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Search Results: 1 - 10 of 303945 matches for " 综述<br>bridge engineering "
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预应力混凝土桥梁抗火研究综述

张岗,贺拴海,侯炜,KODUR V K
- , 2018,
Abstract: 为了促进中国桥梁工程抗火研究领域的全面发展,加快预应力混凝土桥梁的抗火研究,回顾了国内外桥梁火灾的典型事故以及发生特点,强调了油罐车火灾对桥梁结构威胁的严重性,总结了预应力混凝土桥梁的火灾特点,对其抗火研究存在的问题进行了梳理,包括其材料高温特性、高温爆裂现状,火灾下桥梁预应力的存在状态及其试验与测试方法,火灾全过程中预应力混凝土桥梁力学性能的数值模拟与仿真,预应力混凝土桥梁的耐火极限,火灾后预应力混凝土桥梁的损伤评估加固及桥梁抗火研究的工程应用。从性能退化机理与极限垮塌行为、复合单元的研发与计算机仿真技术、收敛点的获取、火灾试验方法与测试技术、损伤评估精准模型和抗火设计方法的提出,五大方面给出了预应力混凝土桥梁抗火研究亟待解决的问题和更新目标,以期对桥梁工程抗火方向的学术研究提供新的视角和基础资料。
To promote the comprehensive development of fire resistance in bridge engineering in China, and accelerate the research on fire resistance of prestressed??concrete bridges, some typical fire incidents of bridges occurring at home and abroad, as well as fire characteristics, were reviewed. The severity of oil tankers as threats to bridge structures was emphasized, and the characteristics of prestressed??concrete bridges exposed to fire were summarized. Thereafter, the status of research on the fire resistance of prestressed??concrete bridges was examined. This included the high??temperature properties of materials used for prestressed??concrete bridges, the spalling feature of prestressed concrete at elevated temperatures, the service status of prestress in concrete bridges under fire exposure conditions, a test and measurement method of prestressed concrete bridges exposed to fire, a numerical analysis and simulation method of the mechanics in prestressed??concrete bridges during fires, the fire resistance of prestressed??concrete bridges, damage evaluation and strengthening methods for prestressed??concrete bridges after fire, and engineering applications. Finally, problems based on five aspects were proposed that remain to be solved in fire??resistance research for prestressed??concrete bridges,such as performance degradation mechanism and ultimate collapse behavior, compound element development and computer simulation techniques, the point of convergence,testing techniques in fire tests and measurement methods, a precise model of damage evaluation, and a fire resistance design method. A new perspective and basic information for the academic research on the fire resistance of bridges are expected
焊接管节点疲劳研究综述
Review of Fatigue Behavior in Welded Tubular Joints

刘永健,,,王康宁
- , 2017,
Abstract: 为加深对焊接管节点疲劳问题的认识,对焊接管节点名义应力法、热点应力法、切口应力法和断裂力学法4种常用疲劳评估方法应用现状和存在问题进行介绍,从疲劳效应(热点应力集中系数)和抗力(热点应力幅??S??N??曲线)2个方面对首推的热点应力法研究现状进行总结,探讨了管节点结构形式的发展趋势。结果表明:焊接管节点常用四大疲劳评估方法中名义应力法应用最广,但过于保守,热点应力法最被推崇,但仍有待进一步完善,切口应力法实施难度大,尚未在规范中使用,断裂力学法则适用于剩余疲劳寿命评估;对于传统的圆形和矩形钢管节点,已形成了较为系统的热点应力评估方法,对热点应力集中系数最大值可能发生位置、外推区域、热点应力集中系数计算公式、壁厚效应修正系数等方面进行了明确的规定;在传统的圆钢管和矩形钢管节点基础上,创新节点形式,提出了钢管混凝土节点、PBL加劲型钢管混凝土节点、圆管?卜焦芙诘愫湍褡焓浇诘悖?对比传统钢管节点,钢管混凝土节点热点应力集中系数降幅在25%以上,PBL加劲型矩形钢管混凝土节点降幅在50%以上,圆管?卜焦芙诘愫湍褡焓浇诘憬捣?则介于圆形钢管和矩形钢管节点之间。
In order to deepen the understanding of fatigue problem of welded tubular joints, the application status and existing problems of four frequently used assessment approaches including nominal stress approach, hot spot stress approach, notch stress approach and fracture mechanics approach were introduced. The current research of hot spot stress approach, which was the most suggested, was summarized in the aspects of fatigue effect and fatigue resistance. The structural development trend of tubular joints was explored. The results show that in the four frequently used approaches, the nominal stress approach is the most widely used, but it is over??conservative. The hot spot strees approach is the most suggested and it needs to be perfected. The notch stress approach will be applicable in an assessment of residual fatigue life. The comparatively systematic hot spot strees approach is proposed for traditional circular and rectangular tubular joints, and possible position of maximum hot spot stress, extrapolation region, equations for hot spot stress concentration factor, thickness correction factors are specified. Based on the traditional circular and rectangular tubular joints, the structure of joints is innovated, and the concrete filled steel tube joints, concrete filled steel tube joints stiffened with PBL, circular hollow section??rectangular hollow section(CHS-RHS) joints, bird??beak square hollow section(SHS) joints are proposed. Comparing with traditional joints, the hot spot stress concentration factor of concrete filled steel tube joints and concrete filled steel tube joints stiffened with PBL reduce more than 25% and 50% respectively. The hot spot stress concentration factor of bird??beak SHS joints is between circular tubular joints and rectangular tubular joints
混凝土结构抗火研究综述与建议
Review and suggestion on fire resistance research of reinforced concrete structures

