The design loading for a structure is often specified in Codes (which provide only a general guide for design) The ultimate responsibility for the design lies with the structural engineer. In general, the structural engineer works with two types of codes: General Building Codes and Design Codes. o General Building Codes specify the requirements of governmental bodies for minimum design loads on structures and minimum standards for construction. o Design Codes provide detailed technical standards and are used to establish the requirements for the actual structural design. Dead Loads consist of the weights of the various structural members and the weights of any objects that are permanently attached to the structure. o For a building, the dead loads include the weights of the columns, beams, and girders, the floor slab, roofing, walls, windows, plumbing, electrical fixtures, and other miscellaneous attachments
Chapter 1 TYPES OF STRUCTURES AND LOADS (Topic: Structural Engineering, Structural Systems, & Loads) o In some cases, a structural dead load can be estimated satisfactorily from simple formulas based on the weights and sizes of similar structures. Through experience one can also derive a “feeling” for the magnitude of these loadings. Ordinarily, though, once the materials and sizes of the various components of the structure are determined, their weights can be found from tables that list their densities o Loads will have to be estimated in the initial phase of design. These estimates include nonstructural materials such as prefabricated facade panels, electrical and plumbing systems, etc. Estimates of dead loadings can be in error by 15% to 20% or more o Normally, the dead load is not large compared to the design load for simple structures such as a beam or a single-story frame. It becomes more important in multistory buildings (lower floors) Live Loads can vary both in their magnitude and location. They may be caused by the weights of objects temporarily placed on a structure, moving vehicles, or natural forces. o The minimum live loads specified in codes are determined from studying the history of their effects on existing structures. Usually, these loads include additional protection against excessive deflection or sudden overload. There are techniques for specifying the proper location of live loads on the structure so that they cause the greatest stress or deflection of the members Types of live loads include building loads, highway bridge loads, railroad bridge loads, impact loads, wind loads, snow loads, earthquake loads, loads from hydrostatic & soil pressures, etc Various Types of Live Loads o Building Loads : The floors of buildings are assumed to be subjected to Uniform Live Loads, which depend on the purpose for which the building is designed.
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- Fall '14
- Structural Engineering, Truss, loads, Structural load