Tensile Fabric Structures: Design, Analysis, and Construction

Tensile fabric structures are part of a unique technology that gives designers, architects, and engineers the ability to experiment with form and create exciting solutions to conventional design problems. The history of tent forms and tent technology, including air structures, cable nets, and movable and retractable roofs, is presented.

The overall design and construction process of tensioned fabric structures is discussed and the role of each participant in the project, from inception through completion, is described. Concept development and preliminary design; contract documents; patterning and detailing; fabrication and erection; and inspection and maintenance are covered.

Architectural fabric technology has advanced and more options are available for tensile fabric structures. Descriptions of fibers, yarns, weaves, and coatings used most commonly are provided, including polyester, glass, expanded PTFE, and aramid fibers; polyvinylchloride (PVC), PTFE (Teflon), and silicone coatings; and ETFE films. The combination of these various materials influences the fire resistance, translucency, lifespan, tensile strength, stretch and dimensional stability, workability, and environmental qualities and sustainability of the fabrics.

Tensile membrane structures are subject to the same climatic, environmental, and service loads as other structures with the same location, exposure, and use. Design loads should be determined from the building code in the structure's jurisdiction. Dead loads, live loads, wind loads, snow loads, rain loads, and seismic loads are discussed.

The range of possible forms in tensile fabric structures is extensive but not free-form and the structures must conform to the physical principals which govern their behavior. Basic design principles, structural forms, models, and methods of analysis are presented.

Materials used in tensile membrane structures and their behaviors under applied loads are often outside the realm typically considered for building structures. Behavior characteristics and design parameters, which are critical to understanding and evaluating tensile membranes and their system components under applied loads, such as wind and snow, are considered in this chapter.

Tensile fabric structure connections transfer working stresses to the cables or other reinforcing materials and then into the supporting structure. Design forces in cables and steel may be high, and connections must be designed to provide a path for these loads to flow to grade. The fabric joints, cable saddles, mast tops and bases, and tensioning mechanisms must satisfy a range of parameters that make their design uniquely challenging. These include: load transfer; displacement and rotation; adjustability; assembly; durability; and aesthetic considerations.

Non-structural performance considerations for all types of tensile membrane structures are presented. These include: fire safety; lighting and energy use; acoustics; aesthetics; material and labor availability; cost issues; and maintenance, durability, and inspection.

Fabrication and construction of tensile fabric structures begins with patterning and the conversion of the 3D design to a 2D pattern. Additional fabrication considerations discussed include variations in fabric strength, fabric-to-ring connections, compensation, system adjustability, efficiencies, new fabric options, and the use of mock-ups and pre-fitting. Installation steps of packaging, handling, pre-tensioning, and finishing conclude the chapter.

A brief review of the wind tunnel testing process for tensile fabric structures.