孙鹏,侯晓萌
- , 2018,
Abstract: 为了促进混凝土结构抗火研究的发展,从火灾温度场发展过程、混凝土结构抗火性能与抗火设计、火灾后结构损伤评估与加固修复、混凝土结构抗火性能提高方法等4个方面出发,总结混凝土结构抗火研究成果,指出研究中存在的问题并展望了其发展趋势。从空气、结构温度场2个方面归纳了火灾温度场研究方法,总结不同参数对混凝土材料、构件、结构高温性能的影响规律,分析现有混凝土结构抗火设计方法的应用以及其优点和不足,梳理火灾后结构损伤评估流程,分析火灾后实际工程损伤评估与加固修复案例,并对现有火灾后结构损伤检测和维修加固方法进行总结,最后,从材料及构造2个方面总结提高混凝土结构抗火性能的方法。研究表明:高温下混凝土结构力学性能劣化严重,掺加纤维、调整原材料配合比和应用合理构造措施可提高混凝土结构抗火性能,掺聚丙烯纤维可有效避免高性能混凝土高温爆裂。后续应重点研究高温下大空间混凝土结构温度场分布,材料高温性能随机性对混凝土构件力学性能的影响规律,不同温度?埠稍芈肪都胺锤瓷?降温对结构和构件高温性能的影响,科学的混凝土结构火灾损伤评估体系,结构抗火可靠度设计理论研究和高性能混凝土结构抗火设计方法等方面。
To promote the development of research of fire resistance of concrete structures, the four aspects of the development process were systematically summarized. Accordingly, the development of the temperature field of fire, fire resistance performance and fire resistance design of concrete structures, damage assessment and repair reinforcement of structures after fires, improvement of the fire resistance of structures, and some issues for each aspect that still need to be investigated were discussed, and the development trend of the research was also prospected. Among them, the research methods of the fire temperature field were summarized from the perspectives of air and structural temperature fields. The effects of different parameters on the high??temperature resistance performance of concrete materials, members, and structures were also summarized. Further, the application, advantages, and disadvantages of existing fire??resistance designs for concrete structures were analyzed, and the general process of structural damage assessment after a fire was examined. Engineering damage assessment and reinforcement repair cases after fires were also analyzed, and existing detection and repair methods after fires were summarized. Finally, methods for improving the fire resistance of structures were listed in terms of materials and construction. The results show that the mechanical properties of concrete structures deteriorate seriously at high temperatures. Adding fibers, adjusting raw materials, and construction measures can improve structural fire resistance. Further, adding polypropylene fibers can effectively prevent spalling of high??performance concrete. The following main subjects need further study, such as the temperature field distribution of large concrete structures under high temperature, the influence of the randomness of a material??s high??temperature performance on mechanical properties of members, the influence of different temperature??load paths, the effects of repeated lifting and lowering temperatures on the high??temperature performance of
Design Method of Small-scale Cable-stayed Bridge Based on Stiffness Similarity Theory
基于刚度相似原理的斜拉桥模型设计方法

