An Analysis of Formatic Modulation and Demand of High Rise Structures

An Analysis of Formatic Modulation and Demand of High Rise Structures

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High Rise Structures

The statistics from Indian Government says that the area of the country is about 3,287,590 sq.km and the population about 1,250,193,422. This makes land resource very precious to the India. A high-rise structure can provide space and work for people in such a case. A high-rise is just a tall structure. They first became possible due to the invention of the elevator and a cheap building material. Reinforced concrete and steel are used for their structural system. Steel Frames are used for most American style skyscrapers and concrete for residential tower blocks. A skyscraper is a very tall, continuously habitable building. For a building to qualify as a skyscraper, a height of approximately at least 150 meters or 500 feet is often used as a criterion. Other criteria to affect the decision are shape and appearance. Chicago is credited as the birthplace of the skyscraper. High-rise structures are also called “vertical cities”, having the potential to decongest urban sprawl. Indian cities are witnessing immense demographic expansion due to migration from surrounding villages, leading to urban sprawl, housing demand, rise in cost of land. Housing has developed into an economy generating industry.

The normal storied buildings and high rise buildings are very different. So, the activities involved starting from the planning stage will impact the completion of the project. It will require planning of urban infrastructure around the structure. A detailed planning will be required for the building services and utilities in all the stages of construction. The safety requirements, the management requirement all increases drastically. Other factors that favour this are: 1. Rapidly growing urban population that increased demand for tall buildings 2. At the expense of quality of life, the human factors being neglected. 3. To establish priorities for new research in this particular field. 4. The professionals.

High Rise Structures in India

Indian cities are witnessing immense demographic expansion due to migration from surrounding villages, leading to urban sprawl, housing demand, rise in cost of land. Many citizens all over India migrate to the cities for better jobs and education. Industries, trade and commerce activities and number of educational centres in cities attract floating population from all their surrounding villages and districts. This has expanded the cities in all directions and all aspects of development. With an urban sprawl of kilometres, these face the problems of congestion, pollution, everyday commuting to workplace, competition, deforestation etc.

The development can be categorized in four categories considering different philosophy: High Rise with High Density; High Rise with Low Density; Low Rise with High Density; and Low Rise with Low Density. In India, a building greater than 75 ft (23 m), generally 7 to 10 stories, is considered as high-rise. Also a building is considered to be high-rise when it extends higher than the maximum reach available to firefighters. According to the building code of India, a tall building is one with four floors or more or a high-rise building isone 15 meters or more in height. Most of the tall buildings in India are in the commercial capital Mumbai. More than 2500 high-rise buildings are already constructed. In addition more than thousand mid-rises exists already in the city. Mumbai is undergoing a massive construction boom, with thousands of tall buildings and about fifteen high-rise structures are under construction. Delhi and its surrounding regions are witnessing huge construction activities with 1500 already constructed high-rises.

 

 

Load System:

Loads that have to be taken into consideration when designing a building are vertical loads from self-weight, imposed loads, snow loads and horizontal loads from both wind and unintended inclinations. For tall buildings, as earlier mentioned, the horizontal loading from wind is usually the design load. Tall buildings are subjected to various types of loads during its service lifetime. It must be so designed to resist the gravitational and lateral forces, both permanent and transitory, that will be called on to sustain during its construction and subsequent service life. Major loads of which tall building structures ar :Vertical Loads: Dead loads arise from the weigh to the individual construction elements and the finishing loads. Live loads are dependent on use depending on the number of stories; live loads can be reduced for load transfer and the dimensioning of vertical load-bearing elements.

Horizontal Loads: It generally arises from unexpected deflections, wind and earthquake load

Unexpected Deflections: It arises from imprecision in the manufacture of construction elements and larger components.

Wind Loads: High-rise buildings are susceptible to oscillation. It should not be viewed as statically equivalent loads but must be investigated under the aspect of sway behavior. Earthquake Loads. It travels through rock, and provide an effective way to image both sources and structures deep within the Earth. Produce different types of seismic waves.

Seismic Waves: There are three basic types of seismic waves in solids: P-waves, S-waves, P-and/or S-waves and two basic kinds of surface waves (Raleigh and Love).

Pressure waves/Primary waves /P-waves-P-waves are fundamentally pressured disturbances that propagate through a material by alternately compressing and expanding (dilating) the medium, where particle motion is parallel to the direction of wave propagation.

Shear waves/secondary waves/S-waves: Transverse waves that travel more slowly than P-waves and thus appear later than P-waves on a seismogram.

