橋梁畢業(yè)設計外文原文及翻譯

1、外文文獻翻譯, and were exemplified in works and applications by Leonardo da Vinci,Cardeno,and Galileo.In the fifteenth and sixteenth century, engineers seemed to be unaware of this record , and relied solely on experience and tradition for building bridges and aqueducts .The state of the art changed rapid

2、ly toward the end of the seventeenth century when Leibnitz, Newton, and Bernoulli introduced mathematical formulations. Published works by Lahire (1695)and Belidor (1792) about the theoretical analysis of structures provided the basis in the field of mechanics of materials .Kuzmanovic(1977) focuses

3、on stone and wood as the first bridge-building materials. Iron was introduced during the transitional period from wood to steel .According to recent records , concrete was used in France as early as 1840 for a bridge 39 feet (12 m) long to span the Garoyne Canal at Grisoles, but reinforced concrete

4、was not introduced in bridge construction until the beginning of this century . Prestressed concrete was first used in 1927.Stone bridges of the arch type (integrated superstructure and substructure) were constructed in Rome and other European cities in the middle ages . These arches were half-circu

5、lar , with flat arches beginning to dominate bridge work during the Renaissance period. This concept was markedly improved at the end of the eighteenth century and found structurally adequate to accommodate future railroad loads . In terms of analysis and use of materials , stone bridges have not ch

6、anged much ,but the theoretical treatment was improved by introducing the pressure-line concept in the early 1670s(Lahire, 1695) . The arch theory was documented in model tests where typical failure modes were considered (Frezier,1739).Culmann(1851) introduced the elastic center method for fixed-end

7、 arches, and showed that three redundant parameters can be found by the use of three equations of coMPatibility.Wooden trusses were used in bridges during the sixteenth century when Palladio built triangular frames for bridge spans 10 feet long . This effort also focused on the three basic principle

8、s og bridge design : convenience(serviceability) ,appearance , and endurance(strength) . several timber truss bridges were constructed in western Europe beginning in the 1750s with spans up to 200 feet (61m) supported on stone substructures .Significant progress was possible in the United States and

9、 Russia during the nineteenth century ,prompted by the need to cross major rivers and by an abundance of suitable timber . Favorable economic considerations included initial low cost and fast construction .The transition from wooden bridges to steel types probably did not begin until about 1840 ,alt

10、hough the first documented use of iron in bridges was the chain bridge built in 1734 across the Oder River in Prussia . The first truss completely made of iron was in 1840 in the United States , followed by England in 1845 , Germany in 1853 , and Russia in 1857 . In 1840 , the first iron arch truss

11、bridge was built across the Erie Canal at Utica .The Impetus of Analysis The theory of structures The theory of structures ,developed mainly in the ninetheenth century,focused on truss analysis, with the first book on bridges written in 1811. The Warren triangular truss was introduced in 1846 , supp

12、lemented by a method for calculating the correcet forces .I-beams fabricated from plates became popular in England and were used in short-span bridges.In 1866, Culmann explained the principles of cantilever truss bridges, and one year later the first cantilever bridge was built across the Main River

13、 in Hassfurt, Germany, with a center span of 425 feet (130m) . The first cantilever bridge in the United States was built in 1875 across the Kentucky River.A most impressive railway cantilever bridge in the nineteenth century was the First of Forth bridge , built between 1883 and 1893 , with span ma

14、gnitudes of 1711 feet (521.5m).At about the same time , structural steel was introduced as a prime material in bridge work , although its quality was often poor . Several early examples are the Eads bridge in St.Louis ; the Brooklyn bridge in New York ; and the Glasgow bridge in Missouri , all compl

15、eted between 1874 and 1883.Among the analytical and design progress to be mentioned are the contributions of Maxwell , particularly for certain statically indeterminate trusses ; the books by Cremona (1872) on graphical statics; the force method redefined by Mohr; and the works by Clapeyron who intr

16、oduced the three-moment equations.The Impetus of New MaterialsSince the beginning of the twentieth century , concrete has taken its place as one of the most useful and important structural materials . Because of the coMParative ease with which it can be molded into any desired shape , its structural

