Pneumatic Structures

Pneumatic structures are flexible membranes that derive their stability from air pressure. They usually have synclastic curvature like domes, but anticlastic curvatures are possible as well. Two generic types of pneumatic structure are air supported low pressure) and air inflated (high pressure) systems. The air pressure in inflated high pressure structures is 100 to 1000 times greater than in air supported low pressure structures. Air supported structures typically have a single fabric layer...

Dulles airport terminal Washington DC 195862

Architect Era Saarinen Engineer Ammann and Whitney The Dulles international airport terminal near Washington, DC, has a cable roof supported by concrete pylons. The outward leaning pylons partly resist the cable thrust. Based on the dimensions of movable loading docks, designed by Saarinen, the pylons are spaced at 40 ft (12m) for a column-free concourse space of 150x600ft (46x183m), recently expanded, extruding the same structure. Given the slanted pylons, the suspension cables actually span...

Cable Truss

Cable trusses evolved from needs to stabilize suspension structures against wind uplift and unbalanced gravity loads, using a second set of cables with opposing curvature. The Swedish engineer Jawerth developed a cable truss with diagonal brace cables separating top support- and bottom stabilizing cables that resist wind uplift. This system was widely used in the 1960's. Lev Zetlin and other US engineers designed cable trusses with various other configurations, including lintel shapes with...

Framed Tube

Framed tubes are a variation of moment frames, wrapping the building with a wall of closely spaced columns and short spandrel beams. To place the lateral resistance system on the fa ade rather then at the interior gives it a broader base for greater stability as well as improved rotational resistance. In addition, the lateral resisting system on the fa ade allows smaller columns on the interior to carry gravity load only. Further, designing floors and roof to span the full width of a building...

World Trade Center New York 1977 demolished by terrorists 9112001

Roth Engineer Skilling, Helle, Jackson, Robertson The World Trade center of two 110-story towers and related smaller structures housed 50,000 employees and up to 80,000 visitors daily. Both towers, in diagonal juxtaposition, were vertical extrusions of square plans, with very closely spaced steel columns. Each tower had two-story mechanical spaces on top, near the bottom, and two distributed at 1 3 intervals, with elevator sky-lobbies two floors above each. Each...

Global moment and shear

Global moments help to analyze not only a beam but also truss, cable or arch. They all resist global moments by a couple F times lever arm d The force F is expressed as T (tension) and C (compression) for beam or truss, and H (horizontal reaction) for suspension cable or arch, forces are always defined by the global moment and lever arm of resisting couple. For uniform load and simple support, the maximum moment M and maximum shear V are computed as For other load or support conditions use...

Vertical Systems General Backgroui

Vertical structures have been a oh& ilerge since the ram ed towe* ci Babylon. Motivations to build tall structures include a desire to reych toward heaven to see the world from above the prestige of being tallest, and nign land costs. The tallest church tower in Ulm, Germany exemplifies the spiritual motivation. The Eiffel tower allows to see Paris from abo e. Tne vers of the Italian hill-town San Gimignano, and contemporary corporate office buildings express power and wealth the latter are...

Wind effect

A building in the path of wind causes wind pressure which in turn causes force, shear, and overturn moment at each level that must be resisted, following a load path to the foundations (wind wall pressure transfers to horizontal diaphragms, then to shear walls, finally to foundation). Wind pressure times tributary area per level causes lateral force per level. Shear per level, the sum of wind forces above, defines required resistance. Overturn moment per level is the sum of forces above times...

Info

Office building 6-story, 90'x90'x60', 30'x30' core 30' CMU walls, 8 nominal (7.625) Shear wall length L 2 x (30 - 6' doors) 48' Roof fabric canopy, 50'x50'x10', gust factor G 1.8 Interior pressure (assume conservative opening height h 60') Leeward pressure (for h 60') P 12.1 psf + 5.1 psf Average windward pressure (h 10 to 60') P (15.2+16.0+17.2+18.1+18.8+19.4 Average combined wind prossura P 17.5+17.2+5.1 Roof canopy pressure PCaniPy (12.i)(1.8j B se shear V A P 30' x (G0'-S') x 39.8 +...

CBS Tower New York 1961650

Architect Eero Saarinnen Engineer Paul Weidllnger The 38-story CBS tower Is a stark vertical extrusion of the rectangular floor plan. Columns forming a framed tube are expressed as triangular extrusions on the upper floors and diamond shaped on the ground floor. The triangular columns Include niches for mechanical ducts and pipes. The niches decrease from top to bottom with the decreasing duct sizes that run down from the mechanical room on the top floor. The decreasing niches result In...

