橋梁畢業(yè)設(shè)計(jì)外文翻譯---平衡懸臂施工混凝土橋撓度和溫度的自動(dòng)監(jiān)測

1、<p>　　3000英文單詞，16500英文字符，中文4400字</p><p>　　出處：Burdet O. Automatic Deflection and Temperature Monitoring of a Balanced Cantilever Concrete Bridge[C]// 5th International Conference of Short and Medium Span

2、 Bridges, 1998:211-213.</p><p><b>　　附錄一 英文翻譯</b></p><p><b>　　原文</b></p><p>　　AUTOMATIC DEFLECTION AND TEMPERATURE MONITORING OF</p><p>　　A BALA

3、NCED CANTILEVER CONCRETE BRIDGE by Olivier BURDET, Ph.D.</p><p>　　Swiss Federal Institute of Technology, Lausanne, Switz

4、erland</p><p>　　Institute of Reinforced and Prestressed Concrete</p><p><b>　　SUMMARY </b></p><p>　　There is a need for reliable monitoring systems to follow the evolutio

5、n of the behavior of structures over time.</p><p>　　Deflections and rotations are values that reflect the overall structure behavior. This paper presents an innovative approach to the measurement of long-ter

6、m deformations of bridges by use of inclinometers. High precision electronic inclinometers can be used to follow effectively long-term rotations without disruption of the traffic. In addition to their accuracy, these ins

7、truments have proven to be sufficiently stable over time and reliable for field conditions.</p><p>　　The Mentue bridges are twin 565 m long box-girder post-tensioned concrete highway bridges under constructi

8、on in Switzerland. The bridges are built by the balanced cantilever method over a deep valley. The piers are 100 m high and the main span is 150 m. A centralized data acquisition system was installed in one bridge during

9、 its construction in 1997. Every minute, the system records the rotation and temperature at a number of measuring points. The simultaneous measurement of rotations and concre</p><p>　　Preliminary results sho

10、w that the system performs reliably and that the accuracy of the sensors is excellent.</p><p>　　Comparison of the evolution of rotations and temperature indicate that the structure responds to changes in air

11、 temperature rather quickly.</p><p>　　BACKGROUND </p><p>　　All over the world, the number of structures in service keeps increasing. With the development of traffic and the increased dependence

12、on reliable transportation, it is becoming more and more necessary to foresee and anticipate the deterioration of structures. In particular, for structures that are part of major transportation systems, rehabilitation wo

13、rks need to be carefully planned in order to minimize disruptions of traffic. Automatic monitoring of structures is thus rapidly developing.</p><p>　　Long-term monitoring of bridges is an important part of t

14、his overall effort to attempt to minimize both the impact and the cost of maintenance and rehabilitation work of major structures. By knowing the rate of deterioration of a given structure, the engineer is able to antici

15、pate and adequately define the timing of required interventions. Conversely, interventions can be delayed until the condition of the structure requires them, without reducing the overall safety of the structure.</p>

16、;<p>　　The paper presents an innovative approach to the measurement of long-term bridge deformations. The use of high precision inclinometers permits an effective, accurate and unobtrusive following of the long-te

17、rm rotations. The measurements can be performed under traffic conditions. Simultaneous measurement of the temperature at several locations gives a clear idea of the movements induced by thermal conditions and those induc

18、ed by creep and shrinkage. The system presented is operational since Augus</p><p>　　2. LONG-TERM MONITORING OF BRIDGES </p><p>　　As part of its research and service activities within the Swiss

19、Federal Institute of Technology in Lausanne (EPFL), IBAP - Reinforced and Prestressed Concrete has been involved in the monitoring of long-time deformations of bridges and other structures for over twenty-five years [1,

20、2, 3, 4]. In the past, IBAP has developed a system for the measurement of long-term deformations using hydrostatic leveling [5, 6]. This system has been in successful service in ten bridges in Switzerland for approxi<

21、/p><p>　　Occasional continuous measurements over periods of 24 hours have shown that the amplitude of daily movements is significant, usually amounting to several millimeters over a couple of hours. This is exe

22、mplified in figure 1, where measurements of the twin Lutrive bridges, taken over a period of several years before and after they were strengthened by post-tensioning, are shown along with measurements performed over a pe