17、 uses are almost unlimited . Wherever Portland cement and suitable aggregates are available , it can replace other materials for certain types of structures, such as bridge substructure and foundation elements .In addition , the introduction of reinforced concrete in multispan frames at the beginnin

18、g of this century imposed new analytical requirements . Structures of a high order of redundancy could not be analyzed with the classical methods of the nineteenth century .The importance of joint rotation was already demonstrated by Manderla (1880) and Bendixen (1914) , who developed relationships

19、between joint moments and angular rotations from which the unknown moments can be obtained ,the so called slope-deflection method .More simplifications in frame analysis were made possible by the work of Calisev (1923) , who used successive approximations to reduce the system of equations to one sim

20、ple expression for each iteration step . This approach was further refined and integrated by Cross (1930) in what is known as the method of moment distribution .One of the most import important recent developments in the area of analytical procedures is the extension of design to cover the elastic-p

21、lastic range , also known as load factor or ultimate design. Plastic analysis was introduced with some practical observations by Tresca (1846) ; and was formulated by Saint-Venant (1870) , The concept of plasticity attracted researchers and engineers after World War I , mainly in Germany , with the

22、center of activity shifting to England and theUnited States after World War n .The probabilistic approach is a new design concept that is expected to replace the classical deterministic methodology.A main step forward was the 1969 addition of the Federal Highway Adiministration (FHWA)”Criteria for R

23、einforced Concrete Bridge Members “ that covers strength and serviceability at ultimate design . This was prepared for use in conjunction with the 1969 American Association of State Highway Offficials (AASHO) Standard Specification, and was presented in a format that is readily adaptable to the deve

24、lopment of ultimate design specifications .According to this document , the proportioning of reinforced concrete members ( including columns ) may be limited by various stages of behavior : elastic , cracked , and ultimate . Design axial loads , or design shears . Structural capacity is the reaction

25、 phase , and all calculated modified strength values derived from theoretical strengths are the capacity values , such as moment capacity ,axial load capacity ,or shear capacity .At serviceability states , investigations may also be necessary for deflections , maximum crack width , and fatigue .Brid

26、ge TypesA notable bridge type is the suspension bridge , with the first example built in the United States in 1796. Problems of dynamic stability were investigated after the Tacoma bridge collapse , and this work led to significant theoretical contributions Steinman ( 1929 ) summarizes about 250 sus

27、pension bridges built throughout the world between 1741 and 1928 .With the introduction of the interstate system and the need to provide structures at grade separations , certain bridge types have taken a strong place in bridge practice. These include concrete superstructures (slab ,T-beams,concrete

28、 box girders ), steel beam and plate girders , steel box girders , composite construction , orthotropic plates , segmental construction , curved girders ,and cable-stayed bridges . Prefabricated members are given serious consideration , while interest in box sections remains strong .Bridge Appearanc

29、e and AestheticsGrimm ( 1975 ) documents the first recorded legislative effort to control the appearance of the built environment . This occurred in 1647 when the Council of New Amsterdam appointed three officials . In 1954 , the Supreme Court of the United States held that it is within the power of

30、 the legislature to determine that communities should be attractive as well as healthy , spacious as well as clean , and balanced as well as patrolled . The Environmental Policy Act of 1969 directs all agencies of the federal government to identify and develop methods and procedures to ensure that p

31、resently unquantified environmental amentities and values are given appropriate consideration in decision making along with economic and technical aspects .Although in many civil engineering works aesthetics has been practiced almost intuitively , particularly in the past , bridge engineers have not

32、 ignored or neglected the aesthetic disciplines .Recent research on the subject appears to lead to a rationalized aesthetic design methodology (Grimm and Preiser , 1976 ) .Work has been done on the aesthetics of color ,light ,texture , shape , and proportions , as well as other perceptual modalities

33、 , and this direction is both theoretically and empirically oriented .Aesthetic control mechanisms are commonly integrated into the land-use regulations and design standards . In addition to concern for aesthetics at the state level , federal concern focuses also on the effects of man-constructed en

34、vironment on human life , with guidelines and criteria directed toward improving quality and appearance in the design process . Good potential for the upgrading of aesthetic quality in bridge superstructures and substructures can be seen in the evaluation structure types aimed at improving overall a