Structural Forms Systems for Tall Building Structures

Braced-Frame Structural System: This system is used in steel construction, it is both an efficient and economical way for improving the lateral stiffness and resistance of rigid frame system. The bracing will almost eliminate the bending of columns and beams by resisting lateral loads primarily through axial stress, thus allowing for slenderer elements. A very well known example of braced frame structural system can be seen in the Empire State Building.

Framed Tube Structural System: The ‘tube’ system evolved from a quest to develop a bracing configuration that would place as much gravity load on the exterior columns as possible to help counter the overturning effects of lateral loads while taking advantage of exterior column’s large distance to the neutral axis to resist bending moment. The solution was to create a system in which the exterior frames encircling the structure would be rigid enough to behave as nearly as possible like a three-dimensional vertical cantilever. A well-known example of framed tube structural system is World Trade Center which is 110 stories high structure.

Outrigger-Braced Structural System: Outrigger is rigid horizontal structures designed to improve building overturning stiffness and strength by connecting the core or spine to distant columns. Outrigger systems function by tying together two structural systems- typically a core system and a perimeter system to yield whole structural behaviors that are much better than those of component system. The benefits of an outrigger system lie in the fact that building deformations resulting from the overturning moments get reduced, on the other hand, greater efficiency is achieved in resisting forces.

Shear Wall Structural System: Concrete or masonry continuous vertical walls may serve both architecturally as partitions and structurally to carry gravity and lateral loading. Their very high in-plane stiffness and strength make them ideally suited for bracing tall building structures. Because of their stiffness, shear wall structural system can be economical up to 35 stories building structure. Shear walls are usually provided along both length and width of buildings. Shear walls are like vertically-oriented wide beams that carry earthquake loads downwards to the foundation. Such a wall acts as a beam cantilevered out of the foundation and just as with a beam, part of its strength derives from its depth.

Rigid Frame Structure: This system Consist of columns and girders joined by moment-resistant connections. Ideally suited for reinforced concrete buildings because of the inherent rigidity of reinforced concrete joints. Also used for steel frame buildings, but moment-resistant connections in steel tend to be costly.

In-filled Frame Structure: The Most usual form of construction for tall buildings up to 30 stories in height Column and girder framing of reinforced concrete, or sometimes steel, is in-filled by panels of brickwork, block work, or cast-in-place concrete.

Flat-Plate and Flat Slab Structure: Is the simplest of all structural forms in that it consists of uniforms slabs, connected rigidly to supporting columns. Particularly appropriate for hotel and apartment construction where ceiling space is not required and where the slab may serve directly as the ceiling. Economic for spans up to about 25 ft (8m), above which drop panels can be added to create a flat-slab structure for a span of up to 38 ft (12m).

Coupled Wall Structure: This system consists of two or more shear walls in the same plane, or almost the same plane, connected at the floor levels by the beam or stiff slabs. Suited for residential construction where lateral-load resistant cross walls, which separate the apartments, consist of in-plane coupled pairs, or trios, of shear walls between which there are corridor or window openings.

Wall-Frame Structure: The walls and frame interact horizontally, especially at the top, to produce stiffer and stronger structure. The interacting wall-frame combination is appropriate for the building in the 40 60 story range, well beyond that of rigid frames or shear walls alone.

Hybrid structure: Hybrid structures are often used for a non-prismatic structure where two or more of the basic structures described earlier are used in the same building. This concept can be used for either direct combination of, for example, a tube and an outrigger system or by adopting different systems for different parts of the building, for example, a tube system on three walls and a frame on the fourth wall.

Construction Techniques for High Rise Building:

In terms of technology, there are certain crucial guidelines when planning the tall building”. Many high rise building are being constructed in India in which different latest technology are used for construction and also the concept of green technology are being updated. Steel technology and reinforce cement concrete are mostly used for the construction of the high rise building. The high strength cement are being used for the high rise building construction as then the ordinary cement. In most of the high rise building the cement blocks are being used for the walls construction. The different machine are being used for the easy construction of high rise building. The ready mix concrete are being used. The machine like vdf (vaccum dewatered flooring) which is used for the smoothing of the surface are used. Different architectural concept are being applied for the construction. Drywall techniques is easier, faster and more economical compared to the traditional technology of hand plastering. Different ground improvement techniques are being used for the stability of soils. The geosynthetics materials are also being used to give the more strength to the soil and also to the building. The construction of the high rise building is going on and the construction technology that are being applied for the high rise building is also improving. To stop the leakage problem they are applying the low roof in the bathroom and also to maintain the water pressure the diameter of different pipeline are being applied according to the building height. hope in future the latest techniques will be invented for the construction of the high rise building with a good strength.

