Earthquake Proof Buildings
An Earthquake is a sudden movement of the ground, most times causing severe damages to building, fields or open ground and even beneath ocean or sea floors. These usually occur along volcanic areas. Earthquakes are measured on Richter scale. Seismology is the study of earthquake and seismograph is an instrument that is used to measure and record the strength and movement of earthquakes.
With the devastation caused by this natural occurring disturbance, there has been increased clamour and agitation for construction of buildings and structures that are quakeproof. Although protection to buildings can never be perfect, but it will be assuring to know that most buildings are quake-resistant in order to reduce the amount of human and capital lose usually associated with earthquakes.
Scientists and engineers are constantly working on several technologies and methods in order to come up with the best protection of buildings and structures against earthquake. There are available building techniques but none is 100% safe against land tremor and they include;
Earthquake Building Materials
- This is the first defence mechanism to be employed in the protection of buildings against earthquakes. Steel alloys have been used to construct buildings that have resisted quakes, on the other hand, glasses, bricks and concrete blocks are poor materials for building earthquake proof buildings. Using quake resistant materials for buildings is not enough; therefore proper building structure and planning should be carried out prior to the erection of building. Experts on building are the best source for advice and suggestions that will help in construction. For example, one degree error when constructing the foundation of a skyscraper can lead to close to ninety degree error at the top of the skyscraper.
Earthquake Outrigger System
- This system supports buildings during earthquake but has disadvantage in that it can fail due to force from collapsing structure thereby feeding wrong information to the system.
Earthquake Isolated Base Technology
- This technique uses a coil or any other flexible support placed in between the structure's foundation. There is a movement interaction with the seismic waves, thus if the earthquake moves the foundation in one direction, the support will move the opposite direction and this confers immobility to the building. Some modern building are incorporated with cross-supports in between frame support, these also hold building together during tremor.
All these methods are expensive to build; therefore cheaper techniques are being sorted for. This is to ensure that majority of home owners can benefit. But it is important to consider the amount lost during earthquake then compare it with the cost of building quake resistant building. The best form of protecting large number of buildings from earthquake is the use of light materials from the foundation up to the roof. This ensures that beams are fixed together with bolts with little space in between them. The house is held firmly to the ground; therefore the use of steel beam for the foundation is the best option. This beam is driven deep down into the ground down to the underlying bedrock sediments. This method is only for those about to build, what about those already erected buildings? It has been suggested that steel sheet should be used to encircle such building and attached to steel beam down into the ground.
In cities prone to earthquake, the construction of less high building is the beginning of resistance to tremor. For example prior to the update in technology on building quake resistant building, in Japan buildings those are twelve storeys tall were not encouraged. Now, most high rising buildings in Japan adopt one technique; they drive foundation beams deeper down into solid ground.
There are three major effects prior and after earthquakes that tend to cause building collapse, therefore just building quake resistant structure is not entirely the best solution from collapse. Consider the following;
- During tremor, there is sudden horizontal and vertical accelerated movement of the ground, this rattles the building and cause jerking of the building
- Then vibration of the building follows, this is due to shock waves. The building is moves forth and back which produce great sways of materials and items in the building
- The last is the after shock, where the internal walls brace itself for swaying. This will cause movement and subsequent collapse
Earthquake Building Considerations
There are simple things needed to be put into consideration prior to building a home and they include;
- Are you in a volcanic active region, are you about to erect on a seismic line?
- Do you have the right materials to build a quake resistant house?
- Are you willing to use the simplest materials (wood, timber etc) to build a house
Earthquake Building Tips
- Ground steel beam should be designed and joined together by at least one foot apart; this should allow an overlap on the line of the building.
- Build floors with light materials like timber, plywood and clipboard with bolts firmly attached to the steel beam.
- Construct walls with light materials also
- The use of glass, bricks and hollow blocks should be minimised while building
- Tie walls, floors, roofs and foundations to a rigid box of steel. This is based on the fact that earthquake exerts sideways load on buildings
- In apartment buildings, concrete panels should be setup both horizontally and vertically to surrounding rooms in the building. These panels hold the structure and conserve its firmness.
- Modular building system should be encouraged. This allows beams and ready-made stacks to be connected together. This type of walls can resist tremor from both direction during earthquake.
All hope is not lost in the quest to construct buildings that can resist earthquakes for example, the Transamerica Pyramid Building located in San Francisco was constructed with earthquake resistant technology and it has already swayed and moved a foot up during the 1989 earthquake and it never gave in. In the Himalayas, there are many buildings that have resisted earthquake over the years. These structures were built with local raw materials like woods, clay slabs, stones and slabs. Some of these building are standing at eight meters above ground levels, others are five to six storeys tall with rooms on each floors. These traditional structures have over the years stood the test of time against earthquake.
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