橋梁工程畢業(yè)設(shè)計外文翻譯(共10頁)

1、精選優(yōu)質(zhì)文檔-傾情為你奉上Review of assessment and repair of fire-damaged RC highway bridgesAbstract：This paper presents a review of the progress of the research and engineering practice of assessment and repair of fire-damaged RC highway bridges，based on which existing and pressing problems of the evaluation me

2、thod are pointed outAt last，Prospect for the development of assessment and repair of fire-damaged highway bridges is also proposedKey words：fire damage；assessment；repair techniques；RC structure；bridge1 PrefaceFires can cause great structural damage to bridges and major disruption to highway operatio

3、nsThese incidents stem primarily from vehicle accident (often oil tanker) fires， bridges might also be damaged by fires in adjacent facilities and from other causesQuite a few of them，though rarely happened，lead to severe structural damage or collapse and casualtyOn June 2，2008，fire disaster broke o

4、ut under the 18th span of Nanjing Yangtze River Bridge and lasted for approximate 75min During the fires development and extinguishment，the structure experienced the sharp rise and fall in temperature causing severe damage to fire- stricken segmentsOn April 29，2007，a gasoline tanker overturned on th

5、e connector from Interstate 8O to Interstate 880 in CaliforniaThe intense heat from the subsequent fuel spill and fire weakened the stee1 underbelly of the elevated roadway ,collapsing approximately 165 feet of this elevated roadway onto a section of I880belowOn March 25，2004，Connecticut，United Stat

6、es，a tanker truck carrying fuel swerved to avoid a car and overturned，dumping 8000 gallons of home heating oil onto the Howard Avenue overpass The consequent towering inferno melted the bridge structure and caused the southbound lanes to sag several feetUndocumented number of bridge fires occurring

7、throughout the world each year cause varying degrees of disruption，repair actions，and maintenance costAlthough fires caused damage to the bridge structures ,some bridges continue to function after proper repair and retrofitStill in some situations they have to be repaired for the cause of traffic pr

8、essure even though supposed to be dismantled and reconstructedHowever ,in other cases， structures are severely damaged in the fire disaster and fail to function even after repair，or the costs of repair and retrofit overweigh their reconstruction costs overwhelmingly even if they are repairable， unde

9、r which situation reconstruction serves as a preferable optionTherefore insitu investigation and necessary tests and analyses should be conducted to make comprehensive assessment of the residual mechanical properties and working statuses after fire and to evaluate the degrees of damage of members an

10、d structures , in reference to which decisions are made to determine whether Fire damaged structures should be repaired or dismantled and reconstructedUrgent need from engineering practice highlighted the necessity to understand the susceptibility and severity of these incidents as wel1 as to review

11、 available information on mitigation strategies，damage assessments，and repair techniques.2 Progress in Research and Engineering Practice2.1 Processes of Assessment and Repair of Fire damaged Bridge StructureIn China and most countries in the world，most highway bridges are built in RC structureAnd th

12、e practice of the assessment and repair techniques of bridge structure after fire directly refer to that of RC structure，which，to date，domestic and foreign scholars have made great amount of research on，with their theories and practices being increasingly mature .As for the assessment and repair of

13、fire-damaged reinforced concrete structures， there are two mainstream assessment processes in worldCountries including United States，United Kingdom and Japan adopt the assessment process stipulated by The British Concrete Society .This process grates the severity of fire damage of concrete structure

14、 into four degrees according to the deflection， damage depth，cracking width, color， and loading capacity variation of fire-damaged structures and adopt four corresponding strategies (including demolish，strengthen after safety measures，strengthen. and strengthen in damaged segments) to deal with them

15、 accordingly In general，this process is a qualitative method and considered，however，not quantity enough.In Chinese Mainland and Taiwan ，the prevailing as assessment and repair process of fire damaged incorporates following steps：In comparison this process is more detailed(1)Conduct In-situ inspectio

16、ns，measurements，and tests including color observation，concrete observation，degree of rebar exposure observation， cracking measurement， deflection measurement， various destructive and nondestructive test methods as grounds for assessment of firedamaged structures In assessment of the post -fire mecha

