Earthquake-resistant structures and structural elements generally feature ductility (a building's capacity to bend, sway, and deform without collapse). When subjected to horizontal or vertical shear stresses from an earthquake, a ductile structure can bend and flex. The amount of bending depends on the strength and length of the member in question. Long, slender members such as trusses and girders tend to bend more than thick ones such as beams. Earthquake-resistant structures also tend to be rigid; that is, they do not sway greatly in response to an earthquake. This reduces damage caused by high winds after an earthquake.
Durable materials used in construction, such as steel and concrete, are important for making structures earthquake-resistant. Concrete frames with internal steel reinforcement are commonly used to build very strong houses. These houses typically cost more but are less likely to collapse during an earthquake.
Other factors affect how well a building stands up to an earthquake. For example, the location of a house within an area prone to earthquakes will determine how safe it is. If a house is close to the ground level or not located on solid ground, it is at risk of collapsing during an earthquake. A good building code should specify minimum requirements for resistance to earthquake forces.
Concrete buildings, which are generally brittle (easy to shatter), may be made ductile by reinforcing them with steel. The key is to avoid placing the fibers in tension, which will cause them to break.
Concrete has been used as a building material for thousands of years because of its ease of construction and low cost. It is also widely considered to be environmentally friendly because of its natural composition and its potential to reduce our dependence on oil for fuel.
However, like any other material, concrete can fail under certain conditions. Concrete buildings suffer damage when their structural elements such as beams and columns become detached from each other. This can occur if an intense force acts on one part of the building while another part remains standing. In this case, the detached element will fall under its own weight until it hits something that prevents it from falling any further. This something can be another detached element or the ground.
The strength of concrete depends on several factors such as the type of aggregate used, the ratio of cement to water, and the duration of the mixing process.
The term "ductility" refers to a material's ability to withstand massive deformations. Steel-reinforced concrete is one of the finest earthquake-resistant construction materials because the steel inserted enhances ductility. The word "seismic" means the ability of a structure to resist damage from an earthquake.
Other common engineering materials used in construction are aluminum, plastic, and wood. Each has its advantages and disadvantages with respect to cost, durability, weight, flexibility, and resistance to fire or other hazards. Of these, the most important consideration in selecting a material for an earthquake-prone area is its resistance to rupture during an earthquake. In other words, you want something that will not break easily under stress. Plastic and wood tend to fail first during an earthquake, while steel remains rigid and fails only after some degree of deformation has been achieved. Concrete, due to its ability to absorb energy through stretching and compression of its microstructure, is commonly selected as the primary support member within an earthquake-resistant framework. It provides rigidity against which steel and other materials can be attached. Concrete also functions as a protective barrier between the internal parts of a building and any moving furniture or equipment within the structure.
Earthquake protection involves more than just constructing a strong foundation. You also need to think about how objects in your home function during an earthquake.
Materials for Long-Lasting Construction These materials are very ductile and can withstand massive deformations without failing. Because of this feature, these materials are perfect for the building of earthquake-resistant homes that must survive strong ground tremors. Steel and concrete are the most common choices for the framing material for high-quality buildings. Concrete frames are the most affordable but also the least durable because they have a low iron content and so are highly vulnerable to corrosion. Steel frames are the most durable but also the most expensive because they require careful fabrication and extensive post-construction maintenance to prevent rusting. Brick and stone are also good options for framing materials because they are durable, attractive, and relatively inexpensive. However, they cannot be used alone as the primary support structure because they have insufficient mass per unit area to resist collapse during an earthquake.
The best option for housing in earthquake-prone regions is the use of seismic design standards by all code officials in place to ensure maximum effectiveness of the available technology applied to new construction. Seismic design involves the use of detailed drawings that show where and how elements of the house should respond to an earthquake.
Earthquake-resistant building designs take into account the following structural integrity factors: stiffness and strength; regularity; redundancy; foundations; and load routes. Stiffness and strength are related to the material used to build the structure. Regularity refers to how often components such as beams and columns are spaced throughout the building. Redundancy is the use of multiple components to ensure that a structure will remain standing even if some of its parts fail. Foundations can affect whether a building remains standing after an earthquake. Load routes indicate the path or channel through which forces are transmitted from one part of the building to another.
Buildings can be designed to be more or less earthquake resistant. A highly resistant building would need much thicker walls and floors to achieve the same level of protection as a moderately resistant building. Also, extremely resistant buildings would not be able to accommodate furniture or other movable objects that could interfere with emergency escape routes in case of an earthquake.
Moderately resistant buildings should have strong floor plans with wide open spaces to allow easy egress in case of an emergency. They also should include fire extinguishers in all rooms and smoke detectors near sleeping areas.
Weakly resistant buildings require only thin walls and floors and could possibly have furniture in them.
To obtain the appropriate ductile behavior in buildings constructed using steel-reinforced concrete, both the steel and the concrete must be properly made. Building breakdowns during earthquakes are frequently caused by faulty building practices or insufficient materials. To prevent this from happening, all structural components should be designed for high seismic activity areas. This includes columns, beams, and floors.
The quality of concrete used in construction has a great impact on how well it will perform under stress conditions. High-quality concrete is strong when fresh, but also durable over time. It can with stand the forces that occur during an earthquake without breaking down. Concrete that is not of high quality may contain excess air in its structure, which increases its risk of failure during an earthquake. The more frequent it is cleaned, the longer it will last before requiring replacement.
Steel reinforcement in concrete structures prevents the concreted mixture from collapsing after it has set. The steel bars should be embedded in the concrete to ensure maximum strength and durability. The type of steel used to reinforce concrete structures affects their ability to withstand compression or tension loads. For example, if concrete is reinforced with 18-gauge wire, it will be stronger than concrete reinforced with 16-gauge wire.
Buildings can be strengthened by using special techniques during construction or after completion.