Prefabrication experiments - 265 - Connectors - 06 - Roger Halle's building system

Identified as a research architect, Roger Halle (1919-1993) was an American inventor / designer / architect who spent his career experimenting with building systems and components aimed at simplifying onsite construction and reduce construction costs. He patented connectors, processes and pieces, which all lead to the foundation of the Halle Building System Company. Based on the ideal of industrializing building, the heart of the Halle building system was a connector devised to streamline and normalize a three-axis assembly between vertical columns and horizontal beams. He conceived his connector as part of a catalogue of steel ready-made components leveraged toward a large number and variety of buildings. The open frame steel skeletal structure would also make the integration of other building systems straightforward with the use of open web joists for floors. The open joists’ web shapes a network of spaces for passing ductwork, plumbing and wiring. All standard structural components could be manufactured to stock and specified according to guidelines and design tables limiting complex engineering tasks. This would further streamline the building process. 

 

 Paralleling many of its contemporaneous experiments, the overall building system was dimensionally coordinated and arranged around a 40-inch modular grid matrix, which would define spans and all connecting components. The connector is a steel unit shaped with consoles to support horizontal joists and male extensions to connect vertical column sections. Once inserted into the lower and higher columns, bolting the joint ensures structural continuity. The joists are also fashioned with a fused seat that sits over the connector’s console to easily and precisely bolt it in place. Apertures on the unit’s two opposing directions optimizes its weight to stress ratio and also makes it possible to pass systems (wires or pipes) through the joint; making it a veritable cable chase. This simple matrix was designed to reduce the number of pieces required for a simple post and beam skeleton. Considering integration of all building systems, Halle also proposed a u-shaped lower and upper chord for the joists making it easier to attach floor or ceiling panels.  This universal connector designed for assembly could also in today’s jargon be designed for disassembly facilitating long-term adjustments and evolution. 

The Halle Joint

Prefabrication experiments - 264 - Connectors - 05 - Patch Project

Designing and creating underwrite making by federating a great deal of knowledge imparted by professional education, training or by specific guidelines and normalisation. The democratization of timber construction, in particular, communicates this collective sharing of artisans’ methods, cutting standards and normalized joinery. Industrialization substituted the artisan with task division, placed knowledge in the hands of engineers and manufacturers and made specialized components or pieces the core of modern building culture. The ensuing normalisation significantly diversified production. A quick walk in any hardware store in the connector aisle presents the innumerable amount of ready-made hangers, straps, fasteners and couplings for putting two pieces of timber together. While removing the specialized artisan, these factory-made fasteners also make it possible for untrained users build their own structures with the confidence that the connector is robust and sturdy enough for its intended use. The connector fashioned with the correct dimensions, thickness and angles simplify joinery and have long contributed to the D-I-Y building and the recent hacking culture. Producing a connector that is both simple to use and understand in a sense elevates its designer’s status to craftsman as the device’s use in multiple structures showcases inherited purposes and potentials for customizable assemblies.

 

Patch Project by the Polish design studio Beza Projekt continues the tradition of the Do- it-yourself well-designed connector by streamlining making and providing anyone the means to craft their own projects. Patch Project showcases the designer at once as the developer and the artisan for crowd sourced productions. A series of bright red plates folded and shaped into different configurations offer a number of varying ways of joining standardized pieces of timber. Analogous to Ken Isaac’s modular matrix structures developed in the 1970s, the connectors are the basis of a perceived variety established on predetermined options for geometric adaptations. In Patch Project the connectors are meant to symbolize a type of conceptual patchwork arrangement with encoded yet unspecified directions. Each timber piece can be placed at right angles or at predetermined angles for both ordered and chaotic arrangements. This type of connector is a special architectural object as it imparts building knowledge and makes construction a fundamentally social process connecting design, craft and people.

