Folded plate and shell structures are thin-walled building structures that are lightweight yet rigid. Folded plate roofs use simpler calculations and formwork than shells. Modern folded plates are made of cast-in-place or precast concrete or steel. Shell structures come in various types including concrete shells, lattice shells, and membrane structures. Common shell structures include hyperbolic shells, parabolic shells, and cylindrical shells, with examples like the Calgary Saddledome. Paraboloids are a type of curved surface that can be elliptical, hyperbolic, or a combination to create rigid structural forms.

1. Structural basics in architecture

2. FOLDED SLAB ROOFS
• A thin-walled building structure of the shell type
• Movable form work can be employed.
• Form work required is relatively simpler.
• Design involves simpler calculations.
• Folded plate consumes more material than shells.

3. Folded slab roof
• Modern folded plate structures are typically
made of cast in site or precast reinforced
concrete, or steel plate.
Prismatic:
Rectangular
plates.
Pyramidal: Non-
rectangular
plates.
Prismoidal:
Triangular or
trapezoidal plates

5. Folded plate hut-japan

6. Air force academy chapel u.s.a.

7. Stairs....

8. CONCEPT OF SHELLS
• Thin shell structures are also called plate and shell structures.
• They are Light weight constructions using shell elements.

9. Thin shells-types
• Concrete shells- monolithic dome or stressed ribbon bridge
or saddle roof.
• Lattice shell structures(grid shell)-geodesic dome or
hyperboloid structure.
• Membrane structures- fabric structures, other tensile
structures, cable domes, pneumatic structures.

10. Thin shells - examples
• Concrete shell-
Deitingen Service
Station
• Membrane structures-
Birdair

11. Double curve shells
• Curved surface shell
structures can be used
to create very useful,
lightweight, rigid
structural forms.

12. Double curve shells

13. CYLINDERICAL SHELLS

14. Hyperbolic shells
• Doubly curved surface- shape of a saddle.
• It has a convex form along one axis and
concave form on along the other.
• Easy to construct using a series of straight
structural members
• Constructed using concrete.
• The curvature reduces its tendency to buckle
in compression and achieves stiffness.

17. Parabolic shells
• Series of parabolas stung together.
• The use of reinforcing steel in the upward
curvature of the parabola allows for the
tensile forces to flow into first the neutral sag,
or catenary then the thrust of the forces flow
into the compression on the downward
parabola.
• Both the axial parabolas are compressed and
in tension.

18. Saddle dome in Calgary, Alberta

19. Lee valley velopark, Londan

20. Parabolic shells

21. PARABOLOID
A paraboloid is a particular kind of three-dimensional
surface. In the simplest case, it is the revolution of a
parabola along its axis of symmetry. This kind of surface
will open upwards in both sideways dimensions. A
hyperbolic paraboloid will open upward in one dimension
and downward in the other, resembling a saddle. Like in a
two-dimensional parabola, scaling factors can be applied
to the curvature of a paraboloid.
y = x2
Examples :
• TWA terminal,NYC Intl. Airport
•Zeiss Planatarium,Germany
• l'oceanogràfic,Spain
The variants of Paraboloids are:
•Elliptical paraboloid (silmilar to paraboloid)
•Hyperbolic “

24. Hyperbolic:
A saddle-shaped quadric surface whose sections by
planes parallel to one coordinate plane are
hyperbolas while those sections by planes
parallel to the other two are parabolas if proper
orientation of the coordinate axes is assumed
In simple words, I is a combination of hyperbolae
and parabola within a single entity.
Examples:
•Lee Valley Velo Park
•House by James R. Mowry
•Scotiabank Saddledome,Canada

26. The end