While the 93-story Vista Tower is now well above ground along the south bank of the Chicago River in Lakeshore East, the design of the upcoming luxury hotel/condo development is still being refined. According to Chicago Architecture Blog, the Magellan-Dalian Wanda Group joint venture will see the residential space on the tower’s 83rd floor replaced with an open-air “blow-through.”
Designed to offer relief from high wind forces, the void will span the widest part of the tower’s highest “frustum” segment. The blog’s author specifically cites language from the Chicago’s Department of Planning and Development, which pointed to occupant comfort as the primary motivation behind the recent change:
Prior to the addition of the blow-through floor, acceleration limits, as defined by the International Organization for Standardization, were predicted to be significantly exceeded, indicating performance that would be unacceptable.
According to a letter from Magnusson Klemencic Structural and Civil Engineers, this would result in building occupants feeling ill and possibly afraid for their safety.
WTF?! Hey honey, the gold fish bowl is sloshing around again.
In other words, the luxury tower would sway uncomfortably without the addition.
These sorts of wind breaks are not uncommon on very tall and very slender skyscrapers. New York’s 432 Park Avenue utilizes five such gaps across its 1,396-foot elevation. With the Manhattan supertall, however, these spaces were always part of the plan so they double as mechanical floors and feature attractive nighttime lighting.
This will not be the case with Vista’s blow-through floor. According to CAB, by law the space cannot be illuminated. The result is likely to appear as a dark horizontal band across the Studio Gang/bKL-designed building’s uppermost extremity.
Other mid-stream changes to the Vista plan include a revised, less complicated exterior glass system that ditches green coloring for more bluish tones. The architectural top of the building has grown by a handful of feet, now appearing to top-out at 1,198 feet. Diagrams also show the tip of Vista’s crown tapering less compared to previous illustrations.
Because O'Donnell needed to build tall (and thus profitably), 150's north and south flanks look as thin as a reed. Their aspect ratio — the building's height relative to the width of its core — is a jaw-dropping 20-1. Imagine a reed blowing in the wind. Now imagine that that reed is an office building with people inside who get as queasy as passengers on a storm-tossed ship.
To prevent that, the engineers inserted two enclosed concrete vaults near the building's top. The water in the vaults, which are called "tuned liquid dampers," is not for swimming. When the wind pushes the high-rise one way, the water sloshes the other way, damping wind-induced sway and eliminating the threat of rattling chandeliers and whitecaps in the toilets.
Park Tower is a skyscraper located at 800 North Michigan Avenue in Chicago, Illinois. Completed in 2000 and standing at 844 feet (257 meters) tall with 70 floors — 67 floors for practical use, it is the twelfth-tallest building in Chicago, the 43rd-tallest building in the United States, and the 83rd-tallest in the world by architectural detail. It is one of the world's tallest buildings to be clad with architectural precast concrete (the Transamerica Pyramid Building in San Francisco is taller).
It is one of the tallest non-steel framed structures in the world—it is a cast-in-place concrete framed structure. This building was originally intended to be 650 ft (200 m) tall. But later, the ceiling heights were increased allowing it to reach 844 ft (257 m).
The building occupies a footprint of 28,000 square feet (2,600 square meters). Because of the small footprint and the fact that it is a non-steel-framed concrete building, this is the first building in the US to be designed with a tuned mass damper from the outset.
While other skyscrapers in America have anti-sway systems, they were always added later. A tuned mass damper counteracts wind effects on the structure. (The 300-ton damper is a massive steel pendulum hung from four cables inside a square cage.) Because of its massive weight, the damper has inertia that helps stabilize the building from swaying in the wind.
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