35、ppearance .LOADS AND LOADING GROUPSThe loads to be considered in the design of substructures and bridge foundations include loads and forces transmitted from the superstructure, and those acting directly on the substructure and foundation .AASHTO loads . Section 3 of AASHTO specifications summarizes

36、 the loads and forces to be considered in the design of bridges (superstructure and substructure ) . Briefly , these are dead load ,live load , iMPact or dynamic effect of live load , wind load , and other forces such as longitudinal forces , centrifugal force ,thermal forces , earth pressure , buoy

37、ancy , shrinkage and long term creep , rib shortening , erection stresses , ice and current pressure , collision force , and earthquake stresses .Besides these conventional loads that are generally quantified , AASHTO also recognizes indirect load effects such as friction at expansion bearings and s

38、tresses associated with differential settlement of bridge components .The LRFD specifications divide loads into two distinct categories : permanent and transient .Permanent loadsDead Load : this includes the weight DC of all bridge components , appurtenances and utilities, wearing surface DW and fut

39、ure overlays , and earth fill EV. Both AASHTO and LRFD specifications give tables summarizing the unit weights of materials commonly used in bridge work .Transient LoadsVehicular Live Load (LL)Vehicle loading for short-span bridges :considerable effort has been made in the United States and Canada t

40、o develop a live load model that can represent the highway loading more realistically than the H or the HS AASHTO models . The current AASHTO model is still the applicable loading.橋梁工程和橋梁美學橋梁工程的發(fā)展概況早在公元前1世紀，Marcus Vitrucios Pollio 的著作中就有關于建筑材料和結(jié)構(gòu)類型的記載和 評述。后來古希臘人創(chuàng)立了靜力學的基本原理， Leonardo da Vinci 、Carden

41、o 和 Galileo 等 人在工作和應用中也證實了這些原理的正確性。 而在 15世紀至 16世紀期間， 工程師們似乎 并沒有注意到這些文字記載，只是單憑經(jīng)驗和傳統(tǒng)來建造橋梁和渡槽。到了17 世紀末，隨著 Leibnitz 、Newton 和 Bernoulli 的數(shù)學理論的創(chuàng)立， 橋梁建筑技術得到了快速發(fā)展。 Lahire （1695）和belidor（ 1729）出版的關于結(jié)構(gòu)理論分析的著作為材料力學領域奠定了基礎。Kuzmanovic （1977）指出，石材和木材是橋梁建筑最早采用的材料。在從木材到鋼材的轉(zhuǎn) 變過程中，鐵作為一種過渡材料被用于橋梁建筑中。根據(jù)近期的記載。早在1840 年，

42、法國就在 Grisoles 建造了一座跨度為 39英尺（ 12米）的橫跨 Garoyne 運河的混凝土橋梁，但 鋼筋混凝土橋直到本世紀初才出現(xiàn)，而預應力混凝土到 1 927年才開始使用。早在中世紀， 羅馬和歐洲的其他一些城市開始建造集上下部結(jié)構(gòu)于一體的半圓弧石拱橋，而文藝復興時期則是坦拱逐漸占主導地位。這種觀念在 18 世紀末有了明顯的改進，并發(fā)現(xiàn)其 在結(jié)構(gòu)上能適應后來的鐵路荷載。在材料的分析和使用上，石拱橋至今沒有發(fā)生大的變化，但是由于在17世紀70年代初期（Lahire,1965 ）引進了壓力線的概念，使得拱橋的理論分析 得到了改進。 通過模型試驗， 有關拱結(jié)構(gòu)的主要失效形式的理論得到了證

43、實 （Frezier ,1739）。 對于無鉸拱， Culmann （1851 ） 引進了彈性中心的方法，顯示了可用三個協(xié)調(diào)方程求解三個 多余參數(shù)。當 palladio 建造了一座跨度為 10英尺的三角形木制框架橋后， 16世紀開始，木桁架在橋梁 中得到應用。這些設計同樣遵循橋梁設計的三個基本原則：方便（實用性）、美觀和耐久性（強度）。 18 世紀 50 年代西歐建造了若干座支承于石制橋墩上的木桁架橋，其跨度達到 200英尺（61 米）。 19世紀期間，美國和俄羅斯由于其跨越主要河流的需要，而且兩國都具有豐 富的適用于建橋的木材資源， 因此木制橋梁在美、 俄兩國有可能取得更為顯著的成績。 木制

