Clash between modern engineering interpretations and traditional  non-engineered knowledge seems to have come to a head

Kathmandu

There have been heated discussions on how reconstruction must be done to ensure that the new structures are built so strong that they survive the next earthquake. We assume to have learnt to tame nature by creating materials and designs that withstand the enormous seismic forces. In a certain sense, it might be correct, but our present society does not seem to consider the need to plan over longer periods.

In Nepal the problem we face is that large earthquakes only occur every 80 to 100 years. This theory was proven by the April 25 Earthquake that occurred 81 years after the Great Nepal Bihar Earthquake of 1934. There is an entire generational gap between the earthquakes, which dims the memories that are passed on. We forget the lessons from the previous earthquake. So who cares what happens in 2095? Most of us won’t be here anyway. Though we say that we must reconstruct our monuments to withstand the next earthquake, our solutions tend towards ensuring that the structures do not collapse within the next 25 years.

The clash between modern engineering interpretations and traditional non-engineered knowledge seems to have come to a head. Reconstruction is being proposed using modern engineering parametres without even properly assessing the performance of the traditional structure or understanding the reason for the damage or collapse. Why did the central timbre mast of the Bouddhanath Stupa get damaged? Was it because of the base of the harmika had been caste using cement concrete? Was the brick masonry in mud mortar in the plinth of Pratappur temple shattered by the recent reconstruction of the superstructure in the more rigid lime-surkhi mortar? Did the upper part of the nine-storey palace at Hanuman Dhoka collapse because of the fracturing of a reinforced cement concrete tie-beam introduced

in the 1970s restoration? There were several tiered temples that collapsed that had concrete tie beams. What was the cause of the collapse? Even the collapse of Kastamandap raises questions concerning earlier interventions rather than design faults.

The lack of understanding of traditional structures is alarming. In the rush to reconstruct certain monuments, simplified procedures are used. It is important to understand that restoration project of Kastamandap in 1970s covered up the fact that one of the main four central posts was not resting on a saddle stone. At the base of many of the posts, tendons were missing and holes in saddle stone filled. The structure probably collapsed because it was not locked to the plinth and was standing on only three out of four main posts. Further research and documentation is required to fully understand what was happened.

The traditional structures have not been built to withstand an earthquake. They perform in a manner to dampen or even

utilise the forces. For example, use of wooden pegs allows for connections to tighten instead of being damaged. The characteristics of the materials that are brought together within a structure need to be compatible. This performance of traditional buildings brings us to the ancient fables of tree and reed. The mighty tree stands tall and withstands the storms but crashes down when the forces become too great. The reed will move to the slightest breeze but not even the most vicious storms can break the supple plant.

(The author is an architect and can be contacted through paharnepal@hotmail.com)