Structures designed to protect buildings from earthquakes
Earthquake-resistant or aseismic structures are designed to protect buildings to some or greater extent from
seismic activity than their conventional counterparts. According to building codes, earthquake-resistant structures are intended to withstand the largest earthquake of a certain probability that is likely to occur at their location. This means the loss of life should be minimized by preventing collapse of the buildings for rare earthquakes while the loss of the functionality should be limited for more frequent ones.[1]
To combat earthquake destruction, the only method available to ancient architects was to build their landmark structures to last, often by making them excessively stiff and strong.
Currently, there are several design philosophies in earthquake engineering, making use of experimental results, computer simulations and observations from past earthquakes to offer the required performance for the seismic threat at the site of interest. These range from appropriately sizing the structure to be
vibration control technologies to minimize any forces and deformations. While the former is the method typically applied in most earthquake-resistant structures, important facilities, landmarks and cultural heritage buildings use the more advanced (and expensive) techniques of isolation or control to survive strong shaking with minimal damage. Examples of such applications are the Cathedral of Our Lady of the Angels and the Acropolis Museum.[citation needed
]
Trends and projects
Some of the new trends and/or projects in the field of earthquake engineering structures are presented.
Building materials
Based on studies in New Zealand, relating to 2011 Christchurch earthquakes, precast concrete designed and installed in accordance with modern codes performed well.[2] According to the Earthquake Engineering Research Institute, precast panel buildings had good durability during the earthquake in Armenia, compared to precast frame-panels.[3]
Earthquake shelter
One Japanese construction company has developed a six-foot cubical shelter, presented as an alternative to earthquake-proofing an entire building.[4]
Concurrent shake-table testing
Concurrent shake-table testing of two or more building models is a vivid, persuasive and effective way to validate earthquake engineering solutions experimentally.
Thus, two wooden houses built before adoption of the 1981 Japanese Building Code were moved to E-Defense[5] for testing. One house was reinforced to enhance its seismic resistance, while the other one was not. These two models were set on E-Defense platform and tested simultaneously.[6]