History and Construction of Shell Structures

Study Notes

Shell Structures History

Shell structures began developing in the 1920s and 1930s as thin-shelled concrete structures for factories and marketplaces.
The Hayden Planetarium in NYC (1935) is an early example.

Shell Structures

The shape of the shell significantly impacts load distribution and stability. Types include single and double curvature.
Shell structures focus on creating lightweight structures that are disproportionate to the area they cover, similar to the thinness of an eggshell compared to its volume.
Applications for shell structures include: Museums, sports arenas, exhibition halls, cultural institutions, churches, and schools.

Shell Structures Construction Methods

Shell structures can be made using various methods including concrete, prestressed, pneumatic forming, traditional formwork, steel ribs and cables, wood ribs, membrane structures, and prefabricated shell elements.

Types of Shell Structures

Originally masonry and concrete, shell structures now encompass:
- Membrane Structures: Utilize tension in the material to create the form and load distribution.
  - Tensile Fabric: 3D form from tension.
  - Pneumatic Structures: Air-supported.
- Grid Shell: Strength from double curvature created by a grid or lattice.
  - Wood/Timber (Lattice): Example is the Mannheim Multihalle.
  - Cables or Steel:
  - Geodesic Dome:
- Thin-Shell Concrete: Curved or folded plates.

Membrane Structures

Tensile Fabric Structures: Tension creates form and load distribution.
- Pre-stressed Membranes: Fabric or rubber-like shells stretched over rigid frameworks and columns to form enclosures.
- Advantages: Lighter than conventional steel roofs, low energy costs due to natural sunlight, less structure, no support, and flexible space.
- Principles: Strength from tension, form determined by fabric shape, supporting structure geometry, and pretensioning of the fabric.
- Applications include pavilions, multi-purpose areas, and sunshades.
- Types of membrane structures:
  - Pre-stressed membranes, Hybrid systems, and Air-supported membranes.

Tensile Membrane Structures

Significant progress in tensile membrane structures occurred in the 20th century, especially after World War II.
Frei Paul Otto was a pioneer in tensile structures:
- The Tuwaiq Palace by Frei Otto
- The German Pavilion Grid Structure

Grid Shell

Derives strength from double curvature, similar to fabric structures.
Constructed of a grid or lattice, often made of wood or steel — similar to a garden trellis.
Pioneered by Russian engineer Vladimir Shukhov in 1896.

Materials in Shell Structures

Cable Structures
- Strand: Steel wires wound helically around a center wire in symmetrical layers.
- Rope: Multiple strands.
- High tensile breaking strength, small cross section, low weight, long fatigue life, resistance to corrosion and abrasion.

Lamella Construction

Traditionally used timber, but steel and reinforced concrete are also possible.
Patented by Friedrich Zollinger in the early 20th century.
The geometry of the curve allows for equal distances between lamellae, creating a helix on the circular cylinder surface.
Three possible types of lamellae placement on a circular cylinder surface: continual torsion, discrete torsion, and vertically placed lamellae.
The lamellae for a timber lamella vault intersect at the node.
The curve of the lamellae axis is consistent across all lamellae, but the length differs on the perimeter.
The Zollinger joint: Lamellae are spaced apart by three widths of the lamella.

Description

Explore the fascinating evolution and construction methods of shell structures from the 1920s to present. Learn about different types of shell forms, their applications, and how their unique shapes affect load stability. This quiz will test your knowledge of the history and technology behind these innovative architectural designs.