橋梁畢業(yè)設計外文翻譯---碳纖維復合材料修復混凝土橋梁結(jié)構(gòu)的詳述及應用

1、<p><b>　　外文資料</b></p><p>　　The Tenth East Asia-Pacific Conference on Structural Engineering and Construction</p><p>　　August 3-5, 2006, Bangkok, Thailand</p><p>　　S

2、tructural Rehabilitation of Concrete Bridges with CFRP Composites-Practical Details and Applications</p><p>　　Riyad S. ABOUTAHA1, and Nuttawat CHUTARAT2</p><p>　　ABSTRACT: Many old existing brid

3、ges are still active in the various highway transportation networks, carrying heavier and faster trucks, in all kinds of environments. Water, salt, and wind have caused damage to these old bridges, and scarcity of mainte

4、nance funds has aggravated their conditions. One attempt to restore the original condition; and to extend the service life of concrete bridges is by the use of carbon fiber reinforced polymer (CFRP) composites. There app

5、ear to be very limited guide</p><p>　　KEYWORDS: Concrete deterioration, corrosion of steel, bridge rehabilitation, CFRP composites.</p><p>　　1 Introduction</p><p>　　There are severa

6、l destructive external environmental factors that limit the service life of bridges. These factors include but not limited to chemical attacks, corrosion of reinforcing steel bars, carbonation of concrete, and chemical r

7、eaction of aggregate. If bridges were not well maintained, these factors may lead to a structural deficiency, which reduces the margin of safety, and may result in structural failure. In order to rehabilitate and/or stre

8、ngthen deteriorated existing bridges, thorou</p><p>　　1 Associate Professor, Syracuse University, U.S.A.</p><p>　　2 Lecturer, Sripatum University, Thailand.</p><p>　　One attempt to

9、restore the original condition, and to extend the service life of concrete bridges is by the use of carbon fiber reinforced polymer (CFRP) composites. </p><p>　　In North America, Europe and Japan, CFRP has b

10、een extensively investigated and applied. Several design guides have been developed for strengthening of concrete bridges with CFRP composites. However, there appear to be very limited guides on repair of deteriorated co

11、ncrete bridges with CFRP composites. This paper presents guidelines for repair of deteriorated concrete bridges, along with proper detailing. Evaluation, nondestructive testing, and rehabilitation of deteriorated concret

12、e bridges with</p><p>　　2 Deteriorated Concrete Bridges</p><p>　　Durability of bridges is of major concern. Increasing number of bridges are experiencing significant amounts of deterioration pri

13、or to reaching their design service life. This premature deterioration considered a problem in terms of the structural integrity and safety of the bridge. In addition, deterioration of a bridge has a considerable magnitu

14、de of costs associated with it. In many cases, the root of a deterioration problem is caused by corrosion of steel reinforcement in concrete structures</p><p>　　Figure1 Corrosion of the steel bars is leading

15、 to a structural deficiency</p><p>　　3 Non-destructive Testing of Deteriorated Concrete Bridge Piers</p><p>　　In order to design a successful retrofit system, the condition of the existing bridg

16、e should be thoroughly evaluated. Evaluation of existing bridge elements or systems involves review of the asbuilt drawings, as well as accurate estimate of the condition of the existing bridge, as shown in Figure2. Depe

17、nding on the purpose of evaluation, non-destructive tests may involve estimation of strength, salt contents, corrosion rates, alkalinity in concrete, etc.</p><p>　　Figure2 Visible concrete distress marked on

18、 an elevation of a concrete bridge pier</p><p>　　Although most of the non-destructive tests do not cause any damage to existing bridges, some NDT may cause minor local damage (e.g. drilled holes & coring

19、) that should be repaired right after the NDT. These tests are also referred to as partial destructive tests but fall under non-destructive testing.</p><p>　　In order to select the most appropriate non-destr

