts. Besides the ideas generated, management at the firm is also impressed with the way the method makes their new product development process more cross‐functional and they plan to make it a part of their future new product development practices. Approximately one year later the firm is revisited to find out if the Lead User method has become a permanent part of their new product development process. The authors find, however, that the firm has abandoned research on the customer despite the fact that several of the lead‐user derived product concepts had been successfully implemented. Management explanations for their return to a technology push process for developing new products include personnel turnover and lack of time. Using organizational learning theory to examine the case, the authors suggest that the nontechnology specific product concepts generated by the lead users were seen as ambiguous and hence overly simplistic and less valuable by the new product development personnel. The technical language spoken by the new product personnel also increased the inertia of old technology push development process by making it more prestigious and comfortable to plan new products with their technology suppliers. The fact that the firm was doing well throughout this process also decreased the pressure to change from their established new product development routine. The implications for these finding are that: 1) it is necessary to pressure or reward personnel in order to make permanent changes to established routines, and 2) researchers should be careful at taking managers at their word when asking them about their future intentions. 相似文献
19.