Assessing the damage
- There is a need to investigate why some buildings fell during the earthquake and others stood
May 12, 2015-
A growing consensus seems to be that a lesson learned from the April 25 earthquake is that the cement post and beam system is the correct one for earthquake prone regions.
Noting that not all old buildings fell, whereas a good number of the new cement ones did, an anthropologist friend cautioned that a thorough investigation of why buildings of all sorts fell and others stood needs to be undertaken before conclusions can be drawn. She advised surveying as many collapsed and surviving buildings as possible to trying to get a sense of what causes buildings to collapse or stand.
Nepal’s architectural schools could immediately commence such a project of assessing as many buildings as possible before cleanup and reconstruction progresses based on uninformed prejudices. Such a real-life laboratory could make Nepal’s architects into world experts in the architecture of earthquake-prone regions.
In slightly larger earthquakes elsewhere, post and beam buildings failed catastrophically, causing many more deaths. Countries such as Haiti haven’t still been unable to clear out non-reusable cement rubble.
On an investigation of buildings that failed, I sensed it may not have been the type of construction but design flaws and poor maintenance that led many to collapse.
The joists, or beams that hold the floors up in many older buildings tend to run only from side to side tying together the two sides of the buildings but not the fronts, which peeled away while the sides even in very old buildings often remained standing.
Poor brickwork in many old buildings furthermore allowed cracks to expand easily. A good mason alternates bricks at the corners of buildings and sometimes inserts long stones periodically in the corners so the sides and the fronts of the buildings are woven together. Many of the buildings that collapsed or cracked had instead inserted broken pieces of brick at the corners or simply set one wall—oftentimes a new front wall—against the others without any interweaving at all. Not surprisingly, gaps were allowed to extend unimpeded between the front and side walls often leading to collapse.
Ornate mantles dividing the stories in many old buildings in Nepal also served as breaks in the brickwork that stopped cracking while adding beauty to the buildings. Old builders framed their windows with long heavy sills and headers that extended far into the walls below and above the windows, stopping cracks before they could extend up and break the building apart. Windows were set irregularly at different heights and distances to accentuate the effect. Buildings that omitted these features allowed cracks to run unimpeded.
A rotten or poorly constructed roof can become an Achilles heel in a building. Leaks rot structural elements. Failure of the roof structure to hold together the walls causes them to collapse, bringing down the subsequent floors below them. In many of the old buildings people dealt with rotten roof framing by covering it with corrugated metal without repairing the structure leading to roof collapse.
Cement post and beam construction has its own problems which, from experience elsewhere in the world, may become universally apparent in a slightly larger earthquake.
Cement post buildings tend to be rectangular with regularly placed features, making them not just architecturally monotonous but dangerous. They are weakest at joints in the corners, and heavy loading of thick cement floors and ceilings makes them more vulnerable and lethal in slightly larger quakes.
Hill communities have recently been abandoning clay construction for stone, which architects building dirt-bag schools near the epicenter of this quake noticed were prone to collapse, particularly when they used smaller stones.
Buildings don’t have to be rectangular. A great Indian architect featured several decades ago in South Magazine designed curved walls in his buildings. He said they are architecturally more interesting, save useless space lost in square corners, and are stronger. The architectural survey should look at what happened to the remaining round houses of the hill peoples of Nepal.
The same architect also eschewed the use of cement for bricks which he manufactured in simple molds. Saying that an architect should intimately know his materials by working them with his own hands, he disliked cement because it requires immense amounts of energy, it transfers heat much more easily thereby compromising savings in construction with greater lifetime costs, and it is not aesthetically pleasing. A friend from Dang, furthermore, told me that the heavy use of water by the cement factories in Dang and neighbouring districts has been drawing down the water tables and turning the area into desert.
Although cement is associated with modernism, it is not a modern material. It was invented by the ancient Romans 2,000 years ago in the service of the spread of empire by allowing the construction of massive structures of uniform design throughout the empire with no sense of place or respect for local materials, cultures, landscapes or ecology. When torn down it can neither be easily reused nor returned to the earth. Perhaps the status derived from the association with empire is confused with the idea of modernism which drives the infatuation for cement among the aspiring middle and upper classes of Nepal.
Local techniques, materials and knowledge have much to offer for not only making construction more earthquake resistant, but also in helping people recover a sense of and respect for their place and culture.
Individuals and groups are already working at recovering and combining old materials and techniques with contemporary knowledge, experience and styles. Beautiful rammed earth, bamboo, earth bag, and clay buildings are being constructed in Nepal. As demonstrated more than a half century ago by the visionary Egyptian architect Husan Fathy in his book Architecture for the Poor, such houses can be built much cheaply than cement, housing even poor people with dignity, beauty, safety and comfort.
Earthbag schools built near the epicenters of the quakes were unaffected by the quake, whereas more than a hundred of the new cement schools collapsed.
Cob, which antedated cement by thousands of years by mixing clay, sand and straw, is seeing a resurgence. Called ‘hand-sculptured’ due to its aesthetic beauty and comfort, low embodied energy, and reliance on knowledge as opposed to technology, was revived in 1960s England and subsequently inspired the emergence of many regional styles across the world. Cob is strongest where post and beam structures are weakest, in the corners. Constructed as one unitary structure woven together throughout by straw, cob has withstood earth quakes that leveled the modern cement structures in places like New Zealand.
This is all to say that conclusions being popularly drawn from the recent earthquake may be the wrong ones. Much may be learned from what was destroyed in this quake. Knowledge being lost in rubble and with the dying away of elderly artisans may offer solutions and protect us in the future. And trying to understand what happened, why it happened, and take lessons from the ruins must be undertaken immediately as an urgent project by the people who stand to shape future construction and the culture that is to arise from it.
Published: 13-05-2015 17:13