20、uctive test for a particular case, the purpose of the test should be identified. In general, there are three types of NDT to investigate: (1) strength, (2) other structural properties, and (3) quality and durability. The

21、 strength methods may include; compressive test (e.g. core test/rebound hammer/ ultrasonic pulse velocity), surface hardness test (e.g. rebound hammer), penetration test (e.g. Windsor probe), and pullout test (anchor tes

22、t).</p><p>　　Other structural test methods may include; concrete cover thickness (cover-meter), locating rebars (rebar locator), rebar size (some rebar locators/rebar data scan), concrete moisture (acquamete

23、r/moisture meter), cracking (visual test/impact echo/ultrasonic pulse velocity), delamination (hammer test/ ultrasonic pulse velocity/impact echo), flaws and internal cracking (ultrasonic pulse velocity/impact echo), dyn

24、amic modulus of elasticity (ultrasonic pulse velocity), Possion’s ratio (ultrasonic pu</p><p>　　Quality and durability test methods may include; rebar corrosion rate – field test, chloride profile field test

25、, rebar corrosion analysis, rebar resistivity test, alkali-silica reactivity field test, concrete alkalinity test (carbonation field test), concrete permeability (field test for permeability).</p><p>　　4 Non

26、-destructive Evaluation of Deteriorated Concrete Bridge Piers</p><p>　　The process of evaluating the structural condition of an existing concrete bridge consists of collecting information, e.g. drawings and

27、construction & inspection records, analyzing NDT data, and structural analysis of the bridge. The evaluation process can be summarized as follows: (1) Planning for the assessment, (2) Preliminary assessment, which in

28、volves examination of available documents, site inspection, materials assessment, and preliminary analysis, (3) Preliminary evaluation, this involve</p><p>　　If the information is insufficient to conduct eva

29、luation to a specific required level, then a detailed evaluation may be conducted following similar steps for the above-mentioned preliminary assessment, but in-depth assessment. Successful analytical evaluation of an ex

30、isting deteriorated concrete bridge should consider the actual condition of the bridge and level of deterioration of various elements. Factors, e.g. actual concrete strength, level of damage/deterioration, actual size of

31、 corroded r</p><p>　　5 Bridge Rehabilitation with CFRP Composites</p><p>　　Application of CFRP composite materials is becoming increasingly attractive to extend the service life of existing conc

32、rete bridges. The technology of strengthening existing bridges with externally bonded CFRP composites was developed primarily in Japan (FRP sheets), and Europe (laminates). The use of these materials for strengthening ex

33、isting concrete bridges started in the 1980s, first as a substitute to bonded steel plates, and then as a substitute for steel jackets for seismic retrofit of br</p><p>　　CFRP composites could be used to inc

34、rease the flexural and shear strength of bridge girders including pier cap beams, as shown in Figure3. In order to increase the ductility of CFRP strengthened concrete girders, the longitudinal CFRP composite sheets used

35、 for flexural strengthening should be anchored with transverse/diagonal CFRP anchors to prevent premature delamination of the longitudinal sheets due to localized debonding at the concrete surface-CFRP sheet interface. I

36、n order to prevent stres</p><p>　　Deterioration of concrete bridge members due to corrosion of steel bars usually leads in loss of steel section and delamination of concrete cover. As a result, such deterior

37、ation may lead to structural deficiency that requires immediate attention. Figure4 shows rehabilitation of structurally deficient concrete bridge pier using CFRP composites.</p><p>　　Figure3 Flexural and she

38、ar strengthening of concrete bridge pier with FRP composites</p><p>　　Figure4 Rehabilitation of deteriorated concrete bridge pier with CFRP composites</p><p>　　6 Summary and Conclusions</p>

39、;<p>　　Evaluation, non-destructive testing and rehabilitation of deteriorated concrete bridges were presented. Deterioration of concrete bridge components due to corrosion may lead to structural deficiencies, e.g.

