电梯曳引轮失效模式分析及改进措施

随着我国城市化进程的不断加深,高层建筑大量建设,电梯作为这些高层建筑的交通工具,电梯的保有量越来越大。电梯的安全运行至关重要,受到广泛关注,随着电梯的长期使用,电梯曳引轮就容易受到磨损。曳引轮的失效直接影响电梯曳引能力,可能造成非常严重后果。本文通过分析电梯曳引式的失效模式及提出相应的改进措施,为电梯曳引轮运行失效问题提供帮助。     

电梯曳引钢带的失效分析及无损检测方法

介绍了曳引钢带的结构与应用优势,应用优势包括使用安全性高、使用寿命长、运行舒适性好、后续维护方便等。分析了曳引钢带的失效特征,以及加工工艺、安装工艺对曳引钢带性能的影响。探讨了应用多磁轭励磁装置对曳引钢带进行无损检测的方法。试验结果表明,多磁轭励磁装置的无损探伤检测技术能够满足曳引钢带的检测要求。     

电梯曳引条件拾遗

曳引式电梯的主传动路线是：电动机把旋转运动直接地（无齿轮）或间接地（有齿轮）传递到曳引轮轴，依靠曳引轮与钢丝绳之间的摩擦力来实现轿厢的上下运动。曳引轮与钢丝绳之间的摩擦副是曳引式电梯的传动系统中最具特色的传动环节，该摩擦副之间出现相对滑动即意味着传动失效。     

一则电梯曳引钢丝绳断裂案例的原因分析与防范建议

针对一则电梯曳引钢丝绳发生断裂的案例,通过现场观察、化学成分分析、破断拉伸试验、拆股试验、断口扫描电镜形貌分析、金相组织分析等方法,对钢丝绳两部分不同断口进行了断裂失效分析,得到了钢丝绳断裂的原因。最后,提出了防范曳引钢丝绳断裂的建议。     

浅析电梯曳引机曳引轮绳槽槽形

电梯曳引轮是曳引机上的绳轮，是电梯传递曳引动力的装置。电梯通过曳引钢丝绳与曳引轮缘上绳槽的摩擦力来传递动力。也就是说，驱动电梯运行的曳引力是依靠曳引钢丝绳与曳引轮绳槽之间的摩擦产生的。为减少曳引钢丝绳在曳引轮绳槽内的磨损并最大限度地提高曳引摩擦力，除了选择合适的绳槽槽形外，对绳槽的工作表面的粗糙度、硬度也应有合理的要求。在本文中笔者根据曳引轮有关特性及要求，仅从曳引轮绳槽槽形方面来探讨曳引轮的设计。     

夹绳器的作用、分类及构造

1夹绳器的作用 对于曳引驱动的电梯系统,上行超速和下行超速的风险几乎是一样的,正如依靠限速器一安全钳系统防止电梯的下行超速一样,也必须有专门的上行超速保护装置来防止电梯的上行超速。在某些情况下曳引驱动电梯可能会出现上行超速的危险,这些情况至少包括：曳引系统部件（如曳引机、制动器、轴、减速齿轮、联接器等）的失效;驱动控制系统失控等。美国是较早规定电梯上必须装设上行超速保护装置的国家,     

—起施工升降机坠落事故分析

分析了一起钢丝绳式货用施工升降机曳引轮与电机轴的连接失效、断绳保护装置（防坠器）失效、停层防坠落装置捆绑使用而导致吊笼坠落事故,提出加强对施工升降机使用管理的建议。     

电梯曳引绳张力分析

通过对曳引绳张力的定义和设计要求的探讨,分析了曳引绳张力差的影响,阐述了影响曳引绳张力的各类因素;指出了曳引绳张力测量不确定度的来源;针对曳引绳张力测量中的一些问题,探讨了修订曳引绳张力差控制标准要求的可能,提出了改进曳引绳张力测量、评价的方法以及减小曳引绳张力差的措施。     

电梯钢丝绳使用寿命影响因素分析

随着国内电梯数量的迅猛增长,与人们生命息息相关的电梯安全问题越来越受到社会广泛的关注,由于在电梯可能发生的事故中,“坠落”、“磨损”、“悬挂装置的破断”、“曳引轮上曳引绳失控滑移”等均有可能发生在钢丝绳上,因此本文就电梯钢丝绳的失效原因和提高电梯钢丝绳的使用寿命进行如下探讨。     