44、 橋梁具有良好的經(jīng)濟性，因為其初期投資較低，施工速度較快。盡管有文獻記載，早在1734年，在普魯士就修建了第一座橫跨Oder河的鐵鏈橋，但從木橋到鋼橋的過渡大概開始于 1840 年。美國于 1840 年建成了第一座全鐵桁架橋， 其后，英格蘭、 德國和俄羅斯分別于 1845 年、 1853年和 1857年也建成了鐵桁架橋。 1840 年，第一座鐵桁 架拱橋出現(xiàn)在 Utica 的 Erie 運河上。理論分析的推動作用主要從 19 世紀發(fā)展起來的機構(gòu)分析理論著重于桁架的分析，首部關于橋梁工程的著作于 1811年出版。 1846年出現(xiàn)了一種 Warren 三角形桁架和計算這種桁架精確內(nèi)力的分析方法。

45、用板件組合而成的工字形梁在英國逐漸普及并在小跨度橋梁中得到應用。1866 年 Culmann 闡述了懸臂桁架橋的原理，一年后在德國的 Hassfurt 的 Main 河上就建造 了首座主跨跨度達 425 英尺（ 130 米）的懸臂梁橋。美國的首座懸臂梁橋于 1875 年建于 Kentucky 河上。 19 世紀最引人注目的鐵路懸臂梁橋要數(shù)Firth of Forth 橋， 此橋建于 1883 年至 1890年間，跨度達 1，711英尺（ 521.5米）大約就在這一時期，結(jié)構(gòu)鋼在橋梁工程中作 為一種主要材料被推廣應用，盡管此時鋼材的性能大都較差。幾個早期的工程實例是：（1）St.Louis 的

46、Eads 橋；（ 2）New York 的 Brooklyn 橋；（ 3）Missouri 的 Glasgow 大橋，這些 橋都建于 1874 年至 1883 年間。談起對結(jié)構(gòu)分析河設計理論的改進特別應該提到： Maxwell 所作的貢獻，尤其是他在超靜 定桁架方面的工作； Cremona 關于圖解靜力學的著作（ 1872）；由 Mohr 重新定義的力法以 及 Clapeyron 提出的三彎矩方程新材料的推動作用自從 20 世紀初起，混凝土就是一直是最有效和最重要的建筑材料之一。由于混凝土可以較 容易地澆注成各種形狀的結(jié)構(gòu)物， 因此它在建筑上的使用價值幾乎是無限的。 只要有普通水 泥和合適的骨

47、料混凝土就可以替代其他材料建造某些類型的結(jié)構(gòu)， 諸如橋梁下部結(jié)構(gòu)及基礎 等。另外，在本世紀初， 鋼筋混凝土在多跨框架結(jié)構(gòu)中的應用對結(jié)構(gòu)分析提出了新的分析要求用Saint-Venant （1870） 系統(tǒng)地闡述了這種分析方法。第一次世界大戰(zhàn)以后，塑性的概念吸引著 二次世界大戰(zhàn)后， 隨著科研學術重心的 概率設計法是一種新的設計方法， 這19 世紀的古典分析方法不能用來分析高次靜定結(jié)構(gòu)。 Manderla （1880）和 Bendixen （1914） 論 證了節(jié)點轉(zhuǎn)角的重要性，提出了節(jié)點彎矩和轉(zhuǎn)角之間的關系，從而可求解未知的節(jié)點彎矩， 這種方法被稱為轉(zhuǎn)角撓度法。 Calisev （1923） 的工

48、作使得框架結(jié)構(gòu)的分析有可能進一步簡 化，他利用逐步近似的方法將方程組的求解簡化為一個簡單表達式的迭代計算。 Cross （1930） 進一步改進和歸納了這種方法，從而形成了彎矩分配法。 在結(jié)構(gòu)分析領域的近期發(fā)展中最重要的改進之一是將設計的范圍延伸到彈塑性范圍， 即所謂 的荷載因子法或極限狀態(tài)設計法。 Tresca （1846） 根據(jù)一些世紀觀察結(jié)果提出了塑性分析法， 研究人員和工程師們的注意力， 開始主要是在德國。 轉(zhuǎn)移， 英國和美國的科研人員對此進行了廣泛的研究。 種方法有望替代傳統(tǒng)的確定性方法。FHWA ）的“鋼筋混凝土橋梁勾踐設計 這本設計準則是與 “美國各州公路工作 它的表達方式使其很