40、 flexural and/or shear failures. Application of CFRP composite materials is becoming increasingly attractive solution to extend the service life of existing concrete bridges. CFRP composites could be utilized for flexura

41、l and shear strengthening, as well as for restoration of deteriorated conc</p><p>　　第十屆東亞太結(jié)構(gòu)工程設計與施工會議</p><p>　　2006年8月3-5號，曼谷，泰國</p><p>　　碳纖維復合材料修復混凝土橋梁結(jié)構(gòu)的詳述及應用</p><p>

42、　　Riyad S. ABOUTAHA1, and Nuttawat CHUTARAT2</p><p>　　摘要：在各式各樣的公路交通網(wǎng)絡中，許多現(xiàn)有的古老橋梁，在各種惡劣的環(huán)境下，如更重的荷載和更快的車輛等條件下，依然在被使用著。沖刷、腐蝕和風化對這些古老的橋梁已經(jīng)造成了破壞，而維修資金短缺更加劇了它們的損壞。一個利用碳纖維增強復合材料（CFRP）來延長混凝土橋梁的使用壽命的想法使橋梁恢復了原有的狀態(tài)。然而，

43、采用碳纖維復合材料修復受損混凝土橋梁的指導和規(guī)范還非常有限。在本文中對無損探傷、無損檢測和利用碳纖維復合材料修復已遭侵蝕的橋梁的方法進行了介紹。此設計對碳纖維增強混凝土橋的延性，及其應用后效果也進行了討論和介紹。</p><p>　　關(guān)鍵詞:混凝土腐蝕，鋼筋銹蝕，橋梁修復，碳纖維復合材料</p><p><b>　　1 簡介</b></p><p&

44、gt;　　在這里存在幾個有害的外部環(huán)境因素影響著橋梁的耐久性。這些因素包括但又不僅限于化學物的侵蝕，受力鋼筋的銹蝕，混凝土的碳化，化學物質(zhì)的聚合反應。如果橋梁維護不好，這些因素可能導致結(jié)構(gòu)的受損，如結(jié)構(gòu)邊緣不穩(wěn)定或結(jié)構(gòu)損毀。為了修復日漸惡化的現(xiàn)存橋梁，應當對其作徹底的評估。目的是通過大致檢測剩余耐久度和承載力，評定出所有現(xiàn)存橋梁的真實情況。</p><p>　　應用碳纖維復合材料可以恢復混凝土橋梁最初的狀況并延長

45、其使用年限。在北美、歐洲和日本，碳纖維復合材料應經(jīng)得到深入的研究和廣泛的應用。碳纖維復合材料的幾個設計指南也已經(jīng)被應用于強化混凝土橋梁。然而，采用碳纖維復合材料修復損壞的混凝土橋梁的指導和規(guī)范還非常有限。本文通過合適的例子給出了修復受損混凝土梁橋的準則，列出了評估、無損檢測、碳纖維復合材料復原受損混凝土橋梁。碳纖維復合材料的成功應用由于良好的細節(jié)設計，它主要考慮了集中力在碳纖維復合材料中依靠混凝土與碳纖維復合材料接觸面間的粘合劑轉(zhuǎn)移。此

46、設計對碳纖維增強混凝土橋的延性和反應的效果也進行了討論和介紹。</p><p>　　2 混凝土橋梁的損壞</p><p>　　橋梁的使用年限應該給予極大地關(guān)注。越來越多的橋梁在達到設計使用年限之前出現(xiàn)令人側(cè)目的破損。這些過早出現(xiàn)的損壞使得橋梁的結(jié)構(gòu)可靠性和安全性成為</p><p>　　1副教授，雪城大學，美國</p><p>　　2講師，斯

