How To Design Building Structures That Can Survive Earthquakes
Earthquakes are natural disasters where most of damage is caused due to collapse of buildings and other such man-made structures. Earthquakes do not kill people, buildings do. Buildings that lack structural stability collapse and they cause irreparable damage to life and property.
Why Buildings Fail During Earthquakes
When an earthquake happens, the ground shakes, and all the buildings respond to these vibrations and tremors, at varying degrees. Greater mass and exertion of more lateral force on buildings is scientifically why buildings get damaged during earth quakes.
However in structures that are erected using poor quality building materials and when engineering principles are not applied in order to build strong and stable structures – the damage is more lethal.
During an earthquake, the lack of strong joint components like walls, roof, slabs, beams and columns in the building, causes the structural elements to move independently in any direction and the velocity of these movements depends on their weight and orientation. This causes the elements to separate from each other, the building disintegrates and collapses.
What is Earthquake Resistant Architecture?
An earthquake resistant architecture talks about a building design that can withstand the turmoil inside the Earth and the resulting vibrations. To be more precise, a structure that is capable of exhibiting a seismic resistant capability during the ground shake is an earthquake resistant structure.
It’s important to understand what seismic intensity zone the building you are going to erect falls under, and its structural design needs to be developed accordingly.
Recently there have been instances where earthquakes have literally razed cities. However adopting to some basic principles of construction can make cities more resistant and help them survive earthquakes.
Earthquake resistance can be achieved by following good construction practices, and adhering to rules and building standards- these might not completely prevent damage to the buildings during ground shake, but will definitely prevent buildings from collapsing and causing damage to life and property.
To introduce seismic resistance at economical costs, three parameters are of crucial importance. They are:
- Seismic intensity zone of the building
- The functional properties of the building
- Bearing capacity of foundation soil
In addition to these considerations implementing certain measures while construction planning and design can help build a structurally strong and stable building. These measures include:
- A free standing wall that behaves as a vertical cantilever should be designed. This might be difficult for unreinforced masonry; hence all partitions in the building must be secured from the sides and the top. Parapets must be reinforced and secured to the main structural frames and slabs.
- Walls should be horizontally reinforced so that the out of plane inertia load is transferred horizontally to the Shear walls.
- Walls should be tied together structurally so that they can resist ground shake and do not disintegrate or separate at the vertical joints, when under the influence of such tremors and vibrations.
- Shear walls must be kept along both axes of the building, and should be designed to resist all horizontal forces that are transmitted to it.
- Roof and floor elements should also be structurally bound to improve their capability of diaphragm action.
- Trusses must also be anchored to support the walls such that they transfer their inertia force to the end walls.
- Over and above when planning and layout design for a building is done, at this time in addition to demarcation of rooms and walls, design of openings such as windows and doors, number of floors etc. site and foundation aspects should also be considered.
The structural framing system should be designed with special attention to the furnishing of lateral resistance and critical sections that are meant to be highly loaded should be given special consideration and reinforcement as required should be provided.