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‘Structural Concepts’ Part Two

Constructing Environments Maxwell Bracher 636699


Queen’s College Extension Using information gathered in week 5, a 1:20 Scale model was produced. Materials: 3mm box board Imm aluminium wire 3mm balsa wood Drawing pins Masking tape

Right: box board walls represent reinforced pre-cast concrete walls, the main structural feature of the building. NB: only a portion of the extension was modelled.

Constructing Environments Maxwell Bracher 636699


STRUCTURAL CONCEPTS PART ONE: What did we learn? Primary structure: Reinforced pre-cast concrete panels (box board) Roof beams - 150 x 75 PFC (balsa wood) Secondary structure: Rafters at 900 centres (balsa wood) R1: 190 x 45 Pine R2: 140 x 45 Pine R3: 170 x 45 Pine Horizontal bracing: steel rods (aluminium wire)

Constructing Environments Maxwell Bracher 636699

Reinforced pre-cast concrete panels Roof beams Rafters

Steel rod horizontal bracing


Above: Cross section of model including beams, rafters, walls, horizontal bracing. The verandah uses a cantilever to support itself. Horizontal bracing assures the rectangular structure does not warp. The adjacent reinforced pre-cast concrete wall directs the load in compression to the footings. Roof beams support the exterior croof cladding provide the primary structural support to the building Beneath, rafters support the ceiling. This is an outdated and uncommon method in public buildings.

Constructing Environments Maxwell Bracher 636699


Top: securing of roof beams (masking tape) and precast concrete walls (drawing pin)

Reinforced pre-cast concrete walls carry the vertical load in compression, to the footings and foundation. Roof beams are affixed directly to the pre-cast walls, as are rafters. The cladding is supported in copression, parallel to the grain. Tensile forces affect the bottom of the beam as it warps minutely. The verandah uses a cantilever to spread the load in tension. Horizontal steel bracing ensures the building remains true to its form. They carry the load in tension.

Constructing Environments Maxwell Bracher 636699


Above: Queen’s College extension in plan view. Model made to scale 1:20.

BIBLIOGRAPHY Ching, F.D.K. 2008, “Rafter Framing” in Building Construction Illustrated, 1st edn, John Wiley & Sons, Inc., Hoboken, New Jersey, pp. 6.17.

Constructing Environments Maxwell Bracher 636699


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