Learning from Failure in the Design Process

Experimenting with Materials

Lisa Huang

• Publisher: Routledge
• Year: 2020
• ISBN:
  9781317419747
• Edition: 1
• Topic: Architecture
• Subtopic: Architecture Methods & Materials

Learning from Failure in the Design Process shows you that design work builds on lessons learned from failures to help you relax your fear of making mistakes, so that you're not paralyzed when faced with a task outside of your comfort zone.

Working hands-on with building materials, such as concrete, sheet metal, and fabric, you will understand behaviors, processes, methods of assembly, and ways to evaluate your failures to achieve positive results. Through material and assembly strategies of stretching, casting, carving, and stacking, this book uncovers the issues, problems, and failures confronted in student material experiments and examines built projects that addressed these issues with innovative and intelligent strategies.

Highlighting numerous professional practice case studies with over 250 color images, this book will be ideal for students interested in materials and methods, and students of architecture in design studios.

Chapter 1

Why Stretch?

1.1 What Can We Stretch?

Material Considerations

When we think of stretched materials in space-making, the most basic typology that emerges is the tent. It is one of the earliest primitive structures used for weather protection and domestic enclosures. Nomadic peoples used animal hides or fabric held over a framework that could be easily assembled and disassembled as they moved from one location to another. Fabrics were draped, stretched, and held in tension to create a lightweight temporary shelter (Figure 1.1).

FIGURE 1.1 Nomadic tents using flexible materials. Photo: Richard Throssell.

Why would we consider using a stretched assembly as a design option? In modern times, we would utilize stretched assemblies for essentially the same reasons. If we need a quick temporary construction, stretching materials is efficient in covering large areas with a single membrane material. Its potential simplicity in construction enables a stretched assembly to be economical and lightweight. Stretching requires a thin pliant material and shaping the material is dependent on the structural framework. The material’s thinness can be both ethereal and vulnerable. Durability is the biggest concern for stretched assemblies. We need to design to resist tearing in the pliant material. The panel shape, installation strategy, and framework connections are critical considerations to control the material’s behavior in a taut construction.

Typical Stretching Materials and Components

In our discussion of stretched materials, we will consider the scale of the building and the scale of the component. At both these scales, a supple fabric or plastic membrane becomes a useful architectural material when something rigid – a structure or framework – gives it distinguishable form. The stretched material has no rigidity until it is held in tension. At the component scale, stiff materials like metals and glass can also be stretched and deformed to create three-dimensional panels.

At the building scale, we would typically use a lightweight and thin fabric or plastic membrane as a single material component to span long distances. The floppy material needs to be pulled taut in order to create a stable structural form. Precise cuts and patterns for the material minimize wrinkles in the stretched assembly. As with most building components, stretched materials come in limited dimensions, so we weld or sew together membranes to create larger components. Most stretched materials at the building scale take advantage of translucency and light transmitting characteristics of the membrane. However, seams are visible from the interior during the day and visible from the exterior when illuminated at night, so we also must consider the design of the seaming pattern.

In early experiments with membranes, Frei Otto stretched flexible materials to explore the potential of the membrane in an assembly. Otto saw this flexibility as a strength not a weakness. ¹ A flexible membrane allowed a pure expression of structural forces and produced a new language of form and assembly to architectural structures.

Stretched structures are commonly used for temporary open-air pavilions at expositions to test the flexible material’s potential. The development and evolution of tensile structures transform stretched materials into airtight and watertight assemblies. Permanent buildings using stretched membranes are monolithic, but they also reflect a temporary and ephemeral appearance.