XIANG Yi-qiang,WU Sun-yao,DUAN Yuan-feng,
项贻强
,吴孙尧,段元锋

实验力学 , 2010,
Abstract: Model test is one of the important means for evaluating structure performance. Currently, there are only a few researches about design method of small-scale cable-stayed bridge. General idea for small-scale cable-stayed bridge design method is presented in this paper, and similarity relation for static and dynamic model is derived. According to similarity relation, a three-span prestressed concrete small-scale cable-stayed bridge was virtually built, and comparison was made among the model and prototype numerical analysis and prototype field static and dynamic test results. Results show that for cable-stayed bridge that is one kind of combined structure, stiffness similarity method is suitable when there are two different elastic modulus similarity ratios. Finally, important problems concerned in small-scale cable-stayed bridge design are discussed to provide guidance for small-scale cable-stayed bridge design.
索夹对自锚悬索桥成桥状态影响分析
孙永明,张连振,李忠龙
- , 2016, DOI: 10.11908/j.issn.0253-374x.2016.01.004
Abstract: 基于有限单元法(FEMC)比较分析了索夹对自锚悬索桥成桥状态的影响.索夹能够提高中跨主缆的成桥线形,在维持索长不变的情况下,各吊杆的成桥索力会有所增大,若使各吊杆均达到设计成桥索力值,则需增大各吊杆的无应力长度值.基于计入索夹影响的FEMC模型分别讨论了索夹长度、截面面积和惯性矩等参数对结构成桥状态的影响,并且建立了根据索夹长度比和面积比计算得到的主缆中跨跨中控制点成桥高程提升量和吊杆索力平均增量值的简化计算公式.经工程实例验证,提出的索夹模型计算结果与结构实际变形接近.
The impacts of cable clamps on the completed state of a self anchored suspension bridge were analyzed based on the finite element method (FEMC). The cable clamp could raise the shape of main cable in a middle span. If the unstressed length of each boom was kept unchanged, the pulling force of each boom would increase. In the same way, if each boom was made to reach the designed force on the completed stage of a bridge, the unstressed length of each boom should be increased. Based on FEMC, the impacts of parameters, e.g. length, cross sectional area and moment of inertia on the completed state of a bridge, were studied respectively. Furthermore, the simplified formulas were established, which could calculate the elevation increment of mid position of main cable in the middle span and the average increment of each boom force by the length ratio and area ratio of cable clamp. It is verified that results from FEMC are in good agreement with the measured data
近场地震下深水桥墩响应特性及动水效应计算方法检验
Response property of deep-water bridge pier under near-fault earthquakes and inspection of calculation methods of hydrodynamic effect

江 辉,王宝喜,白晓宇,,??,曾 聪
- , 2016,
Abstract: 动水效应是深水桥梁抗震设计中需要考虑的重要问题,而近场地震下深水桥墩的响应特性及合理计算方法亟待研究。以某典型深水桥梁为对象,基于可有效考虑墩?菜?流固耦合效应的完全数值计算方法,建立其等效单墩模型。首先讨论了水域范围对结构自振频率计算结果的影响,然后分析了不同水深下桥墩自振特性及脉冲型近场地震下的响应特征,并检验了几种代表性的解析?彩?值方法的准确性。研究结果表明:当水域宽度达到桥墩直径的10倍时,自振频率计算结果保持稳定;桥墩自振频率随水深增大而减小,桥墩完全被水淹没时前3阶自振频率分别比无水时减小了5.3%、12.2%和17.9%;不同方法下各阶频率的误差率随水深增大总体呈增大趋势,日本规范所得频率偏大,最大误差率超过20%,Morison方程法所得频率偏小,辐射波浪理论、中国铁路规范所得频率值与流固耦合数值法接近;近场地震下,桥墩弯矩、剪力和位移响应比无水时分别增大了22%、23%和20%,Morison 方程法计算结果偏大,其最大误差率超过6%,日本规范计算结果偏小,最大误差率接近-5%,辐射波浪理论、中国铁路规范及李乔?惭钔蚶砑蚧?公式所得结果与流固耦合完全数值法相吻合,5种方法均可适用于一般尺度深水桥梁的抗震设计。研究成果对于近断层区深水桥梁的抗震设计具有借鉴意义。
Hydrodynamic effect is an important issue which should be taken into account in seismic design of deep-water bridges, and the response property of deep-water bridge pier under near-fault earthquakes and its reasonable computation method needs to be studied. Therefore, taking a typical deep-water bridge as research subject, this paper built the equivalent pier model based on complete numerical method considering fluid-structure interaction. The influence of water range on stability of results was analysed firstly. Then the vibration and response characteristics of the deep-water pier excited by impulsive near-fault ground motions were discussed. Furthermore, the accuracy of several typical analytical-numerical methods was checked. The results show that the vibration frequency tends to be stable when the water width is 10 times of pier’s diameter. The vibration period and dynamic response of pier is amplified by hydrodynamic effect, and this influence becomes more significant with the increase of water depth. The first three vibration periods of pier with full-water around increase by 5.3%, 12.2% and 17.9%, while the maximum bending moment, shear force and displacement increase by 22%, 23% and 20% respectively under near-fault earthquake. The error rates of different methods vary with the change of water depth. The calculated response by Morison equation method is larger than that by complete numerical method, and the error rate is beyond 6%, while that by Japanese code is smaller and its error rate is close to -5%. The calculated results by radiation wave theory, Chinese railway code and LI Qiao-Yang Wan-li’s formula are quite close to that by complete numerical method, which means these methods are applicable to deep-water bridge of usual sizes. The above research results could provide reference for seismic design of deep-water bridge near active fault zone
RESEARCH PROGRESS OF REFERENCE ELECTRODE FOR ENGINEERING
工程用参比电极的研究进展

