CESP Building 2 (Sede II), a 21-storey cast-in-place reinforced-concrete office tower on Avenida Paulista in São Paulo, suffered a fire-induced collapse of its central structural core on the evening of 21 May 1987, roughly two hours after the fire reached the building, killing one company employee and injuring some 300 people. The proximate cause was not the loss of concrete strength alone but a mechanism that designers of the period rarely considered: the thermal expansion of fire-heated T-beams, which drove the spanning floor system outward against an asymmetrically stiffened frame and overloaded its vertical members in shear until the core failed and pancaked through the full height of the building.
This is one of the few documented cases in the engineering literature of a complete fire-induced collapse of a reinforced concrete office structure, and it failed in a way that contradicted the assumption that concrete buildings simply “burn out” rather than fall. The central region — the bay containing the elevator shafts — lost its vertical support and dropped as if imploded, splitting the tower into a front and a rear portion; the front section was so damaged it had to be demolished days later.
Sede II was a building of conventional 1960s design: parallel reinforced-concrete frames carrying T-beams of 8 to 11 metre span at roughly 8 metre spacing, with ribbed floor slabs, in a tower paired with the 19-storey Sede I. On paper it was an ordinary structural solution. Its fatal characteristics were the absence of vertical fire compartmentation, inadequate horizontal separation, and a stiffness asymmetry — stiff columns clustered at the elevator core on one side of each frame — that concentrated the expansion forces where the frame was least able to resist them.
The forensic literature did not treat the collapse as bad luck. Studies of São Paulo’s concrete-structure fires, published alongside analyses of the earlier Andraus (1972) and Joelma (1974) towers, concluded that this structural solution “from the point of view of fire safety must be avoided.” The CESP case became a demonstration that a reinforced-concrete frame is not automatically a fireproof frame: heated to large thermal dilation, with no compartmentation to limit the fire’s reach and an asymmetric load path to amplify the strain, even concrete can be made to collapse.
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The Joelma Building, a 25-storey reinforced-concrete office and parking tower on Avenida 9 de Julho in downtown São Paulo, was burned out internally on 1 February 1974, killing roughly 179 people — counts cited between 179 and 189 — and injuring about 300, of the 756 occupants present that morning. The proximate ignition was trivial: a twelfth-floor air-conditioning unit, wired to bypass the floor’s electrical control panel, overheated and short-circuited. What turned that ordinary electrical fire into Latin America’s deadliest high-rise fire was a structural and architectural omission — the building had no fire compartmentation of any kind, and its interior was lined with combustible material. The fire flashed through the entire tower in roughly twenty minutes.
This was not a structural collapse. The reinforced-concrete frame survived — precisely because the combustible contents burned so fast that the concrete was never held at failure temperature long enough to lose capacity — and the building was later repaired and returned to service. The failure under forensic examination is a different one: the total absence of the vertical and horizontal fire separation meant to keep a fire on the floor where it starts. Without fire walls, fire-rated floors, sealed shafts or a protected stair, the building behaved as a single continuous volume — a chimney, drawing fire and smoke upward through every storey at once.
Completed in 1971 and designed by Roberto Aflalo, the Joelma was a modern Brazilian skyscraper of its decade: an efficient reinforced-concrete frame with open floor plates and a single common stairwell running the full height. Its combustible fit-out — wood, cellulose-fibre ceiling tiles, flammable curtains and carpet — laid a heavy fire load across all 25 floors, with no sprinklers, alarm, smoke control, fire-rated stair enclosure or compartment boundaries to interrupt the spread.
The investigation and the engineering literature that followed did not treat the toll as bad luck. The fire came less than two years after the 1972 Andraus Building fire in the same city; together the two events — more than 200 dead — exposed that São Paulo’s tall buildings were being built and occupied with essentially no enforced fire-safety regime. São Paulo issued formal fire-safety regulations by municipal decree within days, and the case became the founding text of Brazilian high-rise fire law. Joelma is now a byword for a single lethal lesson: a building with no compartmentation is not a stack of floors but one open shaft, and an open shaft burns all at once.
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