Fuji Pavilion Expo 70 Osaka 1970

Architect Yutaka Murata Engineer Mamoru Kawaguchi The Fuji Pavilion housed an exhibit and light show of the Fuji corporation in a unique, organic form. Over a circular floor plan of 164 feet (50 meter) diameter, the pavilion featured a vaulted fabric structure composed of 16 pneumatic arched tubes. The tubes of 13 feet (4 meter) diameter were tied together by horizontal belts at 13 feet (4 meter) intervals. The tubes consisted of two vinyl fabric layers that were glued together for improved...

Wind pressure

ASCE 7 provides three methods to define wind pressure Method 1 - Simplified Design (limited to mean roof height h 60 ft 18 m ) Method 2 - Analytical Procedure (briefly described below) The Analytical Procedure includes figures and tables for wind speed, exposure, building form, roof slope, enclosure, dynamic behavior and topography. q velocity pressure G gust factor 0.85 1.5 to 2.0 Pressure coefficient 0.8 -0.7 - 0.2 to - 0.5 -1.3 to+0.4 -0.3 to-0.7 CP Cp Cp Cp Cp Cp GCp GCpi q 0.613 I Kz...

Recreation center UC Davis California

Architect Perkins & Will Engineer Leon A. Riesemberg The recreation center for the University of California at Davis holds 10,000 spectators for occasional events. Considering the low-rise context around the facility, a major design objective was to minimize the height. This was achieved by several means. The main level is 10 ft (2.7m) below grade. Landscaped earth berms, filled from the excavated soil, surround the facility to reduce its visual height. Along the building edge the roof deck...

Vertical systems

Vertical systems transfer the load of horizontal systems from roof to foundation, carrying gravity and or lateral load. Although they may resist gravity or lateral load only, most resist both, gravity load in compression, lateral load in shear. Walls are usually designed to define spaces and provide support, an appropriate solution for apartment and hotel buildings. The four systems are 1 Shear walls (apartments I hotels) 2 Cantilever (Johnson Wax tower by F L Wright) Column re-bars penetrate...

System Selection

Structural design starts with the selection of a system and material often informed by similar past projects, even if not appropriate. For example, light wood structures are common for residential building where hurricanes cause frequent destruction, though heavy concrete or masonry would resist wind load much better. A rational method is proposed with the objective to select more appropriate systems. However, since design criteria may be conflicting in some cases, selection is both art and...

Recycling hall Vienna 1981

Lang Engineer Natterer and Diettrich This recycling center features a tent-like wood structure of 560 feet (170m) diameter that soars to a height of 220 feet (67m) above ground, supported by a central concrete mast. The suspended wood roof consists of 48 radial laminated ribs that rise from outer concrete pylons with wood compression ring to the mast top. The ribs follow the funicular tension line to carry uniform roof load in pure tension, but asymmetrical loads may cause...

Concealed post cap

Concealed Beam

Concealed connections of post to beam and post to base are available, but they require greater care for proper installation and are more expensive. The alignment of bolt holes in connector and wood is essential and requires skill and experience on part of the carpenter. 1 Split ring with bolt, for twin beams, conceals all but the bolt 2 Concealed T-connector with dowels 3 Concealed L-connector with dowels 4 Concealed post base with dowels Beams need firm support attachment to prevent slippage...

Vierendeel Beam

Vierendeel Frame

Vierendeel girders resist load in combed beam action and frame action as shown on the left and right diagrams, respectively. Load causes global shear and bending which elongates the bottom in tension and shortens the top in compression. The internal reaction to global shear and bending is different in a Vierendeel compared to a beam. A beam's bending stress varies gradually over the cross-section, but global bending in a Vierendeel causes concentrated tension and compression forces in the...

Fv V Av

V shear force at section investigated Av shear area, defined as web thickness times beam depth Since this is not a rectangular beam, shear stress must be computed by the general shear formula. The maximum shear stress at the neutral axis as well as shear stress at the intersection between flange and web shear plane As will be computed. The latter gives the shear stress in the glued connection. To compare shear- and bending stress the latter is also computed. 1 Beam of L 10 ft length, with...

US Pavilion Expo 70 Osaka 1970

Architect Davis, Brody, Chermayeff, Geismar, De Harak Engineer David Geiger The US Pavilion was the first large-scale pneumatic structure in 1970 with an elliptical plan of 466x272 feet 142x83 meters yet rising only 20 feet 6 meters from a peripheral earth berm, the structure had a very low profile. This shallow curvature was possible because the translucent roof membrane was laced to a grid of diagonal cables, spaced 20x20 feet 6x6 meter that provided the primary support. The tension cables...