Civil Engineering Reference
In-Depth Information
(1971)
Four workers died when approximately two-thirds of a 16-story apartment building
under construction in Boston collapsed on January 25, 1971. Almost 7,260 tonnes
(8,000 tons) of debris were removed before the bodies of the workers could be
recovered. The building had been in development for more than six years.
Fortunately, the collapse occurred slowly enough that most of the people working on
the site were able to escape. The building was cast-in-place reinforced concrete flat-
slab construction with a central elevator shaft core. This style of construction is
popular for multistory buildings because it reduces the slab thickness and the overall
height of the building. The flat slabs were 190 mm (7 1/2 in.) thick, except for some
bays near the elevator core and at stairwells, which were 230 mm (9 in.) thick. This
design made possible a story height of 2.7 m (9 ft) for most of the floors. Figure 5-5
shows the floor plan.
The building, located at 2000 Commonwealth Avenue, was designed to be 16
stories high with a mechanical room above a 1.5 m (5 ft) crawl space on the roof. The
building was 55.1 m
20.9 m (180 ft 10 in.
68 ft 6 in.) in plan. The structure also
had two levels of underground parking. A swimming pool, ancillary spaces, and one
apartment were located on the 1st floor, and 132 apartments were on the 2nd through
16th floors. Originally, these apartments were to be rented, but the owners later
decided to market them as condominiums.
At the time of collapse, construction was nearing completion. Brickwork was
completed up to the 16th floor, and the building was mostly enclosed from the 2nd to
the 15th floors. Plumbing, heating, and ventilating systems were being installed
throughout various parts of the building. Work on interior apartment walls had also
started on the lower floors. A temporary construction elevator was located at the
south edge of the building to aid in transporting equipment to the different floors. It
is estimated that 100 people were working in or around the building at the time of the
failure.
The failure took place in three phases. These phases were punching shear
failure in the main roof at column E5, collapse of the roof slab, and, finally, the
progressive and general collapse of most of the structure. Figure 5-6 shows the extent
of the collapse.
Lessons Learned
A commission of inquiry was appointed by the mayor of Boston and convened a
week after the collapse. The commission made a number of important findings
(Granger et al., 1971):
Not a single drawing found in the file carried an architect's or engineer's
registration stamp. The structural engineer refused to provide the
calculations supporting his design to the commission. No principal or
employee of the general contractor held a Boston builder's license.