23、riod of 24 hours. The scatter observed in the data is primarily caused by therm</p><p>　　Instantaneous measurements, as those made by hydrostatic leveling, are not necessarily representative of the mean posi

24、tion of the bridge. This occurs because the position of the bridge at the time of the measurement is influenced by the temperature history over the past several hours and days. Even if every care was taken to perform the

25、 measurements early in the morning and at the same period every year, it took a relatively long time before it was realized that the retrofit performed on the Lut</p><p>　　Figure 1: Long-term deflections of

26、the Lutrive bridges, compared to deflections measured in a 24-hour period Automatic data acquisition, allowing frequent measurements to be performed at an acceptable cost, is thus highly desirable. A study of possible so

27、lutions including laser-based leveling, fiber optics sensors and GPS-positioning was performed, with the conclusion that, provided that their long-term stability can be demonstrated, current types of electronic inclinome

28、ters are suitable for aut</p><p>　　3. MENTUE BRIDGES </p><p>　　The Mentue bridges are twin box-girder bridges that will carry the future A1 motorway from Lausanne to Bern. Each bridge, similar

29、in design, has an overall length of approximately 565 m, and a width of 13.46 m, designed to carry two lanes of traffic and an emergency lane. The bridges cross a deep valley with steep sides (fig. 2). The balanced canti

30、lever design results from a bridge competition. The 100 m high concrete piers were built using climbing formwork, after which the construction of the </p><p>　　4. INCLINOMETERS </p><p>　　Startin

31、g in 1995, IBAP initiated a research project with the goal of investigating the feasibility of a measurement system using inclinometers. Preliminary results indicated that inclinometers offer several advantages for the a

32、utomatic monitoring of structures. Table 1 summarizes the main properties of the inclinometers selected for this study.</p><p>　　One interesting property of measuring a structure’s rotations, is that, for a

33、given ratio of maximum deflection to span length, the maximum rotation is essentially independent from its static system [8]. Since maximal allowable values of about 1/1,000 for long-term deflections under permanent load

34、s are generally accepted values worldwide, developments made for box-girder bridges with long spans, as is the case for this research, are applicable to other bridges, for instance bridges with shorter </p><p&

35、gt;　　The selected inclinometers are of type Wyler Zerotronic ± 1° [9]. Their accuracy is 1 microradian (μrad), which corresponds to a rotation of one millimeter per kilometer, a very small value. For an interme

36、diate span of a continuous beam with a constant depth, a mid-span deflection of 1/20,000 would induce a maximum rotation of about 150 μrad, or 0.15 milliradians (mrad).</p><p>　　One potential problem with el

37、ectronic instruments is that their measurements may drift over time. To quantify and control this problem, a mechanical device was designed allowing the inclinometers to be precisely rotated of 180° in an horizontal

38、 plane (fig. 4). The drift of each inclinometer can be very simply obtained by comparing the values obtained in the initial and rotated position with previously obtained values. So far, it has been observed that the type

39、 of inclinometer used in this projec</p><p>　　5. INSTRUMENTATION OF THE MENTUE BRIDGES </p><p>　　Because a number of bridges built by the balanced cantilever method have shown an unsatisfactory

40、 behavior in service [2, 7,10], it was decided to carefully monitor the evolution of the deformations of the Mentue bridges. These bridges were designed taking into consideration recent recommendations for the choice of

41、the amount of posttensioning [7,10,13]. Monitoring starting during the construction in 1997 and will be pursued after the bridges are opened to traffic in 2001. Deflection monitoring i</p><p>　　The automatic

42、 monitoring system is driven by a data acquisition program that gathers and stores the data. This system is able to control various types of sensors simultaneously, at the present time inclinometers and thermal sensors.