17、nical properties of firedamaged structures，historical highest temperature and temperature distribution of structure during the fire serve as decisive factors The common methods to determine them incorporate petrographic analysis， ultrasonic method， Rebound method，Ignition Loss method，core test，and c

18、olor observation method(2)calculate to determine whether the fire-damaged structure can meet the demand of strength and deflection under working loads after fire using mechanical properties of rebar and concrete before and after fire based on the historical highest and temperature distribution of st

19、ructures obtained from step one There are two main methods to evaluate the post -fire performance of fire-damaged structures：FEM method and Revised Classic Method(3)On the basis of test and calculation results obtained from step two，take corresponding repair strategies and particular methods to stre

20、ngthen the fire-damaged structures.22 Repair TechniquesFor the repair of firedamaged bridge，proper repair methods should be taken according to the degree and range of the structures damageMeanwhile the safety and economy of the repair methods should be concerned with by avoiding destructing the orig

21、inal structure，preserving the valuable structural members， and minimizing unnecessary demolishment and reconstruction。Common repair techniques are listed as follows(1)Fire-damaged concrete ReplacementThe replacement of firedamaged concrete is the most common technique in damaged concrete repairIf th

22、e concrete structure is damaged only within the concrete cover，it is preferable to remove the firedamaged concrete from the structure making the rebar exposed and to make up the removed part by means of recasting or concrete spraying If the displacement of the structure exceeds the controlled value

23、or the embedded rebar is buckled，the damaged structure should be otherwise handled。(2)CFRP strengtheningCFRP materials have strong tensile strength and elasticity as well as excellent workability and durability and are widely applied in engineering practice in recent years CFRP materials are used to

24、 boost the loading capacity by adhering them to the edge of tensile region to replace the reinforced rebar .CFRP are especially suitable for the projects calling for boost of loading capacity while no extra weight is allowed(3)Structural member ReplacementFor slab bridges and girder bridges ,the dec

25、ks of the bridge are made of parallel girders or thick slabs .On condition that part of structural member is severely damaged in the fire so that its beyond repair or the repair cost over weigh a new one，it is preferable to replace thedamaged spans with new girders or slabsThough appears to be relat

26、ively high in cost, this method serves as reliable and effective way in engineering practice23 Case Study of Assessment and Repair Techniques of fire- damaged bridgesSome domestic and foreign scholars have conducted a series of studies on the inspection，assessment，and repair techniques of fire damag

27、ed bridges in the engineering practice by different assessment standards and processes on the casebycase basis using a variety of field andlaboratory evaluation methods， including both destructive and nondestructive testingLiterature employed visual inspection and material testing including compress

28、ive strength testing and petrographic analysis(paste depth， micro cracking，color change)on a fire-damaged bridge，based on which 1oad rating analysis was performed using reduced girder and deck sectionsLiterature made qualitative safety evaluation on two fire-damaged bridge structures using the rebou

29、nd method，core tests，carbonization depth measurement， concrete cover measurement，deflection measurement，and appearance observation Literature use the combination of ultrasonic method and rebound method to determine the historical highest temperature of structures in fire，based on which stiffness and

30、 strength of two fire damaged structures are determined to make safety evaluations on them And then CFRP and structural adhensive are used to strengthen the firedamaged segments respectivelyLiterature made a safety evaluation on a prestressed reinforced concrete slab bridge， the firedirectlystricken

31、 segments of which are severely spalled and carbonized with embedded rebars and prestressed strands exposed Its rubber isolators were also highly carbonizedThe researcher took the core tests and inferred that local segments of the slabs were severely damaged and the prestress had been lostMeanwhile，

32、the researcher conducted a series of dynamic tests on the damaged bridge and presumed that the variation of the comprehensive performance of the bridge structure after fire was insignificant in reference to the results of the dynamic tests . The researcher proposed to replace the severely damaged sl

33、abs from the perspective of durability and safetyLiterature made the damage assessment and repair work on a fire- damaged T- shaped prestressed beam bridge The fire disaster was derived from the leakage of a oil tanker and then the burning oil was spread to the underbelly of the bridge Several bound

34、ary and secondary boundary girders are consequently damaged in the fire. Judging by the fire duration，color change，and damage depth，the researcher concluded that the fire-damaged girders fell the category of severely-damaged structures and cannot be repaired for the prestress loss and material degra