Coated fabrics as stretched architectural membranes include woven fiberglass, polyester, nylon, or polyethylene. Durability of the membrane is the primary concern, so the sturdy fabrics and plastics used for sails were precursors for building components. These woven membranes are coated with PVC, Teflon (PTFE), or silicone to help increase longevity and easy maintenance. In addition, the coating provides an airtight and water-resistant UV protectant for the membrane. It needs to withstand wear and tear from temperature changes, weather impacts, and UV exposure. Woven textile materials may also have inherent elasticity and offer a range of opacities and translucencies. Stretched fabric options vary in flexibility, life span, code compliance, light transmission, tear strength, and durability. The choice of fabric depends on its application and the architectural characteristics needed for the membrane. Material costs vary and the combination of fabric and coating influences its suitability for an assembly.

Coated fabrics can be singular components or stitched together into a monolithic panel. The maximum dimensions of the fabric depend on the manufacturing equipment and production processes. The width of a fabric panel is usually the limiting factor.

In order to produce a monolithic membrane, the fabric components are joined together by welding or sewing. We must consider the pattern and cut of the fabric so that it coordinates with the supporting structure. The fabric membrane also needs its own internal structure that pulls taut without jeopardizing the integrity of the membrane and seams. But with elastic fabric, we should also be aware of creep and sagging with time. Fabric panels will need reinforcement on its edges or corners and then also intermittent support to compensate for sagging.

If the membrane is composed of fabric panels, the cutting, welding, or sewing together of the components is critical to ensure balance and stability when the membrane is pulled taut. In Skidmore, Owings and Merrill’s Hajj Terminal at the King Abdulaziz International Airport, fiberglass fabric shades the facilities and spans a large area (Figure 1.2). The use of fabric in a permanent building requires precision to ensure balance between the structure and the membrane. During construction, one of the fiberglass fabric membranes was cut incorrectly, so when the membrane panel was installed, it put structural stresses in wrong places. As a result of the membrane’s tensile limitations, the fabric ripped in four places. ² Any imbalance of structural forces on the fabric can cause problems for the assembly.

FIGURE 1.2 Hajj Airport in Jeddah, Skidmore, Owings & Merrill Photo: UR-SDV [GFDL (http://www.gnu.org/copyleft/fdl.html) or GFDL (http://www.gnu.org/copyleft/fdl.html)].

Fabric panel requires reinforced hems and grommets at edges and openings to protect fabric from tearing when it’s fastened to the structural anchors and supports. When illuminated at night, the fabric roof of the Denver International Airport by Fentress Architects reveals the hems and seams that unify the larger fabric membrane (Figure 1.3). The hems negotiate between the fabric and the structural masts. The fabric drapes from each peak revealing the orientation and structure of the seams. This seam pattern may seem like a small detail in the building, but it impacts our visual experience of the building and our understanding of the construction assembly.

FIGURE 1.3 Denver International Airport, Fentress Architects. Photograph provided courtesy of Denver International Airport.

The use of plastic sheets and Ethylene Tetrafluoroethylene (ETFE) foils in architectural constructions was originally developed by Dupont. Starting in the 1990s, these materials were introduced in European buildings. ETFE is a plastic polymer that is extruded into thin flexible sheets that resist deterioration and are recyclable. The thin plastic membrane is very elastic and transmits light. It is an almost completely transparent material that is available in a range of colors and opacities. ETFE foil does not discolor or weaken structurally over time, so it withstands ultraviolet damage. To achieve solar glare protection, the foil surface can be tinted or overlaid with different surface patterns.

ETFE foils utilize different assembly strategies compared to fabrics. The thin foils are stretched by a cable net system or within a metal frame (typically aluminum) which is then inserted into a larger structure. Each panel can have a single layer or be multi-layered with two to five foils. The use of a metal frame supports the ETFE panel when it’s inflated with air. The inflated cushion provides thermal insulation and its thermal properties in...

Table of contents

• Cover
• Endorsements
• Half-Title
• Title
• Copyright
• Dedication
• Contents
• List of Figures
• Acknowledgements
• Introduction
• Chapter 1. Why Stretch?
• Chapter 2. Why Cast?
• Chapter 3. Why Carve?
• Chapter 4. Why Stack?
• Bibliography
• Index