Materials Used in the Construction of High-Rise Buildings in India

Concrete is an incredibly strong man made mixture of aggregate (sand and gravel), cement and water that has been used in construction since Roman times. It is very hard and in its normal state can withstand high compressive loads but it has one major weakness – it cannot resist tension loads. Many factors will affect how concrete will behave under fire conditions. These may include: Quantity and type of aggregate used in the mix Thickness (and thus protection of reinforcement) Type of Cement used Water content of the concrete Load bearing Fire Exposure time Temperature Application of water (fire fighting Jets) Cladding or covering Age The failure of the concrete slab usually occurs in the form of spalling which is the progressive deterioration of the surface exposed to heat. This is because the aggregate element usually contains quartz, which will start to crack and disintegrate at 600oC. It is the type and quantity of aggregate in the concrete mix that will define its inherent fire behavior of concrete in fire resistance properties. Steel is extensively used in all forms of construction and is present in nearly every form of reinforced concrete. Steel is a metal alloy whose major component is iron. Carbon is added and this acts as a hardener. Because of its limitations in fire, if used in a structural context, steel is usually given additional fire protection, in the form of a sacrificial cladding or a barrier. The steel work buried within reinforced concrete is to a large degree protected from fire by the concrete covering it, but prolonged exposure to high temperature can affect the integrity or the tensioning within concrete, leading to failure. High strength and the development of modern glass construction techniques means that many new high rise buildings use large quantities of glass as walling (usually supports by steel framework). This technique is seldom used in residential accommodation, but all windows are of glass held in by a variety of framing materials. Aluminum is a relatively soft and light metal with a melting point of 660oC. Its lightness means it has uses in the construction industry for non-structural items, such as door and window frames and external cladding. It is important to note that exposure to high temperatures will lead to early failure and if these frames form part of the fire resistance of the building (either compartmentation within lobby’s or as windows between floors) integrity can be affected. Aluminum as an external cladding can melt if exposed to fire and the falling molten aluminum possess additional hazards.

In India, coal will continue to remain a major source of fuel for power generation. At present, about 60% power is produced by using coal as fuel, which results in the production of about 112 million tons of fly ash per annum. Considering the tremendous growth required in the power sector for the development of Indian economy, it is expected that ash generation will reach 225 million tons by 2017. Ash is good resource material for utilization in various areas such as manufacture of cement, cement concrete, embankment construction, low lying area filling etc.

Demand of High Rise Building in India:

Due to the over crowded of population and also the pollution of traffic people want to live in a peaceful environment with proper facility. As per the demand of people the high rise building are being constructed. For living purpose as well as for office purpose most of the people are searching for the high rise building with proper facility. Also due to the growing of population and due to the land scarcity people are unable to find the perfect place to settle so to provide the people choice the demand of high rise building is increases. Also for the management of the city the demand of high rise building is increases. There are many high rise building construction work is going on in india because of it more demand according to the people wish. Demand of high rise building is increases not only for the living but also for the business purpose.

As the high rise building are constructed rapidly and the demand of high rise building is also very high for the growing population due to the scarcity of land. For the construction of high rise building there is some requirement that should be fulfilled. Safety and health facility is the most requirement of the high rise building. Indian cities are witnessing immense demographic expansion due to migration from surrounding villages, leading to urban sprawl, housing demand, rise in cost of land. Many citizens all over India migrate to the cities for better jobs and education. Industries, trade and commerce activities and number of educational centres in cities attract floating population from all their surrounding villages and districts. This has expanded the cities in all directions and all aspects of development. With an urban sprawl of kilometres, these face the problems of congestion, pollution, everyday commuting to workplace, competition, deforestation etc. The development can be categorized in four categories considering different philosophy: High Rise with High Density; High Rise with Low Density; Low Rise with High Density; and Low Rise with Low Density. In India, a building greater than 75ft (23 m), generally 7 to 10 stories, is considered as high-rise. Also a building is considered to be high-rise when it extends higher than the maximum reach available to firefighters. According to the building code of India, a tall building is one with four floors or more or a high-rise building is one 15 meters or more in height. Most of the tall buildings in India are in the commercial capital Mumbai. More than 2500 high-rise buildings are already constructed. In addition more than thousand mid-rises exist already in the city. Mumbai is undergoing a massive construction boom, with thousands of tall buildings and about fifteen high-rise structures are under construction. Delhi and its surrounding regions are witnessing huge construction activities with 1500 already constructed high-rises.