43、The computer program driving all the instrumentation offers a flexible framework, allowing the later addition of new sensors or data acquisition systems. The use of the development environment LabView [14] allowed to le

44、verage the large user base in the field of labo</p><p>　　6. SENSORS </p><p>　　Figure 5(a) shows the location of the inclinometers in the main span of the North bridge. The sensors are placed at

45、the axis of the supports (①and⑤), at 1/4 and 3/4 (③and④) of the span and at 1/8 of the span for ②. In the cross section, the sensors are located on the North web, at a height corresponding to the center of gravity of the

46、 section (fig.5a). The sensors are all connected by a single RS-485 cable to the central data acquisition system located in the vicinity of inclinometer ①. Monitori</p><p>　　The deflected shape will be deter

47、mined by integrating the measured rotations along the length of the bridge (fig.5b). Although this integration is in principle straightforward, it has been shown [8, 16] that the type of loading and possible measurement

48、errors need to be carefully taken into account.</p><p>　　Thermal sensors were embedded in concrete so that temperature effects could be taken into account for the adjustment of the geometry of the formwork f

49、or subsequent casts. Figure 6 shows the layout of thermal sensors in the main span. The measurement sections are located at the same sections than the inclinometers (fig. 5). All sensors were placed in the formwork befor

50、e concreting and were operational as soon as the formwork was removed, which was required for the needs of the construction. In ea</p><p>　　7. RESULTS </p><p>　　Figure 7 shows the results of in

51、clinometry measurements performed from the end of September to the third week of November 1997. All inclinometers performed well during that period. Occasional interruptions of measurement, as observed for example in ear

52、ly October are due to interruption of power to the system during construction operations. The overall symmetry of results from inclinometersseem to indicate that the instruments drift is not significant for that time per

53、iod. The maximum amplitude o</p><p>　　Figure 8 shows a detail of the measurements made in November, while figure.9 shows temperature measurements at the top and bottom of the section at mid-span made during

54、that same period. It is clear that the measured deflections correspond to changes in the temperature. The temperature at the bottom of the section follows closely variations of the air temperature (measured in the shade

55、near the north web of the girder). On the other hand, the temperature at the top of the cross section is less s</p><p>　　8. FUTURE DEVELOPMENTS </p><p>　　Future developments will include algorit

56、hms to reconstruct deflections from measured rotations. To enhance the accuracy of the reconstruction of deflections, a 3D finite element model of the entire structure is in preparation [15]. This model will be used to i

57、dentify the influence on rotations of various phenomena, such as creep of the piers and girder, differential settlements, horizontal and vertical temperature gradients or traffic loads.</p><p>　　Much work wi

58、ll be devoted to the interpretation of the data gathered in the Mentue bridge. The final part of the research project work will focus on two aspects: understanding the very complex behavior of the structure, and determin

59、ing the most important parameters, to allow a simple and effective monitoring of the bridges deflections.</p><p>　　Finally, the research report will propose guidelines for determination of deflections from m

60、easured rotations and practical recommendations for the implementation of measurement systems using inclinometers. It is expected that within the coming year new sites will be equipped with inclinometers. Experiences mad

61、e by using inclinometers to measure deflections during loading tests [16, 17] have shown that the method is very flexible and competitive with other high-tech methods.</p><p>　　As an extension to the current

62、 research project, an innovative system for the measurement of bridge joint movement is being developed. This system integrates easily with the existing monitoring system, because it also uses inclinometers, although fro

63、m a slightly different type.</p><p>　　9. CONCLUSIONS </p><p>　　An innovative measurement system for deformations of structures using high precision inclinometers has been developed. This system

64、 combines a high accuracy with a relatively simple implementation. Preliminary results are very encouraging and indicate that the use of inclinometers to monitor bridge deformations is a feasible and offers advantages. T

65、he system is reliable, does not obstruct construction work or traffic and is very easily installed. Simultaneous temperature measurements have confirm</p><p>　　10. REFERENCES </p><p>　　[1] ANDRE

66、Y D., Maintenance des ouvrages d’art: méthodologie de surveillance, PhD Dissertation Nr 679, EPFL, Lausanne, Switzerland, 1987. </p><p>　　[2] BURDET O., Load Testing and Monitoring of Swiss Bridges, CEB

67、 Information Bulletin Nr 219, Safety and Performance Concepts, Lausanne, Switzerland, 1993.</p><p>　　[3] BURDET O., Critères pour le choix de la quantité de précontrainte découlant de l.o

68、bservation de ponts existants, CUST-COS 96, Clermont-Ferrand, France, 1996.</p><p>　　[4] HASSAN M., BURDET O., FAVRE R., Combination of Ultrasonic Measurements and Load Tests in Bridge Evaluation, 5th Intern

