预应力混凝土曲线梁桥的扭转效应研究

小半径预应力混凝土曲线梁桥存在明显的扭转效应,可能导致梁体剪应力大、扭转变形大和内外支座反力差大。文章提出了扭转效应的五种导致因素,并结合一联曲线箱梁实例,计算分析了各种因素所产生扭矩的大小与分布情况,进而探讨了扭矩对梁应力和支座反力的影响,最后总结了曲线梁桥的抗扭设计要点。     

剪力柔性梁格法应用要点探讨

迄今为止,计算异型桥、斜弯桥等箱梁桥最有效的计算方法就是剪力柔性梁格法。但梁格法毕竟是在满足一定条件的空间问题,因此从建立模型、大量原始计算数据的准备,还是需要比较长的时间。本文对梁格法的历史背景、计算理论及计算方法进行详细的阐述探讨,希望能够对桥梁设计者对梁格法有更加深入明确的认识,并在一定程度上能够推进梁格法的应用。     

曲线桥的病害及防治对策

曲线梁能够适应复杂路况的需要，是现代交通工程中的一种重要桥型。但由于曲率的影响，曲线梁易产生弯扭耦合作用，因此曲线桥的内力、变形计算远比直线梁桥复杂，实际工程中易产生问题。文章系统阐述了曲线梁桥的常见病害及原因，提出了防止病害产生的处治措施，为曲线桥的维修与加固提供方法依据。     

混凝土箱梁桥剪力滞效应分析

文章结合工程实例,介绍运用平面杆系法和空间梁格法分别进行建模计算的方法,分析结构在白重、预应力等恒载作用下剪力滞效应分布的特点,讨论了目前工程中常用的有效分布宽度法的不足,并提出了相应的修改意见。     

剪力-柔性梁格法在槽形梁内力分析中的应用

文章结合某公路工程槽形梁施工图设计工程实例,运用有限元软件Midas Civil 2015对槽形梁分别采用剪力-柔性梁格法和梁单元法进行建模计算,比较分析这两种方法结构内力计算结果的差异,结果表明:空间梁格模型横向分布关系明确,模拟更为准确,计算结果较为精准,设计更为准确,工程造价更经济,更适用于槽形梁的结构计算。     

曲线梁桥设计时冲击系数的确定

由于曲线梁桥有别于直线梁桥的特殊结构,冲击系数确定与直梁桥区别较大.对曲线梁桥在车辆荷载作用下的冲击系数确定做简要的分析,并进行了实例计算论证.     

常规桥梁平面梁格法模型横向刚度的精确调整方法

荷载试验最主要试验对象为常规桥梁(T梁、小箱梁、空心板)。为了得到控制梁片在设计荷载下的计算挠度和应变,通常采用平面梁格法模型进行计算,然而,模型中横向联系刚度模拟的不准确,会使现场对试验结果的判断产生偏差,使桥梁缺陷无法及时被诊断。文章以大量荷载试验得出的试验数据为根据,提出用平面梁格法模型建立常规桥梁时更精确的横向联系建模调整方法。     

公路装配式梁桥布梁设计探讨

公路装配式梁桥为适应不同平曲线线型,需采用不同的布梁方案,以利于标准化设计和施工。本文针对公路装配式梁桥采用的两种布梁方式,展开分析其各自的适用范围,以方便设计者加深对装配式梁桥布梁方案的理解,减少因布梁方案的错误而引起的不必要的施工麻烦。     

梁格法在T型梁桥静载试验中的应用研究

桥梁荷载试验能够直观地反映桥梁承载能力,而理论计算的准确性直接影响着桥梁荷载试验的安全性和结构的可靠性,因此,使用合理的方法进行桥梁结构荷载试验计算显得尤其重要。文章基于Midas有限元分析软件,采用梁格法对某T型连续梁进行荷载试验分析,结果表明:梁格法可以简单直观地反映空间结构的受力状况,便捷地调整横向弯矩传递有效值以反映出结构的实际受力状况。该方法在荷载试验中的应用具有较高的实用性和准确性。     

某小半径曲线箱梁桥动力特性及地震反应分析

曲线梁桥的平面不规则性引起的弯扭耦舍效应,导致其动力特性及地震反应的复杂性.本文结合某高速公路互通匝道R=60m的小半径曲线箱梁桥的工程实例.采用MIDAS间有限元分析软件,对该曲线梁桥的动力特性及地震反应进行了分析、计算.其分析过程与结果可为同类工程提供参考.     

Analysis of factors affecting the choice of route of pedestrians

Pedestrians as compared to vehicular traffic enjoy a high degree freedom of movement even in heavily congested areas. Consequently, there are more alternative links available to pedestrians between a given origin‐destination (O‐D) pair. This paper describes a study done by the University of Calgary to evaluate the factors affecting the choice of route on intra‐CBD trips or trips within the Central Business District (CBD).

An origin destination survey conducted in downtown Calgary, Alberta enabled the identification of the most significant factors influencing the choice. These factors were analyzed in relation to the physical characteristics of the location, personal characteristics of the trip maker and the type of the trip.