49、容易適應極限狀一個主要的進步是 1969 版的美國聯(lián)邦公路管理局（準則” 中包括了強度和正常使用的極限狀態(tài)設計法。者協(xié)會（ AASHO ）” 1969 年的設計規(guī)范聯(lián)合使用的， 態(tài)設計規(guī)范的發(fā)展。 根據(jù)這本設計準則， 鋼筋混凝土勾踐 （包括柱）的配料可以通過其各個 階段的工作性能來限定： 彈性的、帶裂縫工作的極限狀態(tài)的。 設計是荷載作用效應，所有根 據(jù)作用荷載計算所得的量叫做設計值，如：設計彎矩、設計軸載或或設計剪力。結(jié)構(gòu)的承載 力被認為是結(jié)構(gòu)抗力方面的參數(shù)， 所有根據(jù)材料的理論強度計算得來并經(jīng)過修正得強度計算 值叫做結(jié)構(gòu)抗力值，如：彎矩抗力值（抵抗彎矩） ，軸力抗力值或剪力抗力值。在正常使用

50、 極限狀態(tài)下，需驗算構(gòu)件得撓度、最大裂縫寬度和疲勞強度。橋型 一種值得注意得橋型是吊橋，首座吊橋 1796 年建于美國。隨著 Tacoma 大橋得跨塌，動力 穩(wěn)定被作為問題來研究， 并取得了顯著得理論成果。 Steinman (1929) 總結(jié)了全世界建于 1741 年至 1928 年間得大約 250 座吊橋。隨著州際體系得建立和結(jié)構(gòu)等級分類的需要， 某些橋型在橋梁界占有重要的地位。 這些橋型 包括混凝土上部結(jié)構(gòu)(板橋、 T 梁橋、混凝土箱梁橋) 、鋼梁橋、鋼箱梁橋、組合界哦故、 正交異性板結(jié)構(gòu)、分段施工的結(jié)構(gòu)、 曲線梁橋和斜拉橋。 預制構(gòu)件受到了足夠的重視， 箱型 截面梁也占有重要的地位。橋

51、梁的外觀及橋梁美學Grimm(1975) 考證了歷史上首例關于控制建筑環(huán)境美學的立法記錄，這發(fā)生在1647 年，當時的新阿姆斯特丹委員會派三名官員負責此事。 1954 年，美國聯(lián)邦最高法院認為，立法機 關有權決定公共場所不但要有利于公眾健康，還要做到賞心悅目；不但要干凈，還要寬敞； 不但要通暢，還要布局均衡。 1969 年的環(huán)境政策法規(guī)要求聯(lián)邦政府各機構(gòu)對目前尚未量化 的環(huán)境舒適性指標提出評價方法，在考慮技術經(jīng)濟指標的同時，對美觀給予適當?shù)目紤]。 盡管在很多土木工程結(jié)構(gòu)中， 幾乎是憑直觀考慮美學問題， 尤其在過去， 但橋梁工程師們并 沒有忽略美學方面的訓練。最近關于的研究似乎可以得到一種美學設

52、計方法論( Grimm 和Preiser,1976)。有關顏色、光線、質(zhì)地、形狀、比例以及其他感知形態(tài)的美學研究已經(jīng)展開， 這個方向無論在理論上還是經(jīng)驗上都是明確的。美學控制機制一般都與土地使用規(guī)則和設計標準結(jié)合在一起。除了州政府關心結(jié)構(gòu)美學以 外，聯(lián)邦政府將主要精力集中在考慮人工環(huán)境對人類生活的影響上，以及制定準則和規(guī)范以指導設計者在設計過程中改進質(zhì)量和外觀。 從為了改進結(jié)構(gòu)整體外觀而進行的橋型評估中可 以看出，提高橋梁結(jié)構(gòu)美學質(zhì)量的潛力還是很大的。荷載及荷載組合在橋梁下部結(jié)構(gòu)和基礎設計中要考慮的荷載包括： 從上部結(jié)構(gòu)傳下來的荷載和直接作用于下 部結(jié)構(gòu)的基礎的荷載。AASHTO 荷載 AAS