35、dation Therefore five spans of boundary and secondary boundary girders are dismantled and reconstructedLiterature：1 Martha Davis，PE ，Paul Tremel，PE，Alex PedregoBill williams Bridge Fire AssessmentJStructure Magazine，2008，：3O一322 FENG Zhi-nan，CHEN AipingInspection and Assessment of an Expressway Unde

36、rpass Bridge After Fire DamageJWorld Bridges，2009，(2)：65673 LI Yi，XIANG Yiqiang，WANG JianjiangDamage Detection and Safety Assessment on Bridge Structure after Fire AccidentJChina MunicipalEngineering，2006，(5)：26274 LIU Qiwei，WANG Feng，XU Kaishun，CHEN Xiao qiangDetection Evaluation and Repairing of F

37、ire Damaged BridgeJJournal of Highway and Transportation Research and Development，2005，22 (2)：71745 XI YongInspection and Evaluation of Fire Damaged BridgesJWorld Bridges，2007，(4)：62656 SUN Dasong，MIAO Changqing，LI Zhijun Examination and Evaluation of a Prestressed Concrete Slab Bridge after FireJMu

38、nicipal Engineering Technology，2007，25(3)：2462487 Zheng Jiguang，W ang Xing，Liu ZhongguAnalysis of Unforeseen Co nflagration Injury of Prestressed Concret Bridge StructureJNorthern Communieations，2007，(12)：54 57 對火災(zāi)后鋼筋混凝土公路橋梁的評估和修復(fù)摘要:本文綜述了對火災(zāi)后鋼筋混凝土公路橋梁的研究進(jìn)展,工程實踐評估以及修復(fù),并在此基礎(chǔ)上指出了現(xiàn)有的評估方法以及急需解決的問題.除此之外,還

39、對火災(zāi)后的公路橋梁的評估和修復(fù)提出了展望.關(guān)鍵字:火災(zāi)損害；評估；修復(fù)技術(shù)；鋼筋混凝土結(jié)構(gòu)；橋梁。1. 前言火災(zāi)能夠?qū)蛄航Y(jié)構(gòu)造成重大損害，并影響公路的正常使用功能。起因主要源自車輛交通事故（通常是指油罐車）造成的火災(zāi)，周邊設(shè)施著火或者其他因素，都可能使橋梁結(jié)構(gòu)發(fā)生損壞。盡管許多因素鮮有發(fā)生，但一旦產(chǎn)生就會造成橋梁嚴(yán)重?fù)p壞并帶來人員傷亡。2008年6月2日，18跨度的南京長江大橋發(fā)生了火災(zāi)，火災(zāi)持續(xù)了將近75分鐘。伴隨著大火持續(xù)燃燒和最終被撲滅，橋梁結(jié)構(gòu)承受了急劇的溫差變化，并給火災(zāi)影響到的橋段帶來了嚴(yán)重的損壞。2007 年 4月29日，一輛油罐車在加利福尼亞州80號公路與880號公路交匯處發(fā)

40、生側(cè)翻，隨后燃油泄漏，大火產(chǎn)生的強(qiáng)熱削弱了高架橋下不鋼材的強(qiáng)度，最終高約165英尺高架路橋I-880段發(fā)生倒塌。2004年3月25日，美國Connecticut州，一輛攜帶燃油的油罐車為了躲開與另外一輛車的相撞，左右轉(zhuǎn)彎時發(fā)生傾倒，8000加侖的家庭供暖燃油被傾倒在Howard Avenue 立交橋，隨后漫天火海融化了橋梁結(jié)構(gòu)，導(dǎo)致立交橋南行線降低了幾英尺。世界各地還有許多未公布的橋梁火災(zāi)事故，都給橋梁造成了不同程度的損壞，增加了修復(fù)和維護(hù)成本。雖然火災(zāi)給橋梁結(jié)構(gòu)造成了損害，但經(jīng)過適當(dāng)?shù)木S修和翻新，一些橋梁仍能繼續(xù)使用。但在某些情況下，即使有些橋梁該被拆除重建，但迫于交通壓力，他們不得不在被維