It appears that most people chose the shortest link and factors such as the level of congestion, safety or visual attractions were only secondary. This suggests that the length should be made a major consideration when planning and designing pedestrian links.     

实现多组态计量软件集中监控的可行性分析

天然气自动计量系统有多种组态软件,由于软件的不相通性,造成了计量系统数据采集的通用性差、数据传输与入库的时效性差、数据利用的可靠性低.结合各组态软件的实际情况,从设计上充分利用Oracle大数据处理能力以及Partition(分区表)的特性,实现历史数据的存储,应用WebService与COM+数据访问组件提供多层数据访问架构,采用OPC与DDE工业数据交换协议,实现了各站场计量数据的实时上传,为连续数据采集和实时监控提供了可能,节约了改造成本.     

注汽管道承压能力评估和实物试验验证

基于失效评估图技术对某注汽管道进行了承压能力评价,给出了管线在不同腐蚀壁厚情况下的极限承压能力和极限裂纹尺寸。并利用实物爆破试验验证了评价方法的安全性和有效性,通过对爆破断口进行宏观和微观分析,发现管段的开裂属于脆性开裂。     

Non-parametric analyses of efficiency of airports

This paper estimates the efficiencies and productivity changes of 12 international airports in the Asia-Pacific region based on data from 1998 to 2006. We apply stochastic frontier analysis (SFA) to compute efficiency estimates and use the Malmquist productivity index (MPI) to analyze productivity changes. We use the SFA model with a translog-type production function after testing the statistical hypotheses. According to the results of the SFA hypothesis tests, airports have experienced a technological regression; the deviations from the efficiency frontier are caused more by technical inefficiency than random noise. However, the inefficiency was found to decrease. The MPI reveals a declining trend resulting more from technological change than from efficiency change, with a decrease in inefficiency. Taken together, both the hypothesis tests and the MPI not only provide consistent conclusions, but also suggest that airports should concentrate on technological progress.     

波纹管应力分析研究进展

评述了波纹管应力理论研究方法的进展情况，围绕解析法、工程近似法和数值法，对波纹管理论研究中的一些主要成果作了较详细的回顾和总结，对各种研究方法作出了评价，展望了亟待解决的一些问题。     

输油管道中原油乳状液的流变性研究

原油乳状液的流变性是原油开采后在管道中输送的重要研究方面,为了更好地研究这一性质,采用电动搅拌机、偏光显微镜以及流变仪等仪器来测定不同含水率的原油乳状液在不同条件下的黏度,观测不同含水率的原油乳状液在偏光显微镜下的形态。并且分别对原油乳状液的黏度与含水率之间的关系以及与剪切速率之间的关系进行研究,初步确定了所测区块原油乳状液的转相点以及该区块原油乳状液的流变特性,为生产中的油气集输提供了理论依据。     

埋地管道防腐保温层失效评价

明确埋地管道防腐保温层的技术评价标准,对埋地钢质管道的安全运行,延长管道使用寿命具有重要意义。为了对埋地管道防腐保温层做出有效评价,从间接检测与开挖检测2个方面,结合现场检测数据,提出了基于防腐保温层的电流衰减率、绝缘电阻率、质量状况与厚度的分级评价标准及基于4种评价指标的综合评判方法。工程实践表明,该评价标准对防腐保温层是否存在失效能做出有效判断。     

城市轨道交通杂散电流监测系统概述

介绍了城市轨道交通工程中杂散电流不同的监测系统的构成,分析了集中式、分散式和智能型等监测系统的配置和功能,以及智能型实时在线监测系统的重要意义,为轨道交通工程杂散电流监测系统的选择与应用提供参考。     

Preliminary results of an analysis of areas of influence in Shanghai

The main deficiency of most current modeling approaches to transportation can be identified as neglect of the integration of existing geographical knowledge in regard to the ex ante transport/land use modeling approaches, with its focus on territorial dynamics and theory development. This paper addresses this aspect of the problem by introducing a theoretical and methodological framework for the analysis of the interrelationship between land uses. The analysis attempts to determine to what extent the functional land use in a city can be considered an ordered pattern. The order sought does not rely on purely spatial configurations, but on the correlation of transportation and land use. The first section of this paper focuses on theoretical considerations. It stresses the fact that conventional approaches do not apply in the present context. It then suggests an alternative based on areas of influence and measured in terms of level of attractance of land uses. The second describes a procedure based on this alternative following the remarkable contribution of Hanjoul, Beguin and Thill. An application of this procedure to the analysis of Shanghai is then examined. Finally, an evaluation of the strategies for optimizing the interrelationship between land uses is presented. The paper concludes with a possible research agenda.     

Direct analysis of the perceived importance of attributes of reliability of travel modes in urban travel

Reliability of travel modes was found to be the most important characteristic of transportation systems in several attitudinal investigations of individual travel behavior. This paper represents the first part of a research effort aimed at gaining a better understanding of the characteristics of reliability of transportation modes in urban travel. In this research, reliability characteristics are identified; their importance relative to each other is assessed, and an insight into possible structure of an objective reliability index is discussed. The research is based on perceived values of reliability, which were identified through a large attitudinal survey conducted in the Chicago metropolitan area.