69、ational Conference on Structural Faults and Repair, Edinburgh, Scotland, UK, 1993.</p><p>　　[5] FAVRE R., CHARIF H., MARKEY I., Observation à long terme de la déformation des ponts, Mandat de Reche

70、rche de l’OFR 86/88, Final Report, EPFL, Lausanne, Switzerland, 1990.</p><p>　　[6] FAVRE R., MARKEY I., Long-term Monitoring of Bridge Deformation, NATO Research Workshop, Bridge Evaluation, Repair and Rehab

71、ilitation, NATO ASI series E: vol. 187, pp. 85-100, Baltimore, USA, 1990.</p><p>　　[7] FAVRE R., BURDET O. et al., Enseignements tirés d’essais de charge et d’observations à long terme pour l’é

72、;valuation des ponts et le choix de la précontrainte, OFR Report, 83/90, Zürich, Switzerland, 1995. </p><p>　　[8] DAVERIO R., Mesures des déformations des ponts par un système d’i

73、nclinométrie, Rapport de maîtrise EPFL-IBAP, Lausanne, Switzerland, 1995.</p><p>　　[9] WYLER AG., Technical specifications for Zerotronic Inclinometers, Winterthur, Switzerland, 1996.</p>&l

74、t;p>　　[10] FAVRE R., MARKEY I., Generalization of the Load Balancing Method, 12th FIP Congress, Prestressed Concrete in Switzerland, pp. 32-37, Washington, USA, 1994.</p><p>　　[11] FAVRE R., BURDET O., CH

75、ARIF H., Critères pour le choix d’une précontrainte: application au cas d’un renforcement, "Colloque International Gestion des Ouvrages d’Art: Quelle Stratégie pour Maintenir et Adapter le Patrimoine,

76、 pp. 197-208, Paris, France, 1994.</p><p>　　[12] FAVRE R., BURDET O., Wahl einer geeigneten Vorspannung, Beton- und Stahlbetonbau, Beton- und Stahlbetonbau, 92/3, 67, Germany, 1997.</p><p>　　[13

77、] FAVRE R., BURDET O., Choix d’une quantité appropriée de précontrainte, SIA D0 129, Zürich, Switzerland, 1996.</p><p>　　[14] NATIONAL INSTRUMENTS, LabView User.s Manual, Austin, USA, 199

78、6.</p><p>　　[15] BOUBERGUIG A., ROSSIER S., FAVRE R. et al, Calcul non linéaire du béton armé et précontraint, Revue Français du Génie Civil, vol. 1 n° 3, Hermes, Paris, Fr

79、ance, 1997.</p><p>　　[16] FEST E., Système de mesure par inclinométrie: développement d’un algorithme de calcul des flèches, Mémoire de maîtrise de DEA, Lausanne / Paris, Switze

80、rland / France, 1997.</p><p>　　[17] PERREGAUX N. et al., Vertical Displacement of Bridges using the SOFO System: a Fiber Optic Monitoring Method for Structures, 12th ASCE Engineering Mechanics Conference, Sa

81、n Diego, USA, to be published,1998.</p><p><b>　　譯文</b></p><p>　　平衡懸臂施工混凝土橋撓度和溫度的自動(dòng)監(jiān)測                &

82、#160;                         作者Olivier BURDET博士         

83、                             瑞士聯(lián)邦理工學(xué)院，洛桑，瑞士      &#

84、160;                                 鋼筋和預(yù)應(yīng)力混凝土研究所</p

85、><p>　　概要：我們想要跟蹤結(jié)構(gòu)行為隨時(shí)間的演化，需要一種可靠的監(jiān)測系統(tǒng)。 撓度和旋轉(zhuǎn)兩個(gè)參數(shù)反映了結(jié)構(gòu)的整體行為。本文提出了一種測量橋梁長期變形的創(chuàng)新方法，即，使用傾角儀。高精密電子傾角儀可以有效地追蹤橋梁的長期旋轉(zhuǎn)而不需要中斷交通。除了準(zhǔn)確，這些儀器已被證明隨著時(shí)間的推移是足夠穩(wěn)定，野外條下也非常可靠。 Mentue橋，長565m，雙箱雙室梁，后張法預(yù)應(yīng)力混凝土公路橋梁，修建于瑞士。該橋由平衡懸臂法