载货电梯曳引钢丝绳条数的优化设计

根据GB/T 7588.1/2-2020对曳引钢丝绳安全系数和曳引条件的要求,结合载货电梯现有配置和曳引条件,选择合适的影响曳引钢丝绳安全系数的关键参数——绳槽角度、曳引轮直径及钢丝绳直径,从而对曳引钢丝绳的条数进行优化设计。最后介绍了一个优化设计案例。     

无效建设工程施工合同结算实务初探

以无效建设工程施工合同条件下的结算实务为课题,结合结算实务中存在的问题,通过研究最新相关法律法规、司法解释、典型案例,为建筑企业无效建设工程施工合同条件下的结算问题提供解决方案,化解企业经营风险及法律风险。     

基于DEA 改进模型的建筑企业效率评价研究 ——以黑龙江省为例

为了提高黑龙江省建筑企业经营效率,采用DEA 改进模型,对黑龙江省9 种不同性质建筑企业的效率进行研究,针对多个同时相对有效的企业用改进的DEA 方法（IDEA）进行区分并排序。结果表明:占黑龙江省建筑企业投入比重最大的国有企业和集体企业的相对效率要低于港澳台商投资企业、股份合作企业和外商投资企业;国有企业和集体企业的技术效率是相对有效的,但规模效率是递减的。对于无效的建筑企业,从技术效率和规模效率两个方面分析其无效的原因,并从资金投入、技术创新、人员培训、组织管理等角度提出改进的建议。     

城市地下快速路驾驶模拟仿真试验方法研究

城市地下快速路具有设计指标宽容性低、多点进出、交通组织复杂等特点。针对待建的城市地下快速路,如何通过科学的方法获取地下快速路车辆运行数据是当前研究的难点。首先,结合城市地下快速路BIM模型,介绍高逼真驾驶模拟场景搭建过程及常见问题解决方法;随后,针对试验行驶路径、交通流量等要素制订驾驶模拟试验方案;最后,计算合理的试验样本数,利用试验获得的数据,提出驾驶模拟数据分析流程与方法。为了充分探究驾驶模拟仿真试验设计方法,通过驾驶模拟手段获得城市地下快速路驾驶行为数据,可为地下快速路驾驶行为特性研究、安全性评价及运营管理策略制订提供支撑。     

Does Compact Development Make People Drive Less?

Problem, research strategy, and findings: Planners commonly recommend compact development in part as a way of getting people to drive less, with the idea that less driving will lead to more sustainable communities. Planners base their recommendations on a substantial body of research that examines the impact of compact development on driving. Different studies, however, have found different outcomes: Some studies find that compact development causes people to drive less, while other studies do not. I use meta-regression analysis to a) explain why different studies on driving and compact development yield different results, and b) combine different findings from many studies into reliable statistics that can better inform planning practice. I address the following questions: Does compact development make people drive less, and if so, how much less? I find that compact development does make people drive less, because most of the compact development features I study have a statistically significant negative influence on driving. The impact, however, is fairly small: Compact development features do not appear to have much influence on driving. My findings are limited to some extent because they are derived from small sample sizes.

Takeaway for practice: Planners should not rely on compact development as their only strategy for reducing driving unless their goals for reduced driving are very modest and can be achieved at a low cost.     

混凝土结构耐久性初探

针对混凝土结构耐久性失效现象，对混凝土结构耐久性问题的本质及产生的原因进行了分析，指出影响耐久性的主要因素，并提出了提高耐久性的相应措施。     

The Driving Downturn: A Preliminary Assessment

Problem, research strategy, and findings: We examine why American driving fell between 2004 and 2013, weighing two explanations: that Americans voluntarily moved away from driving (“peak car”), and that economic hardship reduced driving. We analyze aggregate data on travel, incomes, debt, public opinion, and Internet access. These data lack the precision of microdata, but unlike microdata are available annually for years before, during, and after driving’s decline. We find substantial evidence for the economic explanation. During the downturn the cost of driving rose while median incomes fell. The economy grew overall, but did so unequally. Mass driving requires a mass middle class, but economic gains accrued largely to the most affluent. We find less evidence for “peak car.” If Americans voluntarily drove less, they would likely use other modes more. However, despite heavy investment in bicycle infrastructure and public transportation in the 2000s, demand for these modes remained flat while driving fell.

