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AISC elgaaly pdf free download

AISC elgaaly pdf free download.Web Design Under Compressive Edge Loads.
Webs of rolled and built-up beams and girders can be subjected to local in-plane compressive patch loads. Examples are, wheel loads, loads from purlins and roller loads during construction. For practical and/or economic reasons, transverse stiffeners are to be minimized or avoided except at critical sections. It is, therefore, necessary to check the unstiffened web under the edge compressive loading to insure no localized failure will occur. They type of loading under consideration is shown in Fig. 1. The length of the loaded patch “c” can vary between being so small as to be assumed concentrated to so large it can be extended over the entire length of the web panel. The later case will be referred to as distributed-edge loading. The localized stresses due to edge loading can be combined with global stresses of bending and/or shear. During the past 50 years, tests have been performed by several investigators to study the web behavior under compressive edge loads. These loads are mostly of the type shown in Fig. 1. However, the compression of the web over a support bearing block, as in Fig. 2, was also investigated. Extensive analytical and experimental studies of the elastic buckling and ultimate strength of webs loaded, shown in Fig. 1, were carried out during the last 20 years. The purpose of this report is to summarize the available analytical and experimental studies and develop recommendations for the design of unstiffened webs under compressive edge loads.Local membrane stresses in the web under the load can reach the yield stress of the web material. The localized membrane yielding may not necessarily constitute failure, but eventually will induce web crippling, a localized wrinkling or folding of the web plate, shown in Fig. 3. During testing of thick webs, the girders sustained higher loads than those which caused membrane yielding and failed in the crippling mode. Inspection of the load deflection curves obtained from these tests reveal a change in slope at about the yield load, which is due to a significant membrane yielding of the web. In thin webs, crippling can occur prior to yielding. Rigorous analytical and numerical solutions for elastic buckling of thin web panels with assumed idealized conditions are available. Web buckling, however, is not synonymous with failure due to the post-buckling reserve of strength possessed by restrained thin panels. Little or no correlation between the theoretical buckling loads and the experimental failure loads can be established. Furthermore, during testing, it is very difficult, if not impossible, to define the buckling load. This is due to the initial out-of- plane crookedness of the web panel, unavoidable even under laboratory conditions. At the beginning of this century, Sommerfield 1 and Timoshenko 2 were the first to obtain approximate solutions for the buckling of a plate subjected to equal and opposite concentrated forces applied at the midpoints of the longitudinal edges, as in Fig. 4a. About 30 years later, Leggett 3 presented a more rigorous solution to the same problem. Recently, Khan and Walker 4 obtained solutions for this problem with the applied forces distributed over a finite length “c,” as shown in Fig. 4b. Girkman 5 was the first investigator to study the problem of buckling of a rectangular plate subjected to discrete edge loading at the middle of one longitudinal edge and supported at its two vertical edges. Zeltin 6 provided a more detailed study of the problem using energy methods.  AISC elgaaly pdf download.

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