Thin Shell Concrete Design and Construction
Jessica Mandrick E90 Project Proposal Swarthmore College Department of Engineering
Thin Shell Concrete Structure Design and Construction
1
1
Introduction
The ACI code defines a thin shell as a: “Three-dimensional spatial structure made
up of one or more curved slabs or folded plates whose thicknesses are small compared to their other dimensions. Thin shells are characterized by their three-dimensional loadcarrying behavior, which is determined by the geometry of their forms, by the manner in which they are supported, and by the nature of the applied load.” Concrete shell structures are able to span large distances with a minimal amount of material. An arch, spanning tens of feet, can be mere inches thick. In maintaining this economy of material, these forms have a light, aesthetic, sculptural appeal. I am planning on designing and constructing a thin shell concrete structure for my senior design project. The structure constructed would be at a maximum size, ten feet by ten feet, which may be scaled down if necessary during the design phase. I will be working on this project with Rebecca Burrow who is assisting as part of a directed reading arranged through Professor Siddiqui. Rebecca is currently abroad. Thin shell concrete structures are pure compression structures formed from inverse catenary shapes. Catenary shapes are those taken by string or fabric when allowed to hang freely under their own weight. As string can bear no compression, the free hanging form is in pure tension. The inverse of this form is a pure compression structure. Pure compression is ideal for concrete as concrete has high compressive strength and very low tensile strength. These shapes maximize the effectiveness of concrete, allowing it to form thin light spans.
2
2.1
Project Plan
Structural Design and Analysis of Thin Shell Structures A structural design of the thin-shelled concrete structure will be computed using
catenary and geometrical shape equations. The
Thin Shell Concrete Structure Design and Construction
1
1
Introduction
The ACI code defines a thin shell as a: “Three-dimensional spatial structure made
up of one or more curved slabs or folded plates whose thicknesses are small compared to their other dimensions. Thin shells are characterized by their three-dimensional loadcarrying behavior, which is determined by the geometry of their forms, by the manner in which they are supported, and by the nature of the applied load.” Concrete shell structures are able to span large distances with a minimal amount of material. An arch, spanning tens of feet, can be mere inches thick. In maintaining this economy of material, these forms have a light, aesthetic, sculptural appeal. I am planning on designing and constructing a thin shell concrete structure for my senior design project. The structure constructed would be at a maximum size, ten feet by ten feet, which may be scaled down if necessary during the design phase. I will be working on this project with Rebecca Burrow who is assisting as part of a directed reading arranged through Professor Siddiqui. Rebecca is currently abroad. Thin shell concrete structures are pure compression structures formed from inverse catenary shapes. Catenary shapes are those taken by string or fabric when allowed to hang freely under their own weight. As string can bear no compression, the free hanging form is in pure tension. The inverse of this form is a pure compression structure. Pure compression is ideal for concrete as concrete has high compressive strength and very low tensile strength. These shapes maximize the effectiveness of concrete, allowing it to form thin light spans.
2
2.1
Project Plan
Structural Design and Analysis of Thin Shell Structures A structural design of the thin-shelled concrete structure will be computed using
catenary and geometrical shape equations. The