change in air temperature. To clarify its effect, let´s assume that a steel bridge 100 m long was erected in winter at an average temperature of 2oC. On a summer day, when the air temperature reaches 32oC, the bridge lengthens, since all bodies expand when heated. The increase in length of the bridge can be computed to be only 3 cm. It is indeed small, one three thousandths of the bridge´s length, however, if the bridge is anchored to abutments that do not allow this thermal expansion, the abutments will push on the bridge to reduce its length by 3 cm. And unfortunately steel is so stiff that the compressive load uses up half the strength of the steel therefore, the bridge´s resistance weakens. And for engineers, there is only one way of avoiding this dangerous overstress: one of the bridge´s ends must be allowed to move - to permit the thermal expansion. So while gravity loads must be fought by increasing the strength and stiffness of a structure, thermal loads
Guidelines for nominations state that each property should be compared with properties of the same type dating from the same period, both within and outside the nominating State Party's borders. For the purpose of this contextual essay, bridge design and construction is dealt with chronologically by material and by type. In addition to the obvious evaluation factors as age, rarity, integrity, and the fame of the builder, consideration also is given to the substructure (piers, abutments, foundation), the superstructure (beam, arch, truss, suspension, and combinations thereof), the materials of construction (their strength and properties), the evolution of construction techniques, and whether the bridge advanced structural theory or methods of evaluating material behaviour. Bridges discussed in this essay illustrate important types or technological turning points and are listed at the end. Some, like the Pont du Gard (France) and the Iron Bridge (UK), are already
Lusas Bridge Professional (FEM) Lusas Main structural analysis TASSU T.Palosaari Prestressed concrete beam analysis, stresses and cracking KATA WSP Detailed structure analysis PILG WSP Pile force analysis Tekla Structures v13 Tekla Structural design of abutments and pylon, drawings AutoCAD Autodesk Drawings Final structural design Tekla Structures v13 Tekla General concept of bridge, drawings of the structure Lusas Bridge FEM Lusas Structural analysis AutoCAD Autodesk some drawings MathCad PTC Mathematical analysis, e.g. prestressing and concrete creep
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