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Economics of Bridgework: A Sequel to Bridge Engineering
John Alexander Low Waddell
No preview available - 2015
adopted amount anchor arm arch bascule Bridge Engineering bridgework cages caissons cantilever bridge carbon steel carry cent CHAPTER cheaper chords Chromium Class 60 cofferdam combined comparative economics compression members computations concrete consideration construction crossing curves dead load deck depth determine diagrams double-track economic span-length effect elastic limit electric-railway employed equal cost erection expensive eye-bars falsework feet flanges floor floor-system foundations girders greater hence highway bridges I-beams important increase involved latter layout length lineal foot live load long spans Low-Level material method Molybdenum nickel steel paint panels piers piles pin-connected plate-girder spans plates possible practice railroad railway bridges reinforced-concrete River rivets roadway Sand Sand Sand simple-truss spans single-track slab stresses stringers structure substructure superstructure suspension bridges Tensile tensile stress thereof timber tion total cost total weight track traffic transbordeur trestle trusses tunnel unit prices vertical weight of metal width
Page 232 - In concluding this chapter, the author desires to call attention to the fact that there is still a great deal to be learned about the...
Page 7 - ... gilt-edged." Small projects necessitate greater probable percentages of net earnings than do large ones ; and any possibility of a future reduction of income will call for a high estimate of net earning capacity. Finally, the measure of individual greed on the part of the investor will be found to be an important factor in the determination of the attractiveness of any suggested enterprise. Such investigations as the economics of an important project should generally be entrusted only to engineers...
Page 136 - Designing and detailing shall be done so as to avoid secondary stresses as far as possible. In ordinary trusses without subpaneling, no account usually need be taken of the secondary stresses in any member whose width measured in the plane of the truss is less than one-tenth of its length. Where this ratio is exceeded, or where subpaneling is used, secondary stresses due to deflection of the truss shall be computed.
Page 392 - Consistency. — The quantity of water used in mixing should be the least that will produce a plastic or workable mixture which can be worked into the forms and around the reinforcement. Under no circumstances...
Page 395 - American Society for Testing Materials and the American Society of Civil Engineers under the conditions noted in each case.
Page 287 - The center-bearing type, designed in accordance with good modern practice, offers more advantages than the rim-bearing type, and should always receive the first consideration in determining upon a design. It requires less power to turn, has a smaller number of moving parts, is less expensive to construct and maintain, requires less accurate construction than the rim-bearing bridge, and does not as easily get out of order. The structural and the operating or machinery parts are entirely separate,...
Page 253 - Study in the Designing and Construction of Elevated Railroads, with Special Reference to the Northwestern Elevated Railroad and the Union Loop Elevated Railroad of Chicago, Ill.," by JAL Waddell. (63) Vol. 38 (1897), pp. 41-77. "Recent Tests of Bridge Members,
Page 216 - ... afterward. This method of procedure has a great many advantages over that of raising the trusses first, viz.: there is a great saving in false work, as longer panels can be used; it permits bents to be placed directly under the panel points and the new floor system to be used for carrying traffic and running out material for the trusses; it permits the posts to be bolted to the floorbeams and released from the tackles on the travelers; it fixes the exact position of the shoes on the piers so...
Page 195 - At the same time the libelant offered a report of the department of plant and structures of the city of New York, showing the opening to be 60 feet wide.
Page 392 - The quantity of water used in mixing shall be the least amount that will produce a plastic or workable mixture which can be worked into the forms and around the reinforcement. Under no circumstances shall the consistency of the concrete be such as to permit a separation of the coarse aggregate from the mortar in handling. An excess of water will not be permitted, as it seriously affects the strength of the concrete and any batch containing such an excess will be rejected.