53、HTO 規(guī)范第三部分總結(jié)了橋梁設計(上、下部結(jié)構(gòu))要考慮的荷載和 作用力。主要有：恒載、活載、活載沖擊力或動力作用、風荷載以及其他力如縱向力、 離心力、溫度力、土壓力、浮力收縮及徐變、拱肋縮短、安裝應力、冰及水流壓力、沖撞力 及地震應力。除了這些通常能夠量化大的典型荷載外，AASHTO 同樣認識到諸如活動支座處產(chǎn)生的摩擦以及由于橋梁勾踐的沉降差而產(chǎn)生的應力等間接荷載效應。LRFD 規(guī)范將荷載劃分為截然不同的兩種：長期荷載和短期荷載。 長期荷載荷載：包括所有橋梁構(gòu)件、器件及輔助設備、道路面層的凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單

54、位重量。 短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種比H或HS AASHTO模型更實際的代表高速公路活荷載的模型。到目前為止，AASHTO 模型仍被廣泛采用。長期荷載荷載：包括所有橋梁構(gòu)件、器件及輔助設備、道路面層的凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單位重量。短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種比 H 或 HS AASHTO 模 型更實際的代表高速公路活荷載的模型。到目前為止，AASHTO 模型仍被廣泛采用。長期荷載荷載：包括所有橋梁構(gòu)件、器件及輔助設備、道路面層的

55、凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單位重量。 短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種比 H 或 HS AASHTO 模 型更實際的代表高速公路活荷載的模型。到目前為止， AASHTO 模型仍被廣泛采用。 長期荷載 荷載：包括所有橋梁構(gòu)件、器件及輔助設備、道路面層的凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單位重量。 短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種比 H 或 HS AASHTO 模 型更實際的代表高

56、速公路活荷載的模型。到目前為止， AASHTO 模型仍被廣泛采用。長期荷載 荷載：包括所有橋梁構(gòu)件、器件及輔助設備、道路面層的凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單位重量。 短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種比 H 或 HS AASHTO 模 型更實際的代表高速公路活荷載的模型。到目前為止， AASHTO 模型仍被廣泛采用。長期荷載 荷載：包括所有橋梁構(gòu)件、器件及輔助設備、道路面層的凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單位重量。

57、 短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種比 H 或 HS AASHTO 模 型更實際的代表高速公路活荷載的模型。到目前為止， AASHTO 模型仍被廣泛采用。長期荷載 荷載：包括所有橋梁構(gòu)件、器件及輔助設備、道路面層的凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單位重量。 短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種比 H 或 HS AASHTO 模 型更實際的代表高速公路活荷載的模型。到目前為止， AASHTO 模型仍被廣泛采用。長期荷載 荷載：包括所有橋梁構(gòu)件、器件及輔助設備

58、、道路面層的凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單位重量。 短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種比 H 或 HS AASHTO 模 型更實際的代表高速公路活荷載的模型。到目前為止， AASHTO 模型仍被廣泛采用。 長期荷載 荷載：包括所有橋梁構(gòu)件、器件及輔助設備、道路面層的凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單位重量。 短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種比 H 或 HS AASHTO 模 型更

59、實際的代表高速公路活荷載的模型。到目前為止， AASHTO 模型仍被廣泛采用。長期荷載 荷載：包括所有橋梁構(gòu)件、器件及輔助設備、道路面層的凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單位重量。 短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種比 H 或 HS AASHTO 模 型更實際的代表高速公路活荷載的模型。到目前為止， AASHTO 模型仍被廣泛采用。 長期荷載 荷載：包括所有橋梁構(gòu)件、器件及輔助設備、道路面層的凈重及未來鋪裝重量、填土恒載。AASHTO 及 LRFD 規(guī)范都給出了表格，總結(jié)了橋梁工程重常用才兩的單位重量。 短期荷載汽車荷載 小跨度橋梁的汽車荷載： 美國和加拿大已致力于發(fā)展一種