Natural disasters tend to have significant implications. These include collapsing of buildings, which translate to loss of life and destruction of property worth a lot of money. Natural disasters include earthquakes, floods, volcanoes, and extreme weather conditions such as hurricanes, lighting, storms, and mass movements. Each of these natural disasters requires the design of the building to incorporate an element or a factor, which avoid or reduce the impact of the natural disaster or how it will resist the natural disaster. In the design of buildings, earthquakes are of significant importance since they result to a lot of damage in structures and buildings. Earthquakes tend to have the most significant impact on buildings and structures. Engineers are tasked with the responsibility of ensuring that buildings adhere to structural integrity standards. Increasing concentration of seismic activity over the last decade has increased the vulnerability of certain buildings that were designed in the 20th century. The materials and the design of the building are critical to ensure the resistance of the building to earthquakes (Office of Technology Assessment, 1995). The building construction should be equipped and prepared to resist earthquake, floods, and hurricanes.
One of the new technologies being employed to increase the resistance of buildings to earthquakes is base isolation. According to the Office of Technology Assessment (1995), the use of base isolation allows the building to be separated from the ground. Therefore, the ground beneath the build can move, but the building itself does not move. According to McDonald (2012), base isolation lengthens the period of the building’s superstructure to almost 2 seconds. This becomes useful in the design of buildings where the interior components require minimum disturbance, for instance laboratories and hospitals. This method is implemented by using rubber and steel pads bearings between the building and the ground. Additionally, base isolation can be effected by using a bearing and concave surface, where the columns of the building are connected to a bearing that is rested on a concave surface. During an earthquake, the concave surface will slide, as the building remains immobile. Further, use of active control systems becomes beneficial in minimizing the earthquake damage to buildings. In case of an earthquake, the active control systems detects the earthquake and may respond by causing the building to shift in such a way that in counters the movement caused by the earthquake. An example of the application of active control systems is the use of a large weight on the apex of a building, which is computer controlled to shift in such a way as to resist the earthquake sway induced on the building (Office of Technology Assessment, 1995). Passive energy dissipation system may also be used in resisting building drifts (McDonald, 2012). Mass movements beneath the surface of the earth may cause stress on the foundation of a building. The passive energy dissipation system slows down the drift of a building using devices that dissipate the energy of the earthquake through friction. According to McDonald (2012), a material used for this purpose is the magnetorheological fluid. This fluid converts to a solid phase when subjected to magnetic forces and returns to a liquid phase when the force is removed. This fluid can be employed in buildings, bridges, and elevated highways. Increasing the resistance of existing building to earthquakes may require the use of bracing. Further, the connections of the walls and the floors can be improved, where structural framing is added to the exterior walls to increase their strength (Office of Technology Assessment, 1995).
Floods will affect buildings and water retaining structures such as dams. Constructing of structures such as diversions, channels and impoundments also serve to reduce the impact of flooding. The design of water retaining structure needs the capacity of the dams to be designed for the extreme case of flooding (Wilby and Keenan, 2012). Currently, because of the increase changes in climate, the design of these structures need to be designed incorporating a climate change factor (Wily and Keenan, 2012). Further, for the existing flood defense structures, upgrading is required to ensure the performance of these structures is maintained. Residential buildings constructed in flood prone areas should have the basement elevated above the base flood elevation (FEMA). Further, the construction of certain structures such as solid perimeter walls and garages attached to elevated buildings will require designing of flood openings. In the flood hazard areas of rivers, it is recommended to construct open foundations because of the likelihood of experiencing debris loads. Building of solid foundations in these areas may damage the perimeter walls despite the provision of flood openings. In designing buildings to resist floods, significant issues to include should address elevation of structures, building with materials that get wet and using design assemblies that easily dry when they are wet. Further, parts of the building such as the connectors and fasteners need to be made of material that is resistant to flood damage. Flood damage resistant materials include glazed brick, glass block, and use of water resistant glue, metal doors, and windows. Additionally, foundations and other equipment that are positioned below the flood protection level need to be anchored firmly to prevent lateral movement and collapse. Drainage is crucial in the construction of roads. The design of roads should ensure sufficient drainage is provided in areas where runoff is easily generated. High runoff areas require a significant number of culverts to be constructed on the road.
Constructing structures to resist hurricanes requires engineers to consider the structural configuration of the building. In areas prone to frequent hurricanes, the height of the buildings needs to be limited to two storeys (Gibbs, 2000). Additionally, the roofs and the lightweight floors need to be tightly connected to the walls to increase their resistance to the hurricane (Gibbs, 2000). Further, to ensure stability of the building, the shape of the building needs to be symmetrical. This ensures that there is equal distribution of forces in the whole structure or building. According to Gibbs (2000), using lightweight roofs will require the slopes to be more than twenty degrees to increase their resistance. Moreover, the roofs need to be sloping in four directions and not in two directions to increase their resistance to the hurricanes. Gibbs (2000) discourages the use of overhangs, which reduce the resistance to hurricanes. The use of a ridge ventilators minimize the internal pressures, which assist in holding the lightweight roofs during the hurricane. Vulnerability of structures such as pipelines that may be installed on the ground surface has a high chance of being affected by weather conditions such as hurricanes. In an area where hurricanes are predicted to be frequent, the above ground lines can be constructed below the surface to reduce their exposure (Lindlee, Prater, and Perry, 2006). Tall buildings are more likely to be affected by the impact of strong winds and hurricanes. The building design codes need to be adjusted to take into account the worst-case scenario. That is the wind-loading factor needs to be inclusive of the highest possible wind or hurricane speed.
Destruction of buildings and structures following natural disasters causes loss of lives and damage to property worth millions and billions. Different natural disasters tend to have different effect or damage on buildings. As discussed, earthquakes tend to have or play an influential part in the design of buildings and other structures. This is because they earthquakes tend to have an impact on the foundation of structures where all loads on a building are transferred. In flood prone areas, structures should be designed based on the set building codes in that area. Engineers need to use flood damage resistant materials in the construction of the buildings. It is advisable in hurricane prone areas to construct short buildings. Engineers need to ensure that structures constructed are symmetrical in shape and the roofs slope at an angle between twenty and thirty degrees to increase the resistance of the roof to the hurricane. Design of tall building requires the application of factor of safety for wind loads depending on the wind speeds for the specific areas.
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