Category: Structural Steel

Category: Structural Steel Erection of Cable-Suspended Bridges

The ease of erection of suspension bridges is a major factor in their use for long spans. Once the main cables are in position, they furnish a stable working base or platform from which the deck and stiffening truss sections can be raised from floating barges or other equipment below, without the need for auxiliary falsework. For the Severn Bridge, for example, 60-ft box-girder

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Category: Structural Steel Seismic Analysis of Cable-Suspended Structures

For short-span structures (under about 500 ft) it is commonly assumed in seismic analysis that the same ground motion acts simultaneously throughout the length of the structure. In other words, the wavelength of the ground waves are long in comparison to the length of the structure. In long-span structures, such as suspension or cable-stayed bridges, however, the structure could be subjected to different motions

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Category: Structural Steel Aerodynamic Analysis of Cable-Suspended Bridges

The wind-induced failure on November 7, 1940, of the Tacoma Narrows Bridge in the state of Washington shocked the engineering profession. Many were surprised to learn that failure of bridges as a result of wind action was not unprecedented. During the slightly more than  12 decades prior to the Tacoma Narrows failure, 10 other bridges were severely damaged or destroyed by wind action

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Category: Structural Steel Preliminary Design of Cable-Stayed Bridges

In general, the height of a pylon in a cable-stayed bridge is about 1⁄6 to 1⁄8 the main span. Depth of stayed girder ranges from 1⁄60 to 1⁄80 the main span and is usually 8 to 14 ft, averaging 11 ft. Live-load deflections usually range from 1⁄400 to 1⁄500 the span. To achieve symmetry of cables at pylons, the ratio of

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Category: Structural Steel Cable-Stayed Bridge Analysis

The static behavior of a cable-stayed girder can best be gaged from the simple, two-span example of Fig. 15.54. The girder is supported by one stay cable in each span, at E and F, and the pylon is fixed to the girder at the center support B. The static system has two internal cable redundants and one external support redundant. If the cable

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Category: Structural Steel Self-Anchored Suspension Bridges

Self-anchored suspension bridges differ from the type discussed in Arts. 15.16  only in that external anchorages are dispensed with (see Art. 15.3). Unlike the externally anchored type, self-anchored suspension bridges may properly be analyzed by the elastic theory, since the effect of distortions of the structural geometry under live load is practically eliminated. The structure is also not stressed by uniform temperature change

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Category: Structural Steel Suspension-Bridge Analysis

Structural analysis of a suspension bridge is that step in the design process whereby, for given structural geometry, materials, and sizes, the moments and shears in stiffening trusses, axial loads in cables and suspenders, and deflections of all elements are determined for given loads and temperature changes. The stress analysis usually is carried out in two broad categories: static and dynamic. Static Analysis—Elastic

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Category: Structural Steel Statics of Cables

The following summary of elementary statics of cables applies to completely flexible and inextensible cables but includes correction for elastic stretch. The formulas derive from the fundamental differential equation of a cable shape H  horizontal component of   tension produced by w w  distributed load, which may vary with x Two cases are treated: catenary, the shape taken by a cable when

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