The Philippines is an earthquake prone country. Earthquake faults can be found spread out in the entire archipelago. For the same reason, builders in the country should anticipate this natural calamity. In fact, for responsible builders, seismic activity should govern the design of their structures.
Building a structure with earthquake in mind should not be extremely expensive. The primary objective is not to earthquake proof the structure, but to make it behave in such a way that its occupants can safely eject the building during a major earthquake and keep the damage to the structure at the minimum.
How is it done? How can we build earthquake resistant structures?
Build columns that are stronger than beams. While most people may argue that all structural components should be equally strong, that is not the case if we want to build structures that are earthquake resistant. An equally strong beam would create a scenario wherein both the columns and the beams fail in unison during a major earthquake. Even worse is when a beam is stronger than the column. In such case, the structure could colapse without warning. On the other hand, a weaker beam would fail first while the structure is still standing. This would warn occupants, giving them time to vacate the structure to safety before it totally collapses.
Build strong foundations. This is a no brainer. Earthquakes displaces the building through movement of the ground. A weak foundation would create large displacements, creating a higher risk of failure.
Decrease mass as height increases. Buildings with stories that are heavier than the stories below are at higher risk of failure as it creates bigger load-displacement (P-Delta) values.
While earthquakes may be unpredictable, it is possible to create structures that are safe while reasonably economical. Keep safe.
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