Patch Project connectors' series

Prefabrication experiments - 263 - Connectors - 04 - Geodesic dome hubs

First explored in the 1940s, every generation of educators, architects, designers and DIYers seems to rediscover the pleasure and structural enlightenment that comes from assembling a geodesic dome. Associated with R. Buckminster Fuller and his Fuller Research Foundation, the geodesic dome is a segmented reticulated framework, which forms a spherical shape. Established from the study of an icosahedron, a platonic solid of twenty identical equilateral triangle faces, points (vertices) are extended outward toward a great circle according to a predetermined number of divisions or segments. This division of each composing triangular face is the dome’s frequency or its capacity to approach the sphere’s radius as closely (greater frequency) or as loosely (lower frequency) as desired. 

 

It seems at first glance relatively simple as the segments follow a repeating pattern. This is the case for the equilateral triangles, however each segment and angular deformation within the triangle are dimensionally nuanced and modulated as they spread toward the curve. The hubs, intersections or connector points are fundamental to the dome’s assembly as they define at once the angle and the number of struts splitting from each vertex. Connectors are the secret to the domes’ perceived simplicity. Along with their numerical and mathematical importance to the domes’ geometry, structurally the hubs react to both tensile (parallel, hoop) and compressive (meridional, arch) stresses. Composing triangles and their connection points push and pull against one another, under uniform loading. 

 

Sonostar connectors, is one of many companies offering options to construct a dome based on a configuration that is determined on-line through the company’s website. A construction kit of parts from made to stock pieces and connectors is then delivered to any context. Connectors include five or six appendages regardless of the dome’s frequency as combining the triangles forms a skeletal network of hexagons (6 points) or pentagons (5 points). Geodesic domes are experimental structures, rarely massively applied, that garner fascination through the satisfaction that comes with seeing geometry and structural assembly in action. Sonostar’s dome kits propose standard PVC piping for the struts, which makes for a simple female to male fastened or bonded connection.

Two connector scales (standard and mega hub) form the company website

Prefabrication experiments - 262 - Connectors - 03 - Charles Attwood, Unistrut and Moduspan

The successful application of steel in building structures has paralleled and entrenched standardization. The normalization of profiles, shapes, pieces and fittings was rigorously controlled from the factory to the field. Pre-established and calculated connections facilitated steel’s democratization by sharing validated models for engineering, architectural design and construction. The steel building construction sector developed an open exchange of fabrication, specifications and assembly standards. Further, this knowledge was certified in the factory and by academia supporting the use of published computations and theory. Industrialists imagined all manner of skeletal and reticulated building structures from the cataloguing of parts and assemblies. 

 

One of the most enduring systems, the Unistrut building component system was based on both standardized shapes and simple bolted joinery for securing pieces together in a plurality of directions and arrangements.  Charles Attwood created Unistrut in the early 1920s for mounting electrical components in equipment, racking or scaffolding applications. A spring-activated nut that is pushed and glided in a u-shaped profile is the central proprietary element. The nut is positioned along struts at any point and makes multiple arrangements possible. Expanded further, the Unistrut system went from a simple strut and tie structure to a reticulated 3d space frame with the addition and invention of a mulit-directional hub connector. 

 

Known as Moduspan, a subsidiary system of the Unistrut corporation, it employed a simple plate-based joining system for fastening a structural framework of upper, lower and diagonal chord members. The horizontal and vertical plates clipped together maintain an x,y,z coordinated system for coordinating anchor points. The standard Unistrut channels 40mm x 400mm could be bolted to the plates at different locations to vary length, angle and overall geometry. Applicable to floor and roof construction, as an open treillis, a type of three-dimensional truss, it was just one of many space frame prototypes (Mero, Triodetics, Abstracta) invented in the second half of the 20th century. Attwood marketed the no welding or drilling, flexible and adaptable business model from the early 1900s and it is still applied today. Moreover, the Unistrut and Moduspan design for assembly principle could today be reversed and speak to a design for disassembly model making all components part of systems with multiple service lives.

Moduspan connector