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Tornadoes, cyclones, and other storms with strong winds damage or destroy many buildings. However, with proper design and construction, the damage to buildings by these forces can be greatly reduced. A variety of methods can help a building survive strong winds and storm surge.
Waves along coastal areas can destroy many buildings. Buildings should preferably be built on high ground to avoid waves. If waves can reach the building site, the building should be elevated on steel, concrete, or wooden pilings or anchored to solid rock.
Wind on the roof surfaces can cause negative pressures that create a lifting force sufficient to lift the roof off the building. Once this occurs, the building is weakened considerably, and the rest will likely fail as well. To minimize this vulnerability, the upper structure ought to be anchored through the walls to the foundation.
Several methods can be used to anchor the roof. Typically, roof trusses are "toenailed" into the top of the walls, which provide insufficient force to resist high winds. Hurricane ties nail into the wall and wrap over the trusses to provide higher force resistance.
Interlocking metal pan roof systems installed on mobile homes can fail under the pressure differential (lift) created by the high-velocity winds passing over the surface plane of the roof. This is compounded by the wind entering the building allowing the building interior to pressurize, lifting the underside of the roof panels, resulting in the destruction of the building. One example of pan roof systems can be found in this document from Structall Building Systems Archived 2016-03-04 at the Wayback Machine .
To mitigate this pressure differential, pre-installed aluminum tabular channels can be permanently fastened perpendicularly across the top of the interlocking ribs of the metal roof system without disturbing the flow of rainwater at the eaves mid-span and ridge locations of the building.
Earth-sheltered construction is generally more resistant to strong winds and tornadoes than standard construction. Cellars and other earth-sheltered components of other buildings can provide safe refuge during tornadoes.
The physical geometry of a building affects its aerodynamic properties and how well it can withstand a storm. Geodesic dome roofs or buildings have low drag coefficients and can withstand higher wind forces than a square building of the same area. [1] [2] Even stronger buildings result from monolithic dome construction. [3]
A Category 5 hurricane-proof log house is resistant to winds up to 245 miles per hour (394 km/h). Wall logs in such construction must be made of glued laminated timber and all other components of the house, including hurricane straps, must be hurricane-resistant.
A round, or multiple-sided home, is more resistant to hurricane strength winds. [4] [5] The round design allows the wind to blow around the home, reducing the build-up of pressure on one side. [6] Additionally, with the roof and floors built using a radial truss array, that allows any potential energy from sustained winds to disperse across the entire structure instead of building up in one area. [7]
Building openings such as garage doors and windows are often weak points susceptible to failure by wind pressure and blowing debris. Once failure occurs, wind pressure builds up inside the building resulting in the roof lifting off the building. Hurricane shutters can provide protection.
Doors can be blown into the house by wind, causing potential structural failure (see http://www.floridadisaster.org/hrg/content/openings/openings_index.asp#Hinged_Exterior_Doors).
Windows can be constructed with plastic panes, shatterproof glass, or glass with protective membranes. The panes are often more firmly attached than normal window panes, including using screws or bolts through the edges of larger panes. Concrete anchor screws are used to secure windows to the concrete structure surrounding them.
Wood has a relatively high degree of flexibility, which can be beneficial under certain building stresses.
Reinforced concrete is a strong, dense material that can withstand the destructive power of very high winds and high-speed debris if used in a building that is designed properly.
After Hurricane Andrew in 1992 caused $16 billion in insured damage, the state of Florida established new building standards and enforcement. The state increased performance criteria for wind-load provisions and adopted new wind provisions from the American Society of Civil Engineers. One important addition to the new code was the requirement of missile-impact resisting glass, which can withstand high-velocity impact from wind-borne debris during a hurricane. Many houses built in South Florida since Hurricane Andrew are cinder block masonry construction reinforced with concrete pillars, hurricane-strapped roof trusses, and codes requirements for adhesives and types of roofing. [8] [9] Florida also designated high velocity hurricane zones (i.e. High Velocity Hurricane Zone) with special requirements defined for Miami-Dade and Broward Counties. [10]
Hong Kong requires many structures to withstand winds from typhoons. [11]
Residential construction in Darwin Northern Australia
An earth shelter, also called an earth house, earth bermed house, or underground house, is a structure with earth (soil) against the walls, on the roof, or that is entirely buried underground.
The Saffir–Simpson hurricane wind scale (SSHWS) classifies hurricanes—which in the Western Hemisphere are tropical cyclones that exceed the intensities of tropical depressions and tropical storms—into five categories distinguished by the intensities of their sustained winds. This measuring system was formerly known as the Saffir–Simpson hurricane scale, or SSHS.
Retaining walls are relatively rigid walls used for supporting soil laterally so that it can be retained at different levels on the two sides. Retaining walls are structures designed to restrain soil to a slope that it would not naturally keep to. They are used to bound soils between two different elevations often in areas of inconveniently steep terrain in areas where the landscape needs to be shaped severely and engineered for more specific purposes like hillside farming or roadway overpasses. A retaining wall that retains soil on the backside and water on the frontside is called a seawall or a bulkhead.
