高墩大跨连续刚构施工监控控制技术分析

文章结合朝阳寺特大桥连续刚构工程施工监控实践,介绍了高墩大跨连续刚构桥箱梁施工监控控制技术的应用方法,并分析了该种监控技术的优势,为同类型桥梁施工监控提供参考。     

Not bored yet - Revisiting respondent fatigue in stated choice experiments

Stated choice surveys are used extensively in the study of choice behaviour across many different areas of research, notably in transport. One of their main characteristics in comparison with most types of revealed preference (RP) surveys is the ability to capture behaviour by the same respondent under varying choice scenarios. While this ability to capture multiple choices is generally seen as an advantage, there is a certain amount of unease about survey length. The precise definition about what constitutes a large number of choice tasks however varies across disciplines, and it is not uncommon to see surveys with up to twenty tasks per respondent in some areas. The argument against this practice has always been one of reducing respondent engagement, which could be interpreted as a result of fatigue or boredom, with frequent reference to the findings of Bradley and Daly (1994) who showed a significant drop in utility scale, i.e. an increase in error, as a respondent moved from one choice experiment to the next, an effect they related to respondent fatigue. While the work by Bradley and Daly has become a standard reference in this context, it should be recognised that not only was the fatigue part of the work based on a single dataset, but the state-of-the-art and the state-of-practice in stated choice survey design and implementation has moved on significantly since their study. In this paper, we review other literature and present a more comprehensive study investigating evidence of respondent fatigue across a larger number of different surveys. Using a comprehensive testing framework employing both Logit and mixed Logit structures, we provide strong evidence that the concerns about fatigue in the literature are possibly overstated, with no clear decreasing trend in scale across choice tasks in any of our studies. For the data sets tested, we find that accommodating any scale heterogeneity has little or no impact on substantive model results, that the role of constants generally decreases as the survey progresses, and that there is evidence of significant attribute level (as opposed to scale) heterogeneity across choice tasks.     

不对称连续刚构桥地震反应分析

文章以贵州省六盘山市一座不对称连续刚构桥为工程实例,利用结构分析软件MIDASCIVIL建立了该桥的有限元分析模型,并选用Taft波与时程分析法计算了该桥的地震响应情况。结果表明桥墩是地震作用下全桥受力最不利的位置,必须重视桥墩的抗震设计和验算。     

车桥耦合模型研究

文章推导了简支梁桥在移动荷载、移动刚体和弹簧质量块三种简化车辆模型作用下的车辆-桥梁系统振动微分方程,编制了基于龙格-库塔法的车桥耦合分析程序,并结合算例比较分析了简支梁桥在三种不同车辆简化模型作用下的动力响应。     

预应力混凝土连续梁桥体外预应力加固技术研究

从桥梁病害状况及原因分析、结构计算分析、加固构造措施的采用,到施工过程中的控制技术以及加固前后的荷载试验,详细地对预应力混凝土连续梁桥进行体外预应力加固技术研究。     

临吉东线S7光华中桥地震响应分析及抗震设计

临吉高速公路东线S7光华中桥为三跨装配式预应力混凝土连续箱梁桥,墩高相差较大。本桥址地震动峰值加速度为0.15g。针对该桥,分别从地震动输入、有限元模型的建立、抗震设计方案的选取以及桥梁结构的地震反应等几方面进行研究,对采取和不采取隔震技术的设计方案进行对比分析,最后推荐出较优的抗震方案。     

长江口12.5 m深水航道运行初期的疏浚效益评价

构建疏浚货运比、疏浚单方经济效益2个相对指标,同时结合疏浚土的综合利用,评价长江口12.5 m深水航道运行初期的疏浚效益。结果表明:2011—2015年长江口深水航道疏浚货运比趋于下降,已由运行首年的1 083 m~3/万t降至2015年的765 m~3/万t,降幅近30%。近5年来,深水航道疏浚单方经济效益增加明显,2015年已达到142元/m~3,远高于目前国内疏浚费用单价。同时,用于滩涂围垦的航道疏浚土数量相当可观,有利于控制疏浚和造地成本,实现提高长江口疏浚土利用率和增加上海市土地资源战略储备量的双赢局面。当前长江口12.5 m深水航道已进入全面发挥效益的稳定运行阶段。     

长江口12.5 m深水航道运行5年沪苏两地的效益响应

选择上海市及江苏省2个地区作为长江口深水航道受益对象,从宏观经济效益和社会效益2个层面分析评价长江口12.5 m深水航道运行5年沪苏两地的效益响应。结果表明,沪苏两地沿江港口的疏浚吞吐比整体有所下降,近5年降幅分别近15%和25%,2015年已分别减小至949 m~3/万t和327 m~3/万t。2011—2015年,沪苏两地因12.5 m航道产生的疏浚单方GDP增长量分别为目前国内疏浚成本单价的15~20倍和40~60倍,疏浚净效益相当可观。随着12.5 m深水航道江苏段的投入运行和沿江港口码头的改造升级,长江口深水航道的疏浚效益还将进一步增加。     

山区高速铁路桥梁经济指标分析

高速铁路建设中,会从工程实施的难易程度、线路方案中控制工程的多少、工程投资等多个方面出发,对多个可行性方案进行比较,以选定最合适的线路方案.其中,工程投资是线路方案决策的重要依据.高速铁路中桥梁占比大,为了快速给出桥梁工程投资,为方案决策提供依据,以某山区高速铁路为例,从桥墩平均高度、上部工程特殊结构占比、附属工程、施...     

赞比亚赞比西河特大桥钢梁拼装施工技术

赞比西河特大桥是赞比亚芒古塔博桥梁项目工程的控制性重点工程,主桥为(26.6+40+3×54+40+26.6)m钢—混结合梁桥.钢梁由2根工字钢板梁组成,间距5.5m,采用联结系连接.钢梁截面高度分别为1.6,1.6～2(变截面段),2,2～2.8(变截面段),2.8m,宽度均为0.8m.钢梁上部为预制混凝土桥面板,采...