86、修建于一條深谷之上。墩高100m，主跨為150m。一個(gè)集中的數(shù)據(jù)采集系統(tǒng)于1997年修建該橋時(shí)安裝在一梁上。每一分鐘，系統(tǒng)記錄了很多測量點(diǎn)的旋轉(zhuǎn)量和溫度值。在多個(gè)地點(diǎn)同時(shí)測量出的旋轉(zhuǎn)量和混凝土溫度給出了熱條件引起的變動(dòng)的清晰概念。該系統(tǒng)將與一水平裝置結(jié)合使用，用以跟蹤橋梁的長期行為。</p><p>　　初步結(jié)果表明該系統(tǒng)運(yùn)行可靠，并且傳感器的準(zhǔn)確性非常優(yōu)秀。 對旋轉(zhuǎn)和溫度的演變比較表明，結(jié)構(gòu)對氣溫變化

87、的反應(yīng)相當(dāng)快。 1. 背景 遍布世界，服役結(jié)構(gòu)的數(shù)量在不斷增加。隨著交通的發(fā)展，我們?nèi)找嬉蕾囉诳煽康慕煌ㄟ\(yùn)輸，越來越有必要去預(yù)見和預(yù)測結(jié)構(gòu)的惡化。特別是，對于主要運(yùn)輸系統(tǒng)的那部分結(jié)構(gòu)，修復(fù)工程需要認(rèn)真規(guī)劃，以盡量減少交通中斷。結(jié)構(gòu)自動(dòng)監(jiān)測儀器從而迅速發(fā)展。 長期橋梁監(jiān)測是這一全面努力的重要組成部分，以嘗試減少對主要結(jié)構(gòu)的影響和維修工程的費(fèi)用。通過了解某一特定結(jié)構(gòu)的惡化速度，工程師能夠預(yù)見并充分界定所要求的處理措施的

88、時(shí)機(jī)。相反，不降低結(jié)構(gòu)的整體安全性，處理可以推遲到結(jié)構(gòu)需要相應(yīng)措施的時(shí)候。 本文提出了一種檢測橋梁長期變形的創(chuàng)新方法。高精度傾角儀的使用允許我們可以對長期旋轉(zhuǎn)進(jìn)行有效、準(zhǔn)確和無障礙跟蹤。該測量設(shè)備可以在正常交通狀況下運(yùn)行。同一時(shí)間測量的、多個(gè)地點(diǎn)的溫度給出了一個(gè)由熱、蠕變和收縮導(dǎo)致的變形的清晰概念。提出該系統(tǒng)的可行性是1997年8月開始運(yùn)營的修建于瑞士的Mentue橋。該橋主跨150m，墩高100m。 2. 橋梁的長期監(jiān)測

89、 作</p><p>　　瞬時(shí)測量，如水準(zhǔn)測量得出的結(jié)果，不一定代表了該橋的平均位置。這是因?yàn)樵跇蛄簻y量時(shí)的位置是受過去幾個(gè)小時(shí)、幾天氣溫的溫度歷史影響。即使周全的考慮影響監(jiān)測測量結(jié)果的因素并且在每年的同一時(shí)期進(jìn)行測量，也需要相對較長的時(shí)間，我們才能弄清楚Lutrive橋在1988年進(jìn)行改造時(shí)額外橋梁后張[3,7,11]有沒有產(chǎn)生與兩者相同的影響。 圖1：Lutrive橋的長期撓度，與24小時(shí)內(nèi)撓度自動(dòng)采

90、集的數(shù)據(jù)，使得我們可以在一個(gè)可接受的成本上進(jìn)行方便地測量，因此非常可取。一個(gè)可能的解決方案研究，進(jìn)行了包括基于激光水準(zhǔn)，光纖傳感器和GPS定位，得出的結(jié)論是，只要可以確保它們的長期穩(wěn)定性，當(dāng)前類型的電子傾角儀，都適合于自動(dòng)測量現(xiàn)有橋梁的旋轉(zhuǎn)量[8]。 </p><p>　　3. MENTUE道橋 </p><p>　　Mentue橋是單箱雙室箱梁橋，將銜接從洛桑到伯爾尼的未來A1高速公路。

