The article "Stubborn Structures" from the University of Michigan's Department of Engineering emphasizes that steel is ductile and absorbs energy, but concrete, when reinforced with steel, is strong in terms of tensile and compression. The combination of these two materials is what makes some structures vibration-resistant.
Buildings can be designed to be resistant to earthquakes. When a powerful earthquake strikes an area where many buildings have not been well constructed, many suffer severe damage or collapse. But for those who were built correctly, they remain standing. The reason for this difference? Well-designed buildings use materials that are appropriate for their purpose. Concrete frames covered with brick or stone facades or panels are extremely resistant to damage caused by an earthquake. Steel frames with glass facades are more flexible and less likely to cause serious injury if an earthquake does occur. However, even if a building collapses, its contents will be protected because most goods stored in open shelves or units are not tied down.
The design of a building site also affects how much damage it causes during an earthquake. Areas where soil is soft and poorly drained are more likely to cause damage during an earthquake because water can accumulate in low-lying areas and cause structural damage over time. If a building is located on such land, it should be designed to withstand high loads due to precipitation.
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, zinc, and wood. Each has its advantages and disadvantages with respect to cost, durability, weight, and ease of use. For example, aluminum frames are light and easy to manufacture, but they're also relatively expensive. Wood is a popular choice among homeowners who want their buildings to be environmentally friendly, but it can be difficult to find lumber that's strong enough for high-rise building projects.
Concrete is by far the most commonly used earthquake-resistant material. Concrete structures can absorb some of the force of an earthquake, reducing the amount of energy that reaches the building's foundation. In addition, concrete can help prevent more serious damage to buildings by absorbing some of the shock waves created during an earthquake.
When choosing how to protect your building against earthquakes, consider how severe the earthquake will be, where it will be located, and what kind of damage you want to avoid. An understanding of these factors will help you choose the right method of protection for your building.
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 poor construction practices or insufficient materials. To prevent this from happening, high-quality construction materials are required, and building codes should be strictly followed.
The main components of earthquake resistant buildings are:
Steel frames with rubberized asphalt coating to protect them from rusting - these days they are usually also insulated with polystyrene foam or other insulating materials.
Concrete with high-quality aggregate and cement that can resist compression forces - for example, granite dust aggregates are very strong but also very heavy, so lighter alternatives such as quartz powder or crushed glass are being used more often these days.
Laminated beams - thick layers of wood or metal attached at right angles with adhesive - these are used instead of solid beams when greater strength is needed.
Rebar - long rods of steel wire with plastic or paper coverings on both ends - these are used as reinforcement in concrete structures to improve its strength and stability.
Shims - small pieces of wood or metal used to evenly distribute pressure across a structure so it does not break down under weight loads.
When subjected to horizontal or vertical shear stresses from an earthquake, a ductile structure can bend and flex. Concrete buildings, which are generally brittle (easy to shatter), may be made ductile by reinforcing them with steel. The primary method of earthquake resistance for concrete structures is through the use of reinforcement. Reinforcement can be in the form of wires inserted into the concrete during its construction or later added materials such as fibers or rods. The effectiveness of this method depends on how much stress results from an earthquake. If the load resulting from an earthquake is spread out over a large area, then the force per unit area on the concrete is low, and the building will not be damaged.
The main types of reinforcement used in concrete structures are rebars (bars) and prestressing cables. Rebar is any of various long, slender elements used to reinforce concrete. The two most common types are straight bars and wire mesh. Straight bars are most commonly found inside concrete walls where they act to prevent the wall from collapsing during an earthquake. Wire mesh is used primarily for concrete roofs because it allows water to flow through while preventing larger objects such as gravel from entering the concrete slab.
Prestressing cables are strands of high-strength wire that are wrapped around a drum before being coated in plastic material. The ends of each cable are then tied off so that only one end is exposed.