Takeaway for practice: If Americans were voluntarily abandoning automobiles for other modes, planners could reduce investments in automobile infrastructure and increase investments in alternative mobility. Driving’s decline, however, was not accompanied by a transit surge or substantial shift to other modes. The lesson of the driving downturn is that people drive less when driving’s price rises. Planners obviously do not want incomes to fall, but they should consider policies that increase driving’s price. Planners might also rethink the current direction of U.S. transit policy; transit use did not rise even when driving fell at an unprecedented pace.     

The Road Less Driven

Americans gain tremendous benefits from their driving in the form of access to opportunities. But the benefits do not come without burdens, for individuals and for society. To manage those burdens, transportation planners should focus on strategies that selectively reduce driving in two ways: by making it possible to drive less through land use policies and investments in non-auto infrastructure, and by discouraging less important driving with pricing policies. But merely layering a “drive less” approach on top of traditional efforts to make driving easier doesn't make sense. A more effective blend of strategies is needed.     

不同TBM掘进速率下洞室围岩开挖扰动区研究

 在不同卸荷速率下三轴加卸载室内试验成果的基础上,以Hoek-Brown经验强度准则为依据,拟合出在不同卸荷速率下板岩的力学参数(黏聚力和内摩擦角)。在分析TBM掘进特点的基础上,提出能反映其特点的数值模拟方法,并在FLAC3D程序中引入加卸载准则,对不同掘进速率下隧洞围岩的开挖扰动效应进行数值模拟研究。结果显示：掘进速率越快,围岩开挖扰动效应越小,围岩越稳定;隧洞围岩在开挖后变形较为均匀;在隧洞的径向,位移和应力变化较为明显的呈现为3个区域,即强变化区、弱变化区和平稳区;最大主应力随着洞径方向逐渐由单向应力状态向二向应力状态和三向应力状态转变,第二偏应力不变量在隧洞轴向方向形成一闭合的应力集中区域,称为“应力墙”,该区域在TBM掘进过程中对刀头切割岩体达到破岩的效果极为有利;隧洞围岩开挖扰动区随TBM掘进速率变化较大,当掘进速率增加一倍后,其扰动区由1.1 m降低到0.4 m,减小了64%。     

Estimation of building components' exposure to moisture in Greece based on wind,rainfall and other climatic data

An estimation of moisture loading severity for building components in Greece was attempted. Annual driving rain indices were calculated for 31 stations spread all over the country, based on the average annual rainfall and wind speed values derived from data, published by Hellenic National Meteorological Service. The analysis revealed that the majority of the locations are sheltered from driving rain. A driving rain map for Greece was produced. A second set of annual driving rain indices were calculated for these sites, based on average monthly data. The relationship between these two sets of indices for the 31 locations was best approximated by a hyperbolic function. Thessaloniki, a city in northern Greece, was further studied using average annual and daily data provided by the Institute of Meteorology and Climatology, A.U.Th. For Thessaloniki, the exposure estimated from daily data was bigger than the one resulting from annual data. Finally, a moisture index for the comparison of building components' exposure to moisture, with the drying potential also being considered, was calculated for the 31 sites studied and a ranking of these sites' climates in terms of moisture loading on buildings was obtained. The drying potential's contribution to this ranking is very important.     

A look at driving rain intensities at five cities

In this article, maximum hourly driving rain intensities calculated from hourly wind and rainfall data for five cities, three in Great Britain and two in Norway, are examined and comparisons are made with average annual driving rain values, also from hourly wind and rainfall data. The results show that the maximum observed driving rain intensities versus wall angle are quite different from angular distributions of annual driving rain both at and between the stations. For driving rain intensity expressed as the average number of exceedances of a threshold intensity value versus wall angle, on the other hand, results are qualitatively and quantitatively very similar to angular distributions of annual driving rain. This suggests that average annual driving rain might be useful as a surrogate measure of driving rain intensity in situations where relative risk of repeated rain penetration of doors, windows and other openings in building facades is of interest but long series of hourly wind and rain data are not available.