91、每片梁設(shè)計(jì)類似，擁有約565m的,整體長度和13.46m的寬度，設(shè)計(jì)承載兩行車線和一個(gè)應(yīng)急車道。橋梁跨越一兩側(cè)有陡峭山坡的深谷（圖2）。平衡懸臂橋梁施工設(shè)計(jì)是與另一橋梁方案比選的結(jié)果。100m高的混凝土橋墩用爬模施工方法完成后，平衡懸臂施工啟動(dòng)（圖3） 。</p><p><b>　　4. 傾角儀 </b></p><p>　　從1995年開始，IBAP發(fā)起了一個(gè)

92、研究項(xiàng)目，目的是調(diào)查利用傾角儀的測量系統(tǒng)的可行性。初步結(jié)果表明，傾角儀為結(jié)構(gòu)提供自動(dòng)監(jiān)測提供了些許優(yōu)點(diǎn)。表1總結(jié)了本研究選擇的</p><p>　　傾角儀的主要特性。 衡量結(jié)構(gòu)轉(zhuǎn)動(dòng)的有趣屬性是，對于一個(gè)給定的最大撓度跨度比，最大旋轉(zhuǎn)基本上是獨(dú)立于它的靜態(tài)系統(tǒng)[8]。由于在永久荷載下，最大允許值約1 / 1000的長期撓度已經(jīng)被全世界普遍接受，就像這項(xiàng)研究中大跨度箱梁橋取得發(fā)展，同樣適用于其他橋梁，例如跨

93、度較短橋梁和其他類型跨度區(qū)域。這是很重要的，因?yàn)樾枰獧z測那些小跨度梁，他們構(gòu)成所有橋梁的</p><p>　　大部分結(jié)構(gòu)。表1 傾角儀的主要特性</p><p>　　選定的傾角儀類型：偉倫Zerotronic ± 1 °[9]。其準(zhǔn)確度為1 microradian（μrad），相當(dāng)于一毫米每公里，是一個(gè)非常小的旋轉(zhuǎn)值。對于一個(gè)通常高度連續(xù)梁的中跨， 1 / 2000

94、0的跨中撓度，將導(dǎo)致最大約150μrad的旋轉(zhuǎn)，或0.15毫弧度（mrad）。 電子儀器潛在的一個(gè)問題是他們的測量結(jié)果可能隨時(shí)間漂移。為量化和控制這個(gè)問題，設(shè)計(jì)了一種機(jī)械裝置，允許傾角為180 °旋轉(zhuǎn)正是在一水平面上（圖4）。每個(gè)傾角儀的漂移可以通過比較獲得的初始值和旋轉(zhuǎn)位置與以前獲得值簡單地獲得。到目前為止，我們觀察到工程中使用的那種傾角儀的類型對漂流不是很敏感。</p><p>　　5.曼

95、圖橋的測試設(shè)備</p><p>　　一些采用平衡懸臂施工的橋梁，在實(shí)際使用中的狀態(tài)并不理想[2,7,10]，為了查清原因，對曼圖橋的變形發(fā)展做精密監(jiān)控。這些橋跨設(shè)計(jì)時(shí)考慮了最近的關(guān)于后期張拉量的建議[7,10,13]。監(jiān)控從1997年建橋時(shí)開始，2001年通車后會(huì)繼續(xù)跟蹤監(jiān)控。偏轉(zhuǎn)監(jiān)控包含公路部門提供的地形水準(zhǔn)、一個(gè)覆蓋兩跨整個(gè)跨度的流體靜力學(xué)水準(zhǔn)系統(tǒng)以及北橋主跨上的傾角儀網(wǎng)。為了便于比較測量值，工程師的記錄數(shù)據(jù)

