why buildings fall down how structures fail pdf
It seemed almost unavoidable that having written a book entitled
Why Buildings Stand Up, I should be pushed by my friends (and my
wonderfully friendly editor, Edwin Barber) to write another calledwhat else?
-Why Buildings Fall Down.
I have at long last given in to the temptation of explaining
structural failures in lay language, a simple but exciting task, but
only because the coauthor of another of my books, Matthys Levy,
a master of structural design, has enthusiastically accepted to write
it with me.
He and I can apply eighty-five years of design and teaching
experience, and sixty of investigations into structural failures, to
the job of helping us relieve the fears of the uninitiated, while taking the reader on an interesting and, we hope, entertaining trip
that will make the reader see buildings as never before: with a
clear understanding of why they stand up and why, yes, but once
in a blue moon, they fall down.
Besides those we might have unjustly forgotten, we thank the following friends who helped us bring this book into print and do this
in an alphabetical order that is not to be interpreted as a hierarchy
Edwin F. Barber, our patient, friendly, encouraging, and skillful
Mindy Hepner, our word-processing expert who almost allowed us
to meet our schedule
Julie Hubley Levy, understanding critic, enthusiastic and loving
Landon Prieur, the Weidlinger Associates librarian, who ferreted
out valuable hidden sources of information
Carol B. Salvadori, private editor and copy reader to one of us,
who translated into correct English all the Italianate chapters
of this book
Erica Vogt and Midge Esterman, our extraordinary secretaries at
Weidlinger Associates, who, unbelievably, succeeded in putting
this book together.
Once upon a time there were Seven Wonders of the World. Now
only one survives: the mountainlike Pyramid of Khufu in the Egyptian desert near Cairo.
The other six have fallen down.
It is the destiny of the man-made environment to vanish, but
we, short-lived men and women, look at our buildings so convinced they will stand forever that when some do collapse, we are
surprised and concerned.
Our surprise may be partly due to the fact that most of us judge
buildings by their facades: They look beautiful when very old and
ugly when very young, the opposite of human faces.
But this kind
of judgment is superficial and misleading; a much better metaphor
for a building is the human body.
A building is conceived when designed, born when built, alive
while standing, dead from old age or an unexpected accident.
It breathes through the mouth of its windows and the lungs of its airconditioning system.
It circulates fluids through the veins and
arteries of its pipes and sends messages to all parts of its body
through the nervous system of its electric wires. A building reacts
to changes in its outer or inner conditions through its brain of feedback systems, is protected by the skin of its facade, supported by
the skeleton of its columns, beams, and slabs, and rests on the feet
of its foundations. Like most human bodies, most buildings have
full lives, and then they die.
The accidental death of a building is always due to the failure
of its skeleton, the structure. Since the readers of this book are
interested in learning why buildings fall down, they expect from
us an explanation of structural failures.
But just as medical doctors consider health to be the norm and disease the exception, and
gain most of their knowledge from illness, so engineers consider
standing buildings the norm and structural failures the exception,
although they learn a lot from failures.
Our readers then should
know why almost all buildings stand up.
This may appear a difficult task.
Buildings serve so many purposes and come in so many
They consist of so many materials meant to resist so many
kinds of loads and forces.
How can a mere layperson understand
how structures work?
1 Structural Failure
ording to the Old Testament, the early inhabitants of the
earth, the ancient Babylonians, were “of one language,
and of one speech.
” Linguists, with the help of archaeologists, paleontologists, and geneticists, have been able to
reconstruct between 150 and 200 words of this Babylonian-claimed
proto-world language, the earliest we know of in humanity’s one
hundred thousand years. It is a magnificent thought: one people,
But our earliest forefathers were not content. So
ambitious were they that they determined to build a city with a
tower reaching heaven, and God, offended by their pride, broke
their single speech into so many different languages that the Babylonians, unable to understand one another, were stymied in their
plan, and their tower collapsed. The God offenders were scattered
over the face of the earth: “Therefore is the name of it called Babel
[from the Hebrew balal (to mix up)]; because the Lord did there
confound the language of all the earth.”
Thus was the first structural collapse attributed to the Almighty,
an excuse denied to today’s engineers, despite events known in the
trade as “acts of God.” In their hearts, engineers know that a simpler explanation can be found for the collapse of the Tower of Babel.
Even the toughest stone would eventually crack under the weight
of more and more stones piled up on it, and even if the mythical
tower had not reached such a height, an earthquake would have
brought it down because the earthquake forces grow in proportion
to the weight of a building and the square of the height.
The shape of these man-made mountains is the most logical for
monuments of great height (up to 481 ft. [144m]) to be erected in
a country where the only available structural material was stone:
the local stone along the northern banks of the Nile used to build
the central mound and the white limestone of the southern Tura
quarries for the finished outer casings.
The Egyptians did not know
the block and tackle, did not use the wheel for transportation of
heavy loads, and knew no metal harder than copper.
It is amazing,
therefore, to realize that they cut, transported, and erected pyramid blocks weighing from 2.5 tons (2.3 million of them for the Great
Pyramid at Gizeh) to 20 tons (for the roof of the king’s chamber
2 Miracle on
ing Kong, the hyperthyroid gorilla from the classic 1933
Hollywood movie, climbs up the limestone face of New
York’s Empire State Building to escape his captors. From
his lofty perch, holding on to the spire with one hand, he
swats attacking planes with the other.
For the world’s largest gorilla,
no other image but the world’s tallest building could set the stage
for such a mortal combat.
Far above the landscape of other New
York skyscrapers, the Empire State Building (Fig. 2.1) rises
majestically, 1,250 ft. (381 m) into the sky, its top often shrouded
in low-hanging clouds.
On July 28, 1945, nearly three months after the defeat of the
Nazi government and the end of the war in Europe, on the very
3 Will the Pantheon
Stand Up Forever?
he pyramids of Egypt, all but one, have laughed at gravity,
heat, wind, rain, lightning, and earthquake for almost five
thousand years. They even survived with equanimity the guns
of the Ottomans, which turned on them, seeking to blast their
way into the treasures of the pharaohs.
But we, children of a different era, do not want our lives to be
enclosed, to be shielded from the mystery.
We are eager to participate in it, to gather with our brothers and sisters in a community
of thought that will lift us above the mundane. We need to be
together in sorrow and in joy. Thus we rarely build monolithic
monuments. Instead, we build domes.
The dome, equally curved in all directions, is a Platonic shape
of ideal perfection, a man-made sky apparently unbound and yet