ZHANG Ling-ling,DU Min,YAN Min,
张玲玲
,杜敏颜民

腐蚀科学与防护技术 , 2006,
Abstract: Cathodic protection system is one of the important corrosion control technologies, while the reliability of reference electrode will influence directly the accuracy of parameters measured for the system. Conventional reference electrodes are inconvenient for field application. Therefore, developing a reference electrode suitable for engineering purpose is essential. The research progress of reference electrode used for several common environments is reviewed in this paper.
第16届世界地震工程大会有关报告研究进展综述
Summarization of the Related Research Progress of the 16th World Conference on Earthquake Engineering

王兰民,夏坤,董林,刘琨,王谦
- , 2017, DOI: 10.3969/j.issn.1000-0844.2017.02.0381
Abstract: 第16届世界地震工程大会于2017年1月9-13日在智利圣地亚哥市召开。大会主题为:“快速恢复-地震工程新挑战”。经中国地震局批准,在国际合作司的大力支持和指导下,自己有幸赴智利圣地亚哥市参加了第16届世界地震工程大会。本论文对会议概况做了简介,对其中3个大会特邀报告、2场辩论会和12个专题分会报告内容进行了综述,并与读者分享了我个人的体会和思考。论文综述涉及的3个大会特邀报告题目分别为“快速恢复:地震工程的下一个挑战”、“钢筋混凝土建筑物抗震设计中对快速恢复的探索——智利的实践”和“长持时地震动对土液化灾害的作用”;2场辩论会主题分别为“性态设计:是承诺还是陷阱?”和“抗震设防要求规定:概率性与确定性”;12个专题分会主题包括:结构倒塌概率的评估,改善发展中国家住房地震安全的非技术战略,近期破坏性地震(包括2015年尼泊尔地震)的现场调查与分析,深基础的土-结构相互作用,地面破坏与液化,地震引起的天然斜坡滑坡,岩土室内试验和现场试验,城市层面的地震危害性、危险性与地震风险管理,快速恢复,地震风险经济与保险,城市的未来:今天规划明天的地震风险,管理政策等。
The 16th World Conference on Earthquake Engineering was held in Santiago,Chile in January 9-13,2017.The theme of this conference is "Resilience,the new challenge in earthquake engineering".The author had the honor to participate in this Conference.This paper gives a brief introduction to the general program of the conference,which includes 3 invited lectures,2 debates and 12 parallel sessions of special topics,and lastly shares the author's personal experience and thinking.These 3 invited lectures titled "Resilience,the new challenge in earthquake engineering","The quest for resilience in seismic design of RC buildings:The Chilean practice","Effects of Long-Duration Motions on Soil Liquefaction Hazards".And these 2 debates about "Performance-Based Design:Promises and Pitfalls?","Prescription of Seismic Demands:Probabilistic vs.Deterministic".And those 12 parallel sessions include topics:Assessment of the probability of structural collapse,Non-technical strategy on improving housing seismic safety in developing countries,Field investigation and Analysis of recent destructive earthquakes including 2015 Nepal earthquakes,Soil-structure interaction of deep foundation,Ground failure liquefaction,Earthquake-induced landslides in natural slopes,Geotechnical laboratory test and in-situ test,Seismic hazard,risk and earthquake risk management at city level,Resilience,Earthquake risk economy and insurance,The future of the city:planning for future earthquake risk,Management policies,etc.
大跨径三塔缆索承重桥梁力学参数敏感度分析
周云岗,孙斌,肖汝诚
- , 2016, DOI: 10.11908/j.issn.0253-374x.2016.01.003
Abstract: 建立了主跨为1 400 m的三塔悬索桥、三塔斜拉桥和三塔斜拉悬吊协作体系3种桥型的有限元分析模型.考虑几何非线性效应,利用ANSYS参数化设计语言(APDL)编制了计算程序,分析了主梁的最大挠度、索塔塔顶最大位移及主缆抗滑移系数对主梁刚度、索塔刚度、塔梁约束刚度、矢跨比、中央扣等参数的敏感程度,并进一步确定了主梁刚度和索塔刚度合理取值范围.结果表明:主梁刚度对悬索桥影响较小;主塔刚度是3种桥型的核心参数;塔梁约束可改善3种桥型的力学性能;减小矢跨比或设置中央扣可提高结构刚度,但会降低主缆抗滑性能.