96、要同步收集。觀測的信息將用于改善設(shè)計(jì)標(biāo)準(zhǔn)，尤其是關(guān)于后張拉量[7,10,11,12,13]。</p><p>　　一個(gè)數(shù)據(jù)提取程序會(huì)驅(qū)動(dòng)自動(dòng)監(jiān)控系統(tǒng)，并將數(shù)據(jù)存儲(chǔ)。這個(gè)系統(tǒng)可以同步控制不同類型的傳感器，目前控制著傾角儀和熱傳感器。這個(gè)電腦程序控制所有的測量設(shè)備，它提供了一個(gè)靈活的框架模式，允許后期增加新型傳感器和數(shù)據(jù)收集系統(tǒng)。LabView的使用給予使用者實(shí)驗(yàn)室級(jí)別的設(shè)備和分析優(yōu)勢。數(shù)據(jù)收集系統(tǒng)可以在普通配置的電

97、腦上運(yùn)行，因特爾486/66兆赫的處理器、16兆內(nèi)存、500兆硬盤、WindowsNT的系統(tǒng)。所有傳感器的數(shù)據(jù)一分鐘收集一次，之后以壓縮格式存儲(chǔ)在硬盤里。系統(tǒng)安置在3號(hào)墩上部的箱梁里（圖5）。它能抵抗嚴(yán)峻的氣候條件并且在電力供應(yīng)后自動(dòng)工作，斷電在施工階段頻頻發(fā)生。</p><p><b>　　6.傳感器</b></p><p>　　圖5（a）給出了北橋主跨上傾角儀的位

98、置。①和⑤傳感器安置在支撐軸上，③和④號(hào)分別在1/4和3/4跨，②號(hào)在1/8跨處。從橫截面看，傳感器安置在北腹板，高度與節(jié)目的重心對應(yīng)（圖5）。傳感器通過單根RS-485電纜與位于①號(hào)傾角儀附近的數(shù)據(jù)中心相連。早在橋梁施工階段就已經(jīng)開始監(jiān)控。①、②和③號(hào)傾角儀安裝于橋跨合龍前。在這種特殊施工方法的不同施工階段，角度的變化范范圍較寬，因此測量的結(jié)果不是很直觀。</p><p>　　通過合成橋長方向測量的旋轉(zhuǎn)，可以確

99、定偏轉(zhuǎn)的形式。盡管合成方法在原理上簡明易懂，但必須仔細(xì)計(jì)入荷載類型和可能的測量誤差[8,16]。</p><p>　　熱傳感器埋置在混凝土內(nèi)，這樣可以計(jì)入模板后來澆筑幾何調(diào)整的溫度作用。圖6是熱傳感器在主跨中的布置圖。與圖5傾角儀測量不同，溫度測量時(shí)針對同一個(gè)截面。根據(jù)施工的需要，傳感器在澆筑前預(yù)置在模板內(nèi)，在拆模后即可進(jìn)行測量。在每個(gè)截面上，九個(gè)傳感器中的七個(gè)（圖6中的黑色）由中央數(shù)據(jù)集成系統(tǒng)自動(dòng)控制測量。&l

100、t;/p><p><b>　　7.檢測結(jié)果</b></p><p>　　圖7是傾角儀從1997年九月底導(dǎo)十一月的第三個(gè)星期的測量結(jié)果。所有傾角儀在這段時(shí)間內(nèi)工作良好，其中測量間斷的部分，如十月初，是因?yàn)樵谑┕げ僮髦邢到y(tǒng)暫時(shí)斷電所致。結(jié)果整體的對稱，見①和⑤、③和④，表面設(shè)備在那段時(shí)間里的偏動(dòng)并不明顯。根據(jù)傾角儀的測量結(jié)果，在觀察階段，橋的最大撓曲在40毫米左右。在以后其他

101、測量結(jié)果的輔助下，更精確的數(shù)值可以計(jì)算出來。在圖上可以看到在幾天內(nèi)偏差的幾個(gè)上升階段及對應(yīng)的下降階段。這意味著需要對變形持續(xù)的監(jiān)測，以解釋這現(xiàn)象。從施工的角度來說，測量階段很繁忙，這個(gè)階段進(jìn)行著以下工作：混凝土的最后澆筑、實(shí)施千斤頂對橋的水平頂撐以補(bǔ)償一些墩的離心以及張拉連續(xù)預(yù)應(yīng)力筋和支索纜的留置（圖3），因此，解讀測量結(jié)果有一定的難度。將來的測量對解讀測量結(jié)果會(huì)有很大的幫助。</p><p>　　圖8是九月份的