THE ROLE OF PORTCITIES OF THE WESTERN YELLOW SEA IN THE FUTURE DEVELOPMENT OF RELEVANT REGIONS

I.Introductionl.BasicfcatUresofportcitiesandthcirwhuencingfactorsTl1elhstoricalexperiencesofdevelopedcowtrieshavewitnessedtheessel1tialro1eplayedbyseaportsinpromotingdevelopn1entofnationaleconomy.Manyportcities,emergodfron1marinetransportation,supportedbyseaandlandroLrtesandflourishedn1ainlythroughindustryandtrade,oftenbecomendonalornationalecononhccenters.fu11ongti1eworld's2Omeqalopolesofmorethan6ntilIionpopulation,l2areportcities.AlmosteverycoUntrywiti1coastalline,longorshort,roprdsoneors…     

Energy dissipating restrainers for highway bridges

Recent destructive earthquakes have demonstrated the vulnerability of highway bridges to collapse due to excessive movement beyond the available seat widths at expansion joints. This paper investigates the efficacy of using energy dissipating restrainers at expansion joints for preventing collapse of highway bridges in the event of a severe earthquake. The restrainer consists of a nonlinear viscous damper and an elastic spring connected in parallel or in series. Two-dimensional finite element analysis using bilinear hysteretic models for bridge substructure joints and nonlinear gap elements for expansion joints is performed on example bridges with one or two expansion joints. The analytical study demonstrates that the energy dissipating restrainers are effective in reducing the relative opening displacements and impact forces due to pounding at the expansion joints, without significantly increasing ductility demands in the bridge substructures.     

Performance of geosynthetic reinforced soil bridge abutments with modular block facing under fire scenarios

This paper investigates the effect of fire on the performance of geosynthetic reinforced soil bridge abutments using experimental tests and finite element analyses. Experimental programs were comprised of a series of tensile strength tests at elevated temperatures and fire resistance tests, which were performed on a physical model. Findings revealed the adverse effect of fire on geosynthetic reinforced soil bridge abutments when fire duration exceeded 60 min. Results show that the depth within the backfill affected by the fire is approximately 50 cm.     

胜利黄河公路大桥震害预测研究

桥梁是生命线工程的重要组成部分,对桥梁作出符合实际的震害预测意义重大。以胜利黄河公路大桥为例,介绍了经验统计法、规范校核法、Push-over方法、大跨度桥梁定性和定量分析等桥梁震害预测方法。分别用Push-over(推倒分析)法和大跨度桥梁定性与定量相结合的震害预测方法对胜利黄河公路大桥进行了震害预测评价。     

新西海桥的非线性地震响应分析

本文讨论了日本第一座公路钢管混凝土拱桥——主跨230m的新西海桥的非线性地震响应特性。采用三维有限元计算模型,用纤维单元法考虑钢管混凝土的材料非线性,用P-δ效应考虑几何非线性,讨论了在纵桥向地震作用、横桥向地震作用以及纵、横桥两方向同时作用情况下该桥的非线性地震响应特性和抗震性能。计算表明,在纵桥向地震作用时轴力的作用显著,拱脚附近产生的内力较大;而横桥向地震作用时轴力和面外弯矩作用显著,拱脚以及拱肋与桥面连接附近产生的内力较大;横向地震响应远大于纵向地震响应;应考虑纵、横桥向地震力共同作用的影响。     

Local scour around bridge abutments under ice covered condition- an experimental study

The local scour around bridge abutments has been an active research topic for many decades. But very few studies have been conducted regarding the impacts of ice cover on the local scour phenomenon aro...     

特大桥钻孔灌注柱钻芯取样施工技术

结合贡嘎雅鲁藏布江特大桥钻孔灌注桩钻芯取样工程实例,阐述了在无法清理桩头、回填土层较厚的特殊条件下,成功钻取混凝土芯样的施工工艺.     

An experimental study of temperature effect on modal parameters of the Alamosa Canyon Bridge

Damage detection techniques have been proposed to exploit changes in modal parameters and to identify the extent and location of damage in large structures. Most of such techniques, however, generally neglect the environmental effects on modal parameters. Such environmental effects include changes in loads, boundary conditions, temperature, and humidity. In fact, the changes due to environmental effects can often mask more subtle structural changes caused by damage. This paper examines a linear adaptive model to discriminate the changes of modal parameters due to temperature changes from those caused by structural damage or other environmental effects. Data from the Alamosa Canyon Bridge in the state of New Mexico were used to demonstrate the effectiveness of the adaptive filter for this problem. Results indicate that a linear four-input (two time and two spatial dimensions) filter to temperature can reproduce the natural variability of the frequencies with respect to time of day. Using this simple model, we attempt to establish a confidence interval of the frequencies for a new temperature profile in order to discriminate the natural variation due to temperature. Copyright © 1999 John Wiley & Sons, Ltd.     

大瑞铁路澜沧江大桥工程边坡稳定性三维数值模拟分析

采用现场调查、工程地质分析和三维数值模拟方法,对在建大瑞铁路工程澜沧江大桥边坡稳定性进行了综合分析研究。澜沧江大桥是在建大瑞铁路的控制性工程之一,由于多种因素的综合作用,桥址岸坡发育延伸较长的顺坡向节理和近垂直的陡倾节理。右岸桥位工程开挖区位于一组较大型顺坡结构面的下方,岸坡稳定性直接关系到桥位的适宜性。综合研究表明,工程开挖后,右岸桥位上部岩体极易在顺坡向结构面的控制下发生滑移–拉裂式破坏,沿外倾结构面产生较大的位移,甚至可能失稳,需要进行专门的工程治理。左岸边坡岩体结构相对稳定,工程开挖后,位移将主要集中在开挖面附近的浅表层部位,不仅变形较小,影响范围也相对较小。      

The effects of uniform and nonuniform pile spacing variations on local scour at pile groups

Pile groups are frequently used to support bridge decks. Scour in the vicinity of piles is the main cause for the bridges failure. In this research, to address the effects of uniform and nonuniform pile spacing on the equilibrium scour depth, laboratory experiments were carried out under steady clear-water conditions. For this purpose, scour depth produced by pile group with various pile spacing and arrangement was investigated using a laboratory flume. Flume bed was covered by uniform sediments with a median size of 0.9?mm and 0.2?m thickness. Flow discharge and velocity as well as scour depth were recorded in each experiment and the data were analyzed. The results showed that the pile spacing influences the local scour depth and with increase in uniform and transverse (perpendicular to the flow) spacing, the maximum scour depth was reduced. The pile spacing variation in line with the flow has a minor effect on scour depth. In addition, the pile spacing perpendicular to the flow was with the most influences on scour depth. The results of this research can be used by engineers to optimize the design of bridges.