The occupants, alerted by the attacks on WTC 1, WTC 2, and the Pentagon, began evacuating promptly. Evacuation of the building took just over an hour, and the process was complete before the collapse of the first WTC tower . No emergency responders were harmed in the collapse of WTC 7 because the decision to abandon all efforts to save WTC 7 was made nearly three hours before the building fell.
- Of thermite, or more, could have been carried into WTC 7 and placed around columns without being detected, either prior to Sept. 11 or during that day.
- Completed in 1981, its design, by Der Scutt of Swanke Hayden Connell solved the swooping onrush pedestrian problem by truncating its slant above the street-level retail spaces.
- The SFRM in WTC 7 was modeled as undamaged except in the southwest region of the building where there was debris impact damage2.
Utilizes distinct systems (e.g. all-steel, all-concrete, all-timber), one on top of the other. For example, a Steel Over Concrete indicates an all-steel structural system located on top of an all-concrete structural system, with the opposite true of Concrete Over Steel. WTC 7’s designers intended its stairwells to evacuate nearly 14,000 occupants, anticipated at the time to be the maximum occupancy of the building. Though the stairwell’s capacity was overestimated, it was adequate for evacuating the building’s actual maximum occupancy of 8,000, and more than adequate to evacuate the approximately 4,000 occupants who were in the building on Sept. 11. In general, much less evidence existed for WTC 7 than for the two WTC towers.
Given the fires that were observed that day, and the demonstrated structural response to the fires, NIST does not believe that thermite was used to fail any columns in WTC 7. For the building to have been prepared for intentional demolition, walls and/or column enclosures and fireproofing would have to be removed and replaced without being detected. Preparing a column includes steps such as cutting sections with torches, which produces noxious and odorous fumes. Intentional demolition usually requires applying explosive charges to most, if not all, interior columns, not just one or a limited set of columns in a building.
These validated computer models produced a collapse sequence that was confirmed by observations of what actually occurred. This analysis showed that the 40 percent longer descent time—compared to the 3.9 second free fall time—was due primarily to Stage 1, which corresponded to the buckling of the exterior columns in the lower stories of the north face. During Stage 2, the north face descended essentially in free fall, indicating negligible support from the structure below. This is consistent with the structural analysis model which showed the exterior columns buckling and losing their capacity to support the loads from the structure above. In Stage 3, the acceleration decreased as the upper portion of the north face encountered increased resistance from the collapsed structure and the debris pile below.
The sections of the steel bracing in front of the windows are coated with black aluminum. The CTBUH lists a project manager when a specific firm has been commissioned to oversee this aspect of a tall building’s design/construction. When the project management efforts are handled by the developer, main contract, or architect, this field will be omitted.
d Floor: Types
Explicit adoption of the “structural frame” approach to fire resistance ratings that requires all members of the primary structural frame to have the higher fire resistance rating commonly required for columns. The primary structural frame includes the columns, other structural members including the girders, beams, trusses, and spandrels having direct connections to the columns, and bracing members designed to carry gravity loads. Composite floor systems whose shear studs could fail due to differential thermal expansion (i.e., heat-induced expansion of material at different rates in different directions). Several factors contributed to the outcome of no loss of life-or serious injuries-in WTC 7. The building had only half the number of occupants on a typical day-with approximately 4,000 occupants-at the times the airplanes struck the towers.
The second floor and mezzanine is still marketed as a trading floor as of 2021. The fourth floor contains a two-story mechanical space, which is hidden on the exterior. Both the main vertical/lateral structural elements and the floor spanning systems are constructed from timber. An all-timber structure may include the use of localized non-timber connections between timber elements. Note that a building of timber construction with a floor system of concrete planks or concrete slab on top of timber beams is still considered an “all-timber” structure as the concrete elements are not acting as the primary structure. The water main served as both the primary and backup source of water for the sprinkler system in the lower 20 floors.
Solow sued Avon in 1997, claiming it had failed to restore its offices in the building to their original condition. Solow, represented by David Boies, also sued JPMorgan Chase for not restoring its offices after moving out. In that case, the judge ruled against Solow, finding that JPMorgan had indeed tried to restore its space but that Solow had “substantially interfered” with JPMorgan’s ability to do so. R. Grace Company in 1999 for spraying asbestos on the building in the early 1970s, despite marketing the asbestos as a safe product.
t Floor: Types
The 58th Street side of the plaza contains Moonbird, a sculpture by Joan Miró. The sculpture, originally commissioned in 1966, is 14 feet (4.3 m) tall and made of bronze. Solow installed Moonbird in 1994, saying that “it is one of my very favorite sculptures”; he already had a print of the same work. Before Moonbird was installed, the 58th Street side of the plaza had a 12-foot (3.7 m) “mobile” by Alexander Calder.