Earthbag construction is an inexpensive building method using mostly local soil to create structures which are both strong and can be quickly built.
A curtain wall is an exterior covering of a building in which the outer walls are non-structural, instead serving to protect the interior of the building from the elements. Because the curtain wall façade carries no structural load beyond its own dead load weight, it can be made of lightweight materials. The wall transfers lateral wind loads upon it to the main building structure through connections at floors or columns of the building.
Seismic retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion, or soil failure due to earthquakes. With better understanding of seismic demand on structures and with recent experiences with large earthquakes near urban centers, the need of seismic retrofitting is well acknowledged. Prior to the introduction of modern seismic codes in the late 1960s for developed countries and late 1970s for many other parts of the world, many structures were designed without adequate detailing and reinforcement for seismic protection. In view of the imminent problem, various research work has been carried out. State-of-the-art technical guidelines for seismic assessment, retrofit and rehabilitation have been published around the world – such as the ASCE-SEI 41 and the New Zealand Society for Earthquake Engineering (NZSEE)'s guidelines. These codes must be regularly updated; the 1994 Northridge earthquake brought to light the brittleness of welded steel frames, for example.
Hurricane coverings, commonly known as shutters, are used in hurricane mitigation to protect houses and other structures from damage caused by storms. Hurricane shutters are used to prevent windows from being broken by flying objects during a storm. Although the negative pressure caused by high-speed wind flowing over a building roof can cause the roof to fail with the building envelope intact, broken windows allow the air pressure to rise inside a building, creating an even greater pressure difference and increasing the likelihood of roof failure.
A concrete block, also known as a cinder block in North American English, breeze block in British English, concrete masonry unit (CMU), or by various other terms, is a standard-size rectangular block used in building construction. The use of blockwork allows structures to be built in the traditional masonry style with layers of staggered blocks.
This page is a list of construction topics.
Waterproofing is the process of making an object, person or structure waterproof or water-resistant so that it remains relatively unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in wet environments or underwater to specified depths.
A tie, strap, tie rod, eyebar, guy-wire, suspension cables, or wire ropes, are examples of linear structural components designed to resist tension. It is the opposite of a strut or column, which is designed to resist compression. Ties may be made of any tension resisting material.
Steel frame is a building technique with a "skeleton frame" of vertical steel columns and horizontal I-beams, constructed in a rectangular grid to support the floors, roof and walls of a building which are all attached to the frame. The development of this technique made the construction of the skyscraper possible. Steel frame has displaced its predecessor, the iron frame, in the early 20th century.
Formwork is molds into which concrete or similar materials are either precast or cast-in-place. In the context of concrete construction, the falsework supports the shuttering molds. In specialty applications formwork may be permanently incorporated into the final structure, adding insulation or helping reinforce the finished structure.
Cyclone mitigation encompasses the actions and planning taken before a tropical cyclone strikes to mitigate damage and injury from the storm. Knowledge of tropical cyclone impacts on an area help plan for future possibilities. Preparedness may involve preparations made by individuals as well as centralized efforts by governments or other organizations. Tracking storms during the tropical cyclone season helps individuals know current threats. Regional Specialized Meteorological Centers and Tropical Cyclone Warning Centers provide current information and forecasts to help individuals make the best decision possible.
Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast beams, and wall panels for tilt up construction. In contrast, cast-in-place concrete is poured into site-specific forms and cured on site.
Domestic roof construction is the framing and roof covering which is found on most detached houses in cold and temperate climates. Such roofs are built with mostly timber, take a number of different shapes, and are covered with a variety of materials.
A safe room or panic room is a fortified room that is installed in a private residence or business to provide a safe shelter, or hiding place, for the inhabitants in the event of a break in, home invasion, tornado, terror attack, or other threat. Safe rooms usually contain communications equipment, so that law enforcement authorities can be contacted.
A windstorm inspection, also referred to as a windstorm mitigation inspection, windstorm insurance inspection or wind mitigation inspection, is a kind of home inspection common in the coastal areas of the Southeastern United States. The purpose of a windstorm inspection is to determine the appropriateness of a given structure's construction in the event of strong winds, such as those present in a hurricane.
A hip roof, hip-roof or hipped roof, is a type of roof where all sides slope downwards to the walls, usually with a fairly gentle slope. Thus, a hipped roof has no gables or other vertical sides to the roof.
A windpost is a structural item used in the design and construction of masonry walls to increase lateral wall stability and protect them against damage from horizontal forces imposed by wind pressure, crowd or handrail loads. They are normally constructed from mild steel channel sections, supported at the head and the foot between floor slab levels and/or the principal steelwork sections forming the structural frame of the building. In cavity walls, the windpost will typically be fixed into the inner and outer leafs of the wall by specialist fixings and fastenings at regular intervals along its length. The windposts will be spaced along the walls of the building at regular intervals as calculated by the engineer to suit the required loadings.
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