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High-rise Office Building Fire One Meridian Plaza Philadelphia, Pennsylvania


One Meridian Plaza is a 38-story high-rise office building, located at the comer of 15th Street and South Penn Square in the heart of downtown Philadelphia, in an area of high-rise and mid-rise structures. On the east side, the building is attached the 34-story Girard Trust Building and it is surrounded by several other high-rise buildings. The front of the building faces City Hall.

One Meridian Plaza has three underground levels, 36 above ground occupiable floors, two mechanical floors (12 and 38), and two rooftop helipads. The building is rectangular in shape, approximately 243 feet in length by 92 feet in width (approximately 22,400 gross square feet), with roughly 17,000 net usable square feet per floor. (See Appendix A for floor plan.) Site work for construction began in 1968, and the building was completed and approved for occupancy in 1973.

Construction was classified by the Philadelphia Department of Licenses and Inspections as equivalent to BOCA Type 1B construction which requires 3-hour fire rated building columns, 2-hour fire rated horizontal beams and floor/ceiling systems, and l-hour fire rated corridors and tenant separations. Shafts, including stairways, are required to be 2-hour fire rated construction, and roofs must have l-hour fire rated assemblies.

The building frame is structural steel with concrete floors poured over metal decks. All structural steel and floor assemblies were protected with spray-on fireproofing material. The exterior of the building was covered by granite curtain wall panels with glass windows attached to the perimeter floor girders and spandrels.

The building utilizes a central core design, although one side of the core is adjacent to the south exterior wall. The core area is approximately 38 feet wide by 124 feet long and contains two stairways, four banks of elevators, two HVAC supply duct shafts, bathroom utility chases, and telephone and electrical risers.


The building has three enclosed stairways of concrete masonry construction. Each stairway services all 38 floors. The locations of the two stairways within the building core shift horizontally three or four times between the ground and the 38th floor to accommodate elevator shafts and machine rooms for the four elevator banks. Both of these stairways are equipped with standpipe risers.

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Adjacent to the stairway enclosures are separate utility and HVAC shafts. There are pipe and duct penetrations through the shaft and stairway enclosure walls. The penetrations are unprotected around the sleeved pipes and fire dampers are not installed in WAC ducts penetrating the fire-resistance rated wall assemblies. This effectively creates many openings between the utility shafts, and the individual floors, primarily in the plenum area above the ceilings, as well as between the shafts and the stairway enclosures.

The third enclosed stairway is located at the east end of the building. This stairway attaches the floors of the Meridian Plaza to the corresponding floors of the Girard Trust Building. Adjacent to the east stairway is an additional enclosed utility shaft which also has pipe and duct penetrations through the shaft enclosure walls. There are no fire or smoke barriers around the sleeved pipes and no fire dampers in the HVAC ducts that penetrate the shaft walls. Elevators

Elevator service is provided by four zoned elevator banks identified as A through D. Elevator Bank A serves floors 2-11. Elevator Bank B has two shafts which enclose seven elevators: six are passenger elevators that serve floors 12-21, and one is a freight elevator that serves floors 22-38. Elevator Bank C serves floors 21-29, and Elevator Bank D serves floors 29-

37. The elevator shafts are constructed of concrete and masonry and extend from the first floor or lower levels to the highest floor served by the individual elevator banks. At the top of each elevator bank is the associated elevator equipment room.

The elevator shafts that serve the upper floors are express rise and do not have openings to the lower floors. Only the Bank C passenger elevators and the freight elevator served the fire floors. The elevator shafts did not appear to play a significant role in the spread of combustion products.

Each elevator lobby is equipped with a smoke detector that, when activated, recalls the elevator cars to the first floor lobby. Firefighter’s service (elevator recall) features were added in 1981 under provisions of

Heating, Ventilation, and Air Conditioning

The heating, ventilation, and air conditioning (HVAC) system is composed of four air handling systems. Two systems are located in the 38th floor mechanical room and service the east and west halves of the upper floors. The other two systems are located in the 12th floor mechanical room and service the east and west halves of the lower floors. Each system supplies air to its respective floors through one or two supply air shafts located within the building core and receives return air from its associated return air shafts.

Return air shafts are located at each of the four building comers. Upon examination at selected locations, the HVAC supply and return air shafts did not appear to have fire dampers at the duct penetrations on each floor.


The bathroom utility piping extends through the 38 floors through pipe chases that are formed by the space between two walls. These pipe chases transfer location as the bathroom locations change floor to floor. Upon a sample examination of the pipe chases, it was found that floor penetrations were not closed or sealed to maintain the integrity of the fire-resistance rated floor/ceiling assemblies.

Electrical and Communications Risers

The electrical and telephone risers are enclosed in separate rooms on each floor. The rooms are located directly above one another and are intended to function as vertical shafts, with rated separations required at horizontal penetrations from the shafts into floor and ceiling spaces at each level. Within the telephone and electrical rooms, unprotected penetrations of the floor assemblies allow conduits and exposed wires to travel from floor to floor. Several breaches of fire-resistance rated construction were observed in the walls separating the electrical and telephone rooms from theceiling plenums and occupied spaces on each floor.

Emergency Power

The building electrical system receives power from two separate electrical substations and is backed-up by an emergency generator. The two sources of power are arranged so that the load would automatically transfer to the second source upon failure of the first. Electrical power for One Meridian Plaza and four adjacent buildings is distributed from the basement of 1414 S. Penn Square.

The electric service enters the building via the basement from the adjoining building and is distributed to the 12th and 38th floor mechanical rooms via the electrical risers in the building core. From the 12th and 38th floor mechanical rooms, electrical power is distributed to the major mechanical systems and to a buss bar riser, which services distribution panels on the individual floors.

Emergency power was provided by a 340 kw natural gas-fired generator located in the 12th floor mechanical room. The generator was sized to supply power for emergency lighting and the fire alarm system, the fire pump located on the 12th floor and one car in each bank of elevators. The generator’s fuel was supplied by the building’s natural gas service. This generator was not required by the building code, since the building’s electrical power was supplied by two separate substations.

The generator was reported to have been tested weekly. The last recorded test date was January 30, almost four weeks before the fire, and the maintenance records indicate that problems were encountered during engine start-up under load conditions at that time. During a detailed inspection following that test, a damaged part was discovered and replaced. After the repair, the generator was started without a load and appeared to work properly, but no subsequent tests were performed to determine if the problems persisted under load conditions.

Records of earlier maintenance and test activity suggest that load tests were performed only occasionally. Test and maintenance records indicate a long history of maintenance problems with the emergency generator system. Many of these problems became manifest during or immediately after conducting tests under load.

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