1、附录：外文翻译 Evolvement of bridge Engineering,brief review Among the early documented reviews of construction materials and structure types are the books of Marcus Vitruvios Pollio in the first century B.C.The basic principles of statics were developed by the Greeks , and were exemplified in works and ap
2、plications 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 rapidly toward the end of the seventeenth century
3、 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 on stone and wood as the first bridge-build
4、ing 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 was not introduced in bridge construction u
5、ntil 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-circular , with flat arches beginning to domina
6、te 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 changed much ,but the theoretical treatment
7、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 arches, and showed that three redundant p
8、arameters 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 principles og bridge design : convenience(servicea
9、bility) ,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 Russia during the nineteenth century ,pr
10、ompted 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 ,although the first documented use of iron i
11、n 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 bridge was built across the Erie Canal a
12、t 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 , supplemented by a method for calculating th
13、e 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 in Hassfurt, Germany, with a center s
14、pan 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 magnitudes of 1711 feet (521.5m). At abo
15、ut 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 completed between 1874 and 1883. Among the
16、 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 introduced the three-moment equations. T
17、he Impetus of New Materials Since 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 uses are almost unlimited . Where
18、ver 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 beginning of this century imposed new ana
19、lytical 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 between joint moments and angular
20、 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 simple expression for each iteration
21、 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-plastic range , also known as loa
22、d 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 , mainly in Germany , with the center of activity shifting to Eng
23、land and the United States after World War .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 Reinforced Concrete Bridge Members
24、“ 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 development of ultimate design specifi
25、cations .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 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 .
