Tuesday, August 1, 2017
Source: Elevator World
High-rise buildings, 1,000-plus-ft. in height, proliferating in southern California? That was unimaginable not that many years ago, but today, such structures – the largest of them known as “supertalls” – are dotting the West Coast landscape in increasing numbers and forming a typically more East Coast/Midwest-style urban skyline. For most of the 20th century, high-rise development in California was limited by seismic, financial and other practical issues. Most residents of Los Angeles, for instance, lived in houses or apartment buildings of three or fewer stories. In light of concern about earthquakes, it was much easier, if not prudent, to grow the city with “short” buildings that were safer and allowed developers to spread their risk across many smaller structures, instead of fewer large ones. Such smaller buildings did not involve the huge capital investments required by tall construction and the associated costs in money and time for engineers, drawings, approvals and construction, while the area’s population was insufficient in number and wealth to timely fill major structures and make them profitable.
However, California today is virtually a completely different place. The region is undergoing continuous, explosive growth, with an accompanying need for the commercial and residential infrastructure to support it. Many of the factors that have driven high-rise construction in New York City, Chicago and other more eastern business centers are now within minutes of the Pacific Ocean. The region is becoming increasingly more upscale. Land costs are extremely high and climbing, making it advantageous to “go big” and construct the tallest possible buildings on the smallest possible footprints.
Today’s advanced building-construction techniques and emerging technologies are allowing this to happen. Among these is the car-top emergency exit seismic switch, a safety device developed for use in the elevator industry to help protect passengers and equipment. During an earthquake, it would not be unusual for an elevator to experience a loss of power and entrap passengers. A car-top emergency-exit seismic switch, installed in the hatch door lock, protects passengers and their rescuers from injury resulting from unexpected movement caused by suddenly restored power. Louis “L.J.” Blaiotta, Jr., Columbia Elevator Products Co. Inc.’s CEO, explains:
“For our cabs built to be installed in seismic zones, we have devised a special ‘seismic lock’ for the emergency exit. Rather than resetting automatically when the emergency hatch door is closed, these locks must be reset manually. This is designed to avoid a situation where, after a rescue worker has opened the hatch to allow passengers to escape, a tremor occurs and accidently causes a conventional lock to automatically turn back on and close the safety circuit. With our seismic lock, a human must take the considered, conscious, secondary action to physically/manually reset the switch to turn the elevator back on. This is an extra step implemented only in seismic zones, both for high-rise and shorter buildings, while, in non-seismic zones, conventional locks that can automatically reset the safety circuit when the emergency hatch is closed can be used.”
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