Finite element analysis models were established to analyze the variable characteristics of key structural parameters of three tower suspension bridge, three tower cable stayed bridge and three tower cable stayed suspension bridge. By using ANSYS parametric design language (APDL), a calculation program was prepared to analyze the maximum deflection of box girders, the maximum displacement of tower and the anti slide coefficient of main cable and their sensitivity to the stiffness of box girders and tower, the appropriate stiffness of longitudinal constrain between box girders and tower, rise span ratio and central buckle of main cable in consideration of the effect of geometric nonlinearity. Finally, the reasonable range of the stiffness of box girders and tower was determined. It is shown that the stiffness of box girders has little effect on suspension bridge. The stiffness of tower is the key factor that affects the structural characteristics of the bridges and the appropriate stiffness of longitudinal constrain is beneficial to the structural characteristics of the bridges. The reduction of rise span ratio or the setting of central buckle of main cable can improve the structural stiffness, but reduce the anti slide capability of main cable of cable supported bridge
大跨度混合梁斜拉桥耐久性失效风险评估
林晶,肖汝诚
- , 2015, DOI: 10.11908/j.issn.0253-374x.2015.03.007
Abstract: 为建立大跨度混合梁斜拉桥的耐久性失效风险评估体系,在分析耐久性和风险已有定义的基础上,从评估角度明确了耐久性失效风险的相关概念.考虑耐久性时间跨度大的特点,通过调研咨询识别了长期作用类型的风险因素,建立了大跨度混合梁斜拉桥耐久性失效风险源库.综合专家调查法、模糊综合评判法和层次分析法,研究了基于专家调查的模糊层次分析法用以评估耐久性失效风险.将重要度分析该概念引入耐久性失效风险评估,提出了耐久性失效风险重要度分析,该方法可以评价底层风险源对顶上风险事件的影响程度.以某长江大桥算例实践了上述风险评估体系,证明了其可行性.该体系可为大跨度混合梁斜拉桥的安全运营和预防性养护提供参考.
To construct a risk assessment system of durability failure for large span hybrid girder cable stayed bridge, new definitions related to durability failure risk were proposed from an assessment view based on the analysis of existing concepts of durability and risk. Considering the long time span of durability, risk factors which have long term effect were identified through investigation and consultation, thus the durability failure risk factor database of large span hybrid girder cable stayed bridge was built. Combining expert investigation method, fuzzy comprehensive evaluation method and analytic hierarchy process, the fussy analytic hierarchy process based on professor research was studied to assess the risk of durability failure. Introducing the analysis of importance rate to risk assessment of durability failure, durability failure risk importance analysis was proposed which can assess the impact on top risk event of bottom risk factors. Based on a certain Changjiang Bridge, the foregoing risk assessment system was practiced and the feasibility was proved, providing reference to security operation and preventive maintenance for large span hybrid girder
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