47、巴頓大學，泰國</p><p>　　了值得考慮的問題?？偟膩碚f，橋梁的損壞與考慮它的花費多少是緊密相關(guān)的。在很多情況下，損壞問題的根源是混凝土結(jié)構(gòu)中受力鋼筋的腐蝕。通常由混凝土保護層預防受力筋的腐蝕。然而，這些具有代表性的問題，如混凝土質(zhì)量差、不適當?shù)脑O計或施工和周圍惡劣的環(huán)境導致了鋼筋的腐蝕。如果不及時處理像鋼筋腐蝕這種耐久性問題，可能會引起受力不均問題，進而導致結(jié)構(gòu)失穩(wěn)，如圖1所示。</p>&

48、lt;p>　　圖1 鋼筋的銹蝕導致的結(jié)構(gòu)失穩(wěn)</p><p>　　3 損壞的混凝土梁橋墩柱的無損檢測</p><p>　　為了設計一個成功的新式系統(tǒng)，應該對橋梁現(xiàn)有的情況作徹底評估。評價現(xiàn)有橋梁的元素或體系需要翻看asbuilt圖紙，才能準確的評估出現(xiàn)有橋梁的狀況，如圖2所示。根據(jù)評估的目的，無損測試應該包括的內(nèi)容：強度的檢測，鹽度，腐蝕率，混凝土中堿含量等等。</p>

49、<p>　　雖然大多數(shù)的無損測試對現(xiàn)有橋梁不會造成任何損壞，一些無損檢測可能導致的輕微局部損傷（如鉆洞取芯），在無損檢測完畢后應予以修復。這些測試也被叫作部分破壞性測試,但屬于無損檢測。</p><p>　　圖2 混凝土橋墩可見缺陷正面圖</p><p>　　為了針對特殊情況選擇最合適的無損檢測，應該明確測試的目的。一般來說,有三種類型的無損檢測進行調(diào)查：（1）強度；（2）其他

50、結(jié)構(gòu)性質(zhì)；（3）質(zhì)量及耐久性。強度測試的方法可能包括：抗壓測試（如軸心抗壓、反彈測試儀、超聲波脈沖速度檢測）；表面硬度測試（如反彈儀測試）；貫入度試驗（如溫莎探針）；拉拔試驗（錨索抗拔試驗）。</p><p>　　其它結(jié)構(gòu)測試方法還包括：混凝土保護層厚度（保護層測量）；定位鋼筋位置（鋼筋定位器）；鋼筋尺寸（某些鋼筋定位器、鋼筋數(shù)據(jù)掃描儀）；混凝土的濕度（含水量測試儀、水分測定儀）；混凝土裂縫檢查（外觀鑒定、回音法

51、、超聲波脈沖回波速度檢查法）；混凝土分層剝離（錘擊試驗、超聲波脈沖回波速度檢查法、回音法）；缺陷和內(nèi)部開裂（超聲波脈沖回波速度檢查法、回音法）；動態(tài)彈性模量（超聲波脈沖回波速度檢查法）；泊松比（超聲波脈沖回波速度檢查法）；混凝土板或墻的厚度（超聲波脈沖回波速度檢查法）；碳纖維復合材料剝離（錘擊試驗、紅外線溫度記錄技術(shù)）；混凝土表面缺陷（外觀鑒定）。</p><p>　　質(zhì)量和耐久性試驗方法包括：鋼筋銹蝕率—現(xiàn)場試

52、驗，現(xiàn)場檢測剖面氯化物，驗定鋼筋銹蝕率，測試鋼筋電阻率，現(xiàn)場測定堿質(zhì)與粒料反應活性，混凝土堿度測定（碳化測定），混凝土的滲透性（現(xiàn)場滲透性試驗）。</p><p>　　4 損壞的混凝土梁橋墩柱的無損探傷</p><p>　　對一個現(xiàn)有混凝土橋梁結(jié)構(gòu)特征的評估由各種信息組成，如圖紙、構(gòu)筑物的檢查記錄，無損檢測的分析數(shù)據(jù)和橋梁的結(jié)構(gòu)分析。評估過程可以概括如下：（1）計劃評估；（2）預備評估，主

