Posts tagged with "Seattle":
Seattle is updating building codes for new skyscrapers after a shocking study revealed that the power and nature of earthquakes in the region pose a significant threat to its tall buildings, one that is worse than experts could have imagined.
The Seattle Times recently reported on results from the M9 Project, a four-year study that aimed to estimate the effects of a magnitude 9 Cascadia earthquake, revealed that the vast, sediment-filled basin under Seattle can magnify the type of ground shaking that puts high-rises at risk of collapse by a factor of two to five, which can trigger stronger surface effects than earthquakes in nearby California.
When rattled by an earthquake, the Times explained, the region's glacial-packed soils, which can extend more than four miles underground, violently shake and convulse, trapping massive seismic waves within the basin that underlies most of the city. Intense shaking like this could last for two minutes, which is four times longer than the average quake. While shorter buildings under 10 stories can withstand the earth's back-and-forth motion, tall buildings tend to whip back and forth under those conditions until they are on the verge of collapse.
As the Times reported, as a result of these findings, Seattle and its neighbor, Bellevue, plan on revising seismic construction standards for new buildings over 240 feet, or over 20 stories tall. These standards will require high-rises to be stronger and more sturdy than their predecessors, without the additional cost.
The plan to revise building codes has also raised concerns regarding Seattle’s older high-rises, many of which were constructed between the 1960s and 1990s, prior to when the dangers of earthquakes were fully understood. Older high-rises have a greater risk of major damage and collapse due to their fracture-prone welded joints, which are supposed to secure the steel frame, as well as their poorly-reinforced concrete supports. Seattle’s renowned Rainer Tower, for example, with its golf-tee-shaped base, was built in the 1970s and undoubtedly has fracture-prone welds. According to the study, buildings like that are up to five times more likely to collapse during an intense earthquake than a modern building.In Seattle, where the seismic threat to skyscrapers is higher than in California because of the city's sedimentary basin, there have still been no attempts to research and pinpoint dangerous high-rises. While the city is taking steps forward by enhancing construction standards, retrofitting old concrete and steel high-rises may be the next necessary step. This may prove costly, but taking time to fix the underlying structure of older buildings could prevent serious levels of damage that can be catastrophic to the community.
NBBJ designed a trio of connected glass orbs with living walls at the new Seattle headquarters for online retail giant Amazon. According to an announcement on Amazon’s blog, the spherical design—a project seven years in the making—was “chosen due to its natural occurrence in nature and as a nod to historic conservatories, like Kew Gardens.” This atypical meeting place away from the typical office towers provides a treehouse-like environment for employees, complete with terraces, water features, soaring staircases, and wooden decking.
The construction required more than 620 tons of steel supported by a burly concrete base to buttress the triangular insulated glass units fashioned from modularized Vitro glass. The open floor plan comprised three spherical units enveloped in Ultra-clear Vitro Starphire low-iron glass, which allows for higher visible light transmission, heightening views from multiple angles. “Iron is what makes glass appear green," said Andre Kenstowicz, Vitro Glass manager on the project. "Low iron Starphire glass eliminates the 'green' hue of traditional clear glass so the only green that you see is from the 300 species of tropical plants inside of the Amazon Spheres.” There are around 40,000 plants in the project.
Like all three domes, the largest is glazed by the contractor Enclos with Vitro’s Solarban Solar Control 60 Low-E coating in double laminate, measuring approximately 90 feet tall and 130 feet wide. All 2,643 panels of glass achieve 73 percent visible light transmittance and a solar heat gain coefficient of 0.40 across the visibly sinuous surface. This film beneath the surface limits the amount of radiation entering and consequently helps the interior to remain a stable, cool temperature.
NBBJ designed this biophilic environment to “inspire creativity and even improve brain function," according to the company’s blog. Luckily the public also has year-round access to the stimulating habitat at the base of the garden in the visitor center. There, in the thick of it, Seattleites can experience biodiversity in the heart of the city.
Structural Engineer: Magnusson Klemencic Associates
Glass Manufacturer: Vitro Architectural Glass, Northwestern Industries, Kuraray
Glass Fabricator: Northwestern Industries, Inc.
Glazing Contractor: Enclos