Basic Theory of Plates and Elastic Stability - Part 11

Tài liệu tham khảo giáo trình cơ học kết cấu trong ngành xây dựng bằng Tiếng Anh - Yamaguchi, E. “Basic Theory of Plates and Elastic Stability” Structural Engineering Handbook Ed. Chen Wai-Fah Boca Raton: CRC Press LLC, 1999 - Shell Structures
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Basic Theory of Plates and Elastic Stability - Part 11Miller, C.D. “Shell Structures”Structural Engineering HandbookEd. Chen Wai-FahBoca Raton: CRC Press LLC, 1999 Shell Structures 11.1 Introduction Overview • Production Practice • Scope • Limitations • Stress Components for Stability Analysis and Design • Materials • Ge- ometries, Failure Modes, and Loads • Buckling Design Method • Stress Factor • Nomenclature 11.2 Allowable Compressive Stresses for Cylindrical Shells Uniform Axial Compression • Axial Compression Due to Bending Moment • External Pressure • Shear • Sizing of Rings (General Instability) 11.3 Allowable Compressive Stresses For Cones Uniform Axial Compression and Axial Compression Due to Bending • External Pressure • Shear • Local Stiffener Buckling 11.4 Allowable Stress Equations For Combined Loads For Combination of Uniform Axial Compression and Hoop Compression • For Combination of Axial Compression Due to Bending Moment, M , and Hoop Compression • For Com- bination of Hoop Compression and Shear • For Combination of Uniform Axial Compression, Axial Compression Due to Bending Moment, M , and Shear, in the Presence of Hoop Compression, (fh = 0) • For Combination of Uniform Axial Compression, Axial Compression Due to Bending Moment, M , and Shear, in the Absence of Hoop Compression, (fh = 0) 11.5 Tolerances for Cylindrical and Conical Shells Shells Subjected to Uniform Axial Compression and Axial Compression Due to Bending Moment • Shells Subjected to External Pressure • Shells Subjected to Shear 11.6 Allowable Compressive Stresses Spherical Shells • Toroidal and Ellipsoidal Heads 11.7 Tolerances for Formed HeadsClarence D. Miller ReferencesConsulting Engineer, Further ReadingBloomington, IN11.1 Introduction11.1.1 OverviewMany steel structures, such as elevated water tanks, oil and water storage tanks, offshore structures,and pressure vessels, are comprised of shell elements that are subjected to compression stresses. Theshell elements are subject to instability resulting from the applied loads. The theoretical bucklingstrength based on linear elastic bifurcation analysis is well known for stiffened as well as unstiffenedcylindrical and conical shells and unstiffened spherical and torispherical shells. Simple formulas 1999 by CRC Press LLCchave been determined for many geometries and types of loads. Initial geometric imperfections andresidual stresses that result from the fabrication process, however, reduce the buckling strength offabricated shells. The amount of reduction is dependent on the geometry of the shell, type of loading(axial compression, bending, external pressure, etc.), size of imperfections, and material properties.11.1.2 Production PracticeThe behavior of a cylindrical shell is influenced to some extent by whether it is manufactured in a pipeor tubing mill or fabricated from plate material. The two methods of production will be referred toas manufactured cylinders and fabricated cylinders. The distinction is important primarily becauseof the differences in geometric imperfections and residual stress levels that may result from the twodifferent production practices. In general, fabricated cylinders may be expected to have considerablylarger magnitudes of imperfections (in out-of-roundness and lack of straightness) than the millmanufactured products. Similarly, fabricated heads are likely to have larger shape imperfections thanthose produced by spinning. Spun heads, however, typically have a greater variation in thicknessand greater ...