53、要包括現(xiàn)有文件檢查、實地檢查、材料檢驗和初步分析；（3）初步評估，主要有檢查階段，審查階段和完成階段。（4）有關(guān)成本影響的分析。</p><p>　　如果上述提供的信息，不足以用來進行高水平的評估。那么，我們做完上述的初步評估的步驟之后，可以再做一個詳細的、深入的評估。對于某個現(xiàn)存損壞的混凝土橋梁成功地分析評估應當考慮橋梁的實際情況及它的各部分的損壞程度。如果在適當?shù)囊欢螘r間內(nèi)很難完成如此詳細的分析，那么就可能需

54、要談及的依靠現(xiàn)場試驗得到的實際橋梁的評估。</p><p>　　5 碳纖維復合材料修復受損橋梁的應用</p><p>　　碳纖維復合材料的應用延長了既有混凝土橋梁的使用年限而變得越來越引人注目。在橋梁的外部粘結(jié)碳纖維復合材料加強現(xiàn)有橋梁的技術(shù)被廣泛應用在日本（纖維增強塑料板）和歐洲（多層纖維板）。在20世紀80年代，這些材料被應用于加強既有混凝土橋梁，最先是被用來替代鋼板，后來被用來替代鋼

55、套作為橋墩的耐震補強。碳纖維復合材料由纖維強化復合材料與合成樹脂基質(zhì)粘結(jié)在一起組成。纖維以其獨特的結(jié)構(gòu)性能使兩者良好復合。樹脂基質(zhì)支撐并保護著纖維，將外施荷載以剪應力的方式傳遞給纖維。大部分在建筑市場上能買到的碳纖維復合材料加固系統(tǒng)都是由單向纖維嵌套在樹脂基質(zhì)中構(gòu)成，最具代表性的是環(huán)氧樹脂。碳纖維的有限的極限應變可能會限制強化涂層中的元素的形變能力。然而，在交通荷載作用下，結(jié)構(gòu)在破壞之前且全局的形變在可接受的程度內(nèi)，碳纖維復合材料板與混

56、凝土基質(zhì)之間局部的脫膠是被允許的。</p><p>　　碳纖維復合材料可用于增加包括蓋梁在內(nèi)的橋主梁的抗彎及抗剪強度，如圖3所示。為了增加碳纖維復合材料加強的混凝土主梁的延性，防止由于混凝土基質(zhì)與碳纖維復合材料接觸面之間產(chǎn)生局部脫膠而造成的縱向板過早剝離，應將用于增強抗彎強度的縱向碳纖維復合材料板、橫向板及對角板互相錨固。為了防止在混凝土構(gòu)件的轉(zhuǎn)角處產(chǎn)生應力集中和碳纖維復合材料板過早斷裂，這些轉(zhuǎn)角應當是不小于50

57、mm（2.0英寸）半徑的圓角，如圖3所示。</p><p>　　圖3 碳纖維復合材料混凝土墩柱彎剪強度的加強</p><p>　　由于鋼筋的銹蝕而導致的鋼筋截面面積的損失和混凝土保護層的損壞是混凝土橋梁構(gòu)件損壞的根本原因。因此應該時刻注意像這樣可能會導致結(jié)構(gòu)失穩(wěn)的損壞。碳纖維復合材料對受損橋梁結(jié)構(gòu)的修復如下圖4所示。</p><p>　　圖4 碳纖維復合材料對受損橋

58、梁的修復</p><p><b>　　6 概要和結(jié)論</b></p><p>　　在上文中對測評橋梁、無損測試和對受損混凝土橋梁的修復進行了介紹。鋼筋的銹蝕可能會導致混凝土橋梁的構(gòu)件發(fā)生彎曲或者剪切破壞。由于碳纖維復合材料的應用延長了現(xiàn)有混凝土橋梁的使用年限，因此越來越多的人正在對它投入關(guān)注。碳纖維復合材料可以被應用于增加構(gòu)件的抗彎剪強度，也可以被用來修復混凝土橋梁的