Overall, the tower has a gross floor area of about 1,400,000 square feet , with 33 elevators in total. Both the main vertical/lateral structural elements and the floor spanning systems are constructed from steel. Note that a building of steel construction with a floor system of concrete planks or concrete slab on top of steel beams is still considered an “all-steel” structure as the concrete elements are not acting as the primary structure. In response to comments from the building community, NIST conducted an additional computer analysis. The investigation team concluded that the column’s failure under any circumstance would have initiated the destructive sequence of events.
Questions and Answers about the NIST WTC 7 Investigation
If you’re in a betting mood, be sure to check out our game tables, including poker and card. The corporate offices of Avis Budget Group are also located in the building. We have a massive inventory, and are able to custom order countless options so if you’re unable to find what you need, just ask. Our friendly, knowledgeable staff loves to lend a helping hand and can answer any questions you might have about installing and using our products.
Early in the investigation, a decision was made to complete studies of the two tower collapses before fully proceeding on the WTC 7 investigation. A major technical conference on the draft reports on WTC 1 and WTC 2 occurred on Sept. 13-15, 2005. The time between the technical conference on the WTC towers report and the issuance of this draft WTC 7 report is approximately three years, comparable to the length of a typical investigation of an aircraft crash. Analysis of the WTC steel for the elements in thermite/thermate would not necessarily have been conclusive. The metal compounds also would have been present in the construction materials making up the WTC buildings, and sulfur is present in the gypsum wallboard used for interior partitions. Better thermal insulation (i.e., reduced conductivity and/or increased thickness) to limit heating of structural steel and minimize both thermal expansion and weakening effects.
Rec Room Flooring
The north and south facades of the Solow tower project slightly from the building’s edges and are extraordinarily sensuous because of the very fine detailing of the window gaskets. One of the most controversial buildings in midtown and also one of the most successful midtown real estate ventures, 9 West 57th Street is largely responsible for the subsequent redevelopment of the Plaza District into the city’s most prestigious office precinct. The General Motors Building had led the way, of course, when it was erected in 1968, but it merely ruined the elegant ambiance of Grand Army Plaza by razing the Savoy Plaza Hotel.
Bunshaft, who also designed Lever House on Park Avenue, was not content that the gutter alone would alleviate pedestrian anxiety and he and Solow had the brainstorm to place a very large, bright red metal sculpture of the number “9” in front of the building. The sculpture is not quite effective as Isamu Noguchi’s brilliant red cube in front of the Marine Midland Plaza tower at 120 Broadway, but it is nice, amusing and diverting. With the late 1990s and early 2000s came a series of lawsuits against tenants.
Nationsbanc Montgomery had 350,000 square feet in 9 West 57th Street by December 1998, more than any other tenant in the building. Despite the departures, new tenants at the Solow Building continued to sign leases at premium rates. Concurrently, Solow had hired Hardy Holzman Pfeiffer to redesign the unused retail space in the basement. Two of the escalators were removed to make way for the entrance to the Brasserie 8 1/2 restaurant. The surrounding stretch of 57th Street was part of an artistic hub during the late 19th and early 20th centuries. The southern part of the site was occupied by the Pace Gallery, which operated there from 1963 to 1968.
The Continental Illinois debit memo at 520 Madison Avenue between 53rd and 54th Streets has a partially slanted form and is not freestanding but occupies the full Madison Avenue blockfront. Completed in 1981, its design, by Der Scutt of Swanke Hayden Connell solved the swooping onrush pedestrian problem by truncating its slant above the street-level retail spaces. For those impressed with the slickness of the sloping facade, there are legions more, however, that were outraged at the building’s “violation” of the traditional streetwall.
Bunshaft instead decided to use curved facades on the north and south elevations, avoiding the need for rectangular setbacks. Even without the structural damage, WTC 7 would have collapsed from the fires that the debris initiated. The growth and spread of the lower-floor fires due to the loss of water supply to the sprinklers from the city mains was enough to initiate the collapse of the entire building due to buckling of a critical column in the northeast region of the building.