41、修之后就投入使用。然而，在某些情況下，橋梁在火災(zāi)中損壞嚴(yán)重，即使被修復(fù)也無法正常使用。有時橋梁修復(fù)翻新的費用壓倒性地超過了重建的費用，在這種情況下，重建是一個較好的選擇。因此，應(yīng)該對火災(zāi)后橋梁殘余的力學(xué)性能和工作狀態(tài)進(jìn)行深入現(xiàn)場調(diào)查，做必要的檢測分析，以準(zhǔn)確檢測出結(jié)構(gòu)構(gòu)件的破壞程度，之后來判定是該修復(fù)被損毀的橋梁，還是將其拆了重建。實際工程的迫切需求，強(qiáng)調(diào)了很有必要去了解橋梁對事故發(fā)生的敏感性，嚴(yán)重性，以及重新審查減災(zāi)戰(zhàn)略，損害評定和修復(fù)方法的相關(guān)信息。2. 研究與工程實踐的進(jìn)展2.1 橋梁結(jié)構(gòu)受火災(zāi)損壞的評估以及修復(fù)進(jìn)展在世界上許多國家包括中國,大部分的公路橋是鋼筋混凝土結(jié)構(gòu).實際當(dāng)中我們會

42、直接參照混凝土結(jié)構(gòu)來對遭受火災(zāi)之后的橋梁進(jìn)行評估和修復(fù),如此一來,到目前為止,國內(nèi)外的學(xué)者經(jīng)過做了大量研究,這些理論和實踐正日益成熟.至于對火災(zāi)后的橋梁結(jié)構(gòu)進(jìn)行評估和修復(fù),世界上有兩種主流的評估流程.包括美國,英國和日本在內(nèi)的許多國家都采用了由英國土木工程協(xié)會制定的評估流程.參照偏斜的大小,損傷深度,裂縫寬,顏色以及損毀結(jié)構(gòu)承載力的變化,評估流程將混凝土結(jié)構(gòu)受火災(zāi)損壞程度劃分為四個等級,并采取相應(yīng)措施(包括拆除,安全測量加固,加固受損段)對其進(jìn)行處理.一般來說，這是一個定性的流程，而不單單定量就足夠了。中國大陸和臺灣，現(xiàn)行的評估和修復(fù)過程采用如下步驟：經(jīng)比較這種流程更詳細(xì)。（1）進(jìn)行現(xiàn)場調(diào)查，

43、測量。顏色觀察，具體觀測鋼筋暴露程度，開裂深度測量，撓度檢測以及各種破壞性和非破壞性的測試方法，是對火災(zāi)損壞結(jié)構(gòu)的評估依據(jù)。對火災(zāi)損毀的結(jié)構(gòu)進(jìn)行災(zāi)后力學(xué)性能分析，并對火災(zāi)過程中，結(jié)構(gòu)所達(dá)到的最高溫度以及溫度分布進(jìn)行分析。常用的方法有巖相分析，超聲波法，核心測試和顏色觀察。（2）依據(jù)火災(zāi)之后工作荷載下的鋼筋和混凝土力學(xué)性能，按照步驟一中火災(zāi)前后結(jié)構(gòu)所承受的最高溫以及溫度分布分析，通過計算來確定災(zāi)后結(jié)構(gòu)是否滿足強(qiáng)度和撓度的要求。有兩種主流的方法來判定結(jié)構(gòu)遭受大火損壞之后其工作性能：FEM法和傳統(tǒng)修復(fù)法。（3）依據(jù)步驟二的結(jié)果統(tǒng)計和測試，采取相應(yīng)的修復(fù)方案以及特定的方法，來加固受火災(zāi)損毀的結(jié)構(gòu)。2.2 修復(fù)技術(shù)修復(fù)火災(zāi)損毀的橋梁，應(yīng)依據(jù)結(jié)構(gòu)損壞的程度和范圍來采取恰當(dāng)?shù)男迯?fù)方案。同時應(yīng)該關(guān)注修復(fù)方法的安全性和經(jīng)濟(jì)型，盡量避免破壞原有結(jié)構(gòu)，保留有價值的構(gòu)件，減少不必要的拆遷和重建。常規(guī)修復(fù)技術(shù)如下。（1）更換火災(zāi)損壞的混凝土用新混凝土代替火災(zāi)損壞的混凝土，是最常用的修復(fù)技術(shù)。如果僅僅是結(jié)構(gòu)