Consulting-Specifying Engineer - March 2009 - (Page 35) Fire and life safety in a high-rise This tale of two high-rise fires teaches one thing: Specifications, standards, and building and fire codes can make a difference between life and death. BY JIM ARNOLD, Clark County (Nevada) Dept. of Development Services typical building fire begins slowly, as combustible materials are gradually warmed by a heat source to their ignition temperature. The level of fire protection installed within a building and the response of the local fire department will determine whether a fire is controlled or grows into an inferno. This article will describe the extremely different outcomes of two similar fires in two similar high-rise buildings and will explain why one event became a catastrophe while the other garnered merely a brief mention on the nightly news. Recipe for disaster The first fire is the disastrous Feb. 1, 1974, high-rise fire at the 25-story Joelma Building in Sao Paulo, Brazil. This reinforced concrete skyscraper was built from 1969 to 1972. Banco Crefisul occupied most of the building, and the bank offices held a considerable fire load of desks, papers, curtains, carpets, plastic insulation and wall coverings, and wooden walls. The bottom eight stories were occupied by a parking garage. Emergency egress was limited to a single stairwell that was not built as a fireproof enclosure. The building had no fire walls, emergency lighting, fire alarms, fire sprinkler system, fireproof emergency exits, posted evacuation plans, emergency signage, or smoke control system. A The fire began at 8:50 a.m. An air conditioner on the 12th floor overheated and started the fire. The air conditioner circuit required a special circuit breaker that had been omitted because it was not available at the time of installation. The circuit was installed to bypass the electrical control panel on the 12th floor. The lack of this simple protective device allowed the air conditioner motor to overheat and set fire to adjacent materials. Due to combustible products used throughout the building, the fire spread quickly, and the building was engulfed in flames within 20 minutes. The fire was discovered soon after it started but was initially reported to the Sao Paulo Fire Dept. by a resident of an adjacent building nearly 15 minutes later. The first responding units arrived 5 minutes later and immediately called for backup. The fire crews entering the single stairway were unable to proceed up the stairway beyond the 11th floor, which was the first business office level. The single open stairway burned to the 15th floor and filled the remaining building height with smoke and heat, preventing use as the intended fire escape. Evacuation Nearly 300 people were evacuated using the four elevators. The elevator operators were only able to make a few trips before the elevator shafts filled with heat and smoke, making further rescue by elevator impossible. Lacking a feasible escape path, approximately 170 people sought refuge on the roof. Some reports claim as many as 100 people may have been rescued by helicopters from the top of the burning building. One extremely brave police officer hastily rigged horizontal ropes to an adjacent building and led 18 occupants to safety on this thin lifeline. Approximately 80 people found shelter under the building roof tiles and were later found to be the lone survivors on the rooftop. Some fortunate office workers survived by climbing onto ledges or balconies that had sufficient protection from the flames and smoke, primarily in the corners of the building. A few brave occupants lowered themselves from floor to floor using the balconies, past the ascending flames to a level where they could be reached by aerial ladders or were hidden from the rising fire. Few aerial ladder rescues were made during the fire because the lower building levels accessible to the ladder trucks consisted mainly of a parking structure occupied by vehicles, not people. The fire truck aerial ladders were able to extend only to the lowest occupied floors. The fire’s intense flames heated the concrete walls to very high temperatures. This high heat expanded the air and water vapor inside microscopic bubbles in the concrete, resulting in an explosive spalling of the concrete, sufficient to expose reinforcing steel Consulting-Specifying Engineer • MARCH 2009 35
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