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911 Title: World Trade Center: Building Facts Adopted from a thesis titled: The World Trade Center Disaster: Analysis and Recommendations by Jeremy Kirk 2.0 Tower Construction and History Architectural, engineering design: Started 1960's Construction started -------------- 1965 Construction completed ------------ 1972 Structural engineer of record ----- Leslie E. Robertson & Associates Architect - - - - - - - - - - - - - Minoru Yamasaki Construction type ----------------- "Frame-tube" design. Exterior plan size ---------------- 207 foot square sides Innovations: - two-way truss framed floors, - prefabricated column and spandrel panels, - spray-applied fireproofing Steel grades - - - - - - - - - - - - 14 Typical steel uses: Beams, columns, column sections, floor trusses and floor deck Steel yield strenghts ----------- 36 to 100 ksi Perimeter tube structure: - 59 columns per side - Columns prefabricated into panels 3 columns wide and three stories high Perimeter columns built up from steel plates welded together approximately 14" square, Spaced 40" on center The plate steel varied from 1/4" thick near the top of the towers to 2" thick at the base. columns joined by 52" deep spandrel plates at each floor level Bolted splice plates occurred between the floor levels at every third story. Exterior finish: - Aluminum sheathing wrapped the exterior of the columns; this created the desired architectural finish. Tower cores: - Central core 87' x 137' - Design to carry about 60% of the total gravity loads but not lateral loads - On lower floors core columns were built-up box columns 12" x 52", made of plates up to 7" thick. - On upper floors columns changed to wide flange shapes at staggered intervals. Floors: - Floor slab (outside of the core) 4" of lightweight concrete poured on corrugated steel decking Concrete and steel decking integrated into steel trusses - Steel trusses used to create two-way spans in the four corners of the tower - One-way spans elsewhere - Longest spans about 60' Truss assembly - Pre-assembled in modules 20' wide. - Trusses set in pairs at 6'-8" on center (locating them at alternating exterior columns) Truss mounting to perimeter tube structure Seats made out of 'angle iron' connected the ends of the trusses to the spandrels Each angle supported the ends of two trusses. The bottom angles of each truss top chord were attached to the seat angle by means of one 5/8" diameter bolt. The seat angle is welded to two stand-off plates, which were welded to the spandrel beam. A gusset plate connected the top of the truss top chord to the spandrel. The bottom chords of each pair of trusses were connected to the spandrel with a visco-elastic damper, a feature which helped limit sway in the towers. The dampers had a slip capacity of 5 kips. At the core end of each truss, a seat was formed from one horizontal plate and two vertical stiffeners, which were attached to channels running continuously along the core columns. Core floors: - Floor slab was 5.75" normal-weight concrete on metal deck. - Supporting structure was wide flange steel beams - wide flange steel beams then acted compositely with the slab, - wide flange steel beams rigidly connected to the columns Fire proofing, Initial design: - Sray applied fire proofing (SFRM for "sprayed fire resistant material") on all structural members History - Towers not required to meet the New York City building code as the towers were under the jurisdiction of the Port Authority of New York and New Jersey, PANYNJ), - designers intended to meet or exceed all pertinent code requirements. - Code required all columns to have a three hour fire rating, - Floor members to have a two hour rating. - The as-built thickness for the fireproofing on the floor trusses was 0.5" Port Authority was in the process of upgrading the fireproofing in the towers - New, more restrictive standards called for 1.5" - All floors in the damaged zone of WTC 1 had been upgraded to the new thickness of 1.5". - Of the affected floors of WTC 2 only floor 78 had received the upgraded fireproofing. Hat Truss - Top four stories of each tower (floors 107-110) formed a "hat-truss", - Hat Truss helped restrict lateral sway. - Hat Truss on WTC also supported the large broadcast antenna structure.
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#1. To: _Jim (#0)
Hey find us a link to a blueprint. Thanks for posting.
I'll see what I can find here at the ... uh ... office.
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