Consulting-Specifying Engineer - January 2008 - (Page 39) gets into the whole discussion of refuge floors,” he said. “We are working on a very tall building in Seoul, Korea, which is 1,800 ft tall. It is a multi-use building where there is retail, office space, restaurants, hotel, and observation deck and bar at the top of the building,” Galioto said. “So there’s a whole stack of different uses. Given the height—close to 120 stories—we decided to compartmentalize the building vertically because it is unrealistic to expect people to walk down 120 floors.” The designers came up with the concept of transitional refuge areas. Transitional refuge areas are fire-rated, pressurized spaces at various locations in super-tall high-rises where occupants can briefly rest in a protected environment before continuing their evacuation by stair or protected elevator. But will all these robust designs become the conventional approach? Most buildings won’t be designed to the specifications of WTC Tower 1, but the designs may well have an effect on building elsewhere. “We do have other clients who are asking for these things,” Galioto said. “We are looking into a variation for other high-rise buildings—not to have the additional stair but to look toward the proposals that exist in Europe, and have the protected elevator open onto a vestibule that adjoins one of the primary exit stairs of the building. So I think that’s the more standard case if we’re considering a 50- or 60-story building.” Stairways to safety Another way in which 7 WTC went beyond the code minimums was stair width—with 72-in. wide stairs. “There’s quite a bit of research which would support the notion that stairs, as they currently exist, are too narrow,” Galioto said. “We’ve found that the standard 44-in. wide stairs are just too narrow to allow two people to walk side by side. Most expert studies support the fact that instead of 44 in., the stairs should be in the range of 60 to 66 in. wide. That will allow two people to walk side by side comfortably, holding onto a handrail. That’s a measure that we’ve taken in several buildings—the designs for several buildings not yet competed.” The 2006 editions of NFPA 101, Life Safety Code, and NFPA 5000, Building Construction and Safety Code, already include text requiring 56-in. minimum stair widths for those stairs serving 2,000 or more occupants. This provision typically applies to buildings of 14 or more stories and serves to facilitate occupant egress and counterflow of emergency responders traveling up the stairs. Another issue being addressed by recent code revisions is the required number of stairways in a high-rise building. “The 2007 Supplement to the International Building Code requires three stairways if the building is more than 420 ft. tall. And that’s the only parameter,” said Raymond Grill, PE, principal at Arup and the leader of Arup Fire in the Americas. “There are many cases where three stairways are excessive and many are pushing to rescind the requirement.” In addition, awareness of exits has become a major concern, especially horizontal transfer passageways from one staircase to another. It is proposed for the new codes that new provisions require that horizontal components of egress paths be marked by approved exit or directional signs. Evolving codes This brings us full circle back to the NIST study. The study is a point of departure in discussing ingress and egress system for tall buildings because of its profound effect on recent proposals and changes to the national building codes. Jeffrey Tubbs puts it succinctly: “From a broader perspective, people are waiting to see where the codes are going to head. There have been a number of initiatives that have gone forward. For instance, the NFPA high-rise committee has been looking at recommendations and contemplating changes to codes, and the International Codes Council Code Technology Committee has a number of initiatives as well.” The focus here has been on egress systems, but there is much more ground left to cover on all types of fire protection systems for tall buildings. Anyone can claim to save you a lot. AERCO. The only manufacturer with UL-confirmed efficiency. Benchmark Boilers. Condensing is just part of the savings. Even before UL confirmed the efficiency of our BMK2.0LN, we knew our unmatched 20:1 and 15:1 turndown would virtually eliminate cycling losses, minimize wear and tear, and improve temperature control. And with no need for primary pumps, three-way valves or extra heat exchangers, Benchmark boilers streamline system designs and reduce maintenance requirements. Plus, our flexible venting and air intake options also help lower project costs. To learn more visit www.aerco.com/bm2 Heat You Can Bank On Copyright 2008 AERCO International, Inc. Consulting-Specifying Engineer • JANUARY 2008 39 Input #222 at csemag.com/quickResponse http://www.aerco.com/bm2 http://www.aerco.com/bm2 http://csemag.com/quickResponse
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