Shell Flashcards
A thin, curved plate structure, shaped to transmit applied forces by compressive, tensile, and shear stresses acting in the plane of the surface.
Shell
A shell structure constructed of reinforce concrete.
Thin Shell
A surface generated by sliding a plane curve along a straight line or over another plane curve.
Translational Surface
A surface generated by sliding a straight line along a plane curve, or vice versa. Depending on the curve, a cylindrical surface may be circular, elliptic, or parabolic. Because of its straight-line geometry, a cylindrical surface can be regarded as being either a translational or a ruled surface.
Cylindrical Surface
A rigid cylindrical shell structure.
Barrel Structure
- If the length of a barrel shell is three or more times its transverse span, it behaves as a deep beam with a curved section spanning in the longitudinal direction.*
- If it is relatively short, it exhibits archlike action, Tie rods, transverse rigid frames, or the like are required to counteract the ouward thrusts of the arching action.*
The compressive, tensile, and shear stresses acting in the plane of the surface of a shell structure. A shell can sustain relatively large forces if uniformly applied. Because of its thinness, however, a shell has little bending resistance and is unsuitable for concentrated loads.
Membrane Stresses
A surface generated by sliding a vertical parabola with downward curvature along a perpendicular parabola with downward curvature. Its horizontal sections are ellipses while its vertical sections are parabolas.
Elliptic Paraboloid
A surface generated by sliding a parabola with downward curvature along a parabola with upward curvature, or by sliding a straight-line segment with its ends on two skew lines. It can be consisdered to be both a translational and a ruled surface.
Hyperbolid Paraboloid, Hypar
A surface all of whose intersections by planes are either parablas and ellipses or parabolas and hyperbolas.
Paraboloid
A surface having an upward curvature in one direction and a downward curvature in the perpendicular direction. In a saddle-surfaced shell structure, regions of downward curvature exhibit archlike action, while regions of upward curvature behave as a cable structure. If the edges of the surface are not supported, beam behavior may also be present.
Saddle Surface
Having opposite curvatures at a given point.
Anticlastic
A surface generated by the motion of a straight line. Because of its straight-line geometry, a ruled surface is generally easier to form and construct than a rotational or translational surface,
Ruled Surface
A ruled surface generated by sliding a straight line with one end on a straight-line segment and the other on a plane curve. Depending on the curve, a conoid may be circular, elliptic or parabolic.
Conoid
A surface having a finite center with certain plane sections that are hyperbolas and others that are circles or ellipses.
Hyperboloid
A ruled surface generated by sliding an inclined line segment on two horizontal circles. Its vertical sections are hyperbolas.
One-sheet hyperboloid
A surface generated by rotating a plane curve about an axis.
Rotational Surface
Having similar curvatures at a given point.
Synclastic
A rotational surface generated by the revolution of a circular arc about a vertical axis.
Spherical Surface
A rotational surface generated by the revolution of a half ellipse about a vertical axis.
Elliptical Surface
A rotational surface generated by the revolution of a parabola about a vertical axis.
Parabolic Surface
A doughnut-shaped surface generated by the revolution of a circle about an exterior line lying in its plane.
Torus
