Jonathan Ochshorn
Room 121-B, Rand Hall
Department of Architecture
Cornell University
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ARCH 262: Building Technology, Materials & Methods
Assign #2: Sealant joints and steel framing


assigned: Oct. 22, 2001
due: Oct. 29, 2001

In class:

On one sheet of 8-1/2" x 11" paper, draw the following:

  • A sealant joint detail section cut through a vertical joint (drawn to scale: full size) showing 4"-thick cladding panel, sealant, and backup rod; and indicating the dimension of the sealant joint.

  • Sealant joint width calculations:
    • length between sealant joints (panel dimension) = 25'
    • air temperature range is from -10 to +90 degrees F.
    • movement capability of 25%
    • cladding material expands over time by 2/100 of 1% (i.e., 0.0002 x original length) due to moisture absorption
    • anticipated structural movement is negligible
    • expect deviations in the panel alignment (construction tolerance) of 1/8"
    • For preliminary sizing, use: W = (100/X)[eL(DT) + M] + t; where:
      • W = required width of sealant joint;
      • X = % movement capability of sealant, i.e., 25;
      • e = coefficient of expansion of building "skin" material to be sealed = 0.0000036 (see below for examples);
      • DT = annual range between extreme temperatures (assume 130 degrees F if not known; in this case, use 100 degrees F);
      • L = length of cladding panels between joints (i.e., joint spacing) = 25'
      • M = anticipated nonthermal movement due to deflection, creep, moisture movement;
      • t = construction tolerance.

      Note: it is important that units are consistent. Convert all dimensions to inch units.

Model-building Assignment (groups of 4 or less OK):

Build a cardboard/chipboard model of a section of a steel-framed building showing corrugated steel deck with concrete fill, finish floor material, column enclosures, steel columns, beams, and girders, suspended ceiling, cladding panels with vertical sealant joint, and mechanical (fan-coil) unit.

  • Build model at scale of 1" = 1'-0"
  • Assume 8"x8" steel column with 1' square column enclosure.
  • Assume 18" - 24" deep steel beams and girders with 6" flange width.
  • Indicate connections between steel elements as welded or bolted.
  • Show connection of cladding panels to structure.
  • Show suspended ceiling as rectangular or square panels hung from corrugated steel deck on a grid-like metal suspension system.
  • It is not necessary to show fireproofing materials.


Coefficients of Expansion of Common Building Materials (in/in/degree F)

Wood
  • Douglas Fir (parallel to grain) 0.0000021
  • Douglas Fir (perp. to grain) 0.000032
  • Pine (parallel to grain) 0.0000030
  • Pine (perp. to grain) 0.000019
Masonry
  • Limestone 0.0000044
  • Granite 0.0000047
  • Marble 0.0000073
  • Brick (average) 0.0000036
  • Concrete Masonry Units 0.0000052
Concrete
  • Normal weight concrete 0.0000055
Metals
  • Steel 0.0000065
  • Stainless Steel (18-8) 0.0000099
  • Aluminum 0.0000128
  • Copper 0.0000093
Finishes
  • Gypsum board 0.000009
  • Gypsum plaster, sand 0.000007
  • Glass 0.000005
  • Acrylic glazing 0.000041
  • Polycarbonate glazing 0.000044
  • Polyethylene 0.000085
  • PVC (vinyl) 0.000040

last updated: 20 Oct. 2001
Copyright 2001 J. Ochshorn. All rights reserved. Republishing material on this web site, whether in print or on another web site, in whole or in part, is not permitted without advance permission of the author.