The Law Maintenance; The Pre-Requisites

Most Indian statutes refer to tall buildings as ‘high rise building’. The development control regulations of some States distinguish a high-rise building in terms of its height. Some State by laws define a high rise building as being 35 meters or greater in height, which is divided at regular intervals into, levels able to be occupied. A high rise building is distinguished from all other manmade structures by the following general guidelines: Must be divided into multiple levels of at least 2 meters height; If it has fewer than 12 interval levels, then the highest undivided portion must not exceed 50% of the total height; Distinct divisions of levels such as stairways shall not be considered floors for the purposes of eligibility of this definition.

Where a high rise building is proposed to be built, its site must fall within the appropriate zoning area in accordance with the local development plan and zoning regulations provided by the planning authority building either cannot be built or prior approvals would have to be obtained from the local planning authorities for changing the existing land use. Planning authorities for some cities have zoned special areas for the construction of high rise buildings. If a high rise building is proposed in a residentially zoned area then prior approvals would have to be obtained from the local planning authorities.

Construction of high rise buildings involves a number of approvals and permissions from the Municipality or the Planning Authority (together hereinafter referred to as the “Appropriate Authority”), whichever is the relevant authority. The developer may first have to apply for bifurcation or amalgamation of the plot or conversion of land from the appropriate authorities. Thereafter, the developer has to apply for a license for construction of a building. The application has to be filed with the Appropriate Authority and this application must be accompanied by previously sanctioned drawings, key plan, site plan and the building plan. Once the license is issued, the developer has to obtain a commencement certificate from the Appropriate Authority. The limitation period for commencement of work once the license has been obtained is generally two years (this limitation may vary from one State to another).

Before commencement of construction, a No Objection Certificate has to be obtained from the following authorities: Water Supply & Sewerage Board, a local body responsible for the supply of potable water and treatment of sewage; Fire Services Department; Airport Authority of India; and Telecommunication Department (in case of high rise building above 7 floors).

Pre and post construction licenses must be obtained from the above listed authorities. These authorities work in close coordination with the Appropriate Authorities and assess the feasibility of constructing a high rise building and whether local infrastructure and amenities are capable of supporting the development on a long term basis. While preparing building plans for approvals from Appropriate Authorities the building should be provided with proper setbacks as per specifications provided in the local building by laws. Should there be any deviation from the specified setbacks, the building will be considered non compliant. Setbacks are minimum open spaces required to be maintained between the plot boundary and the building proposed to be constructed. They are meant to ensure light, ventilation and privacy not only to the development under consideration but also to the neighbouring buildings. In large buildings setbacks serve as circulation spaces and facilitate parking of vehicles. In the case of high rise buildings they are required not only for the movement of fire tenders around the building but also for preventing the fire from spreading to neighbouring buildings. In case of high rise buildings the setback required is directly proportional to the height of the building. The minimum required setback is 9 m and increases as the height of the building increases.

A building license fee has to be paid and a ground rent for stockpiling of building materials on public space has to be paid to the Appropriate Authority. The sanctioned plan and building construction license must be displayed at the construction site.

During construction, engineers appointed by the Planning Authorities will inspect the works to confirm whether the construction is in conformity with the approved building plans. The Planning Authorities are empowered to conduct any number of visits to the construction site to ensure that the construction activity is not interfering unduly with the immediate surroundings. Regular checks are also undertaken to inspect facilities offered to workmen including occupational safety and health facilities. The area executive engineer and assistant executive engineer usually inspect the construction on three occasions: first when the building reaches the plinth level, then when work reaches the lintel level and finally, after the construction is completed. At the final stage, an occupancy certificate will be issued only if it is found that the builder has not deviated from the sanctioned plan.

The Need and the Safety:

Mumbai continues to have the maximum number of tall buildings approved or under construction. Development of India One – the tallest in the country – has already begun in Maximum City. It spans 126 floors and stretches up to a height of 720 metres. Apart from this, Mumbai has more than 30 such super-tall buildings ranging between the heights of 150 metres to 450 metres either at the approval stage or already under construction. New Delhi, the capital of India, has around a dozen of such buildings coming up. They range between heights of 150-300 metres. Kolkata too is catching up with 9 such residential buildings extending to the height of 245 metres either approved or under construction. Ahmedabad too has about 13 tall buildings which are under construction and are ranging between 200 metres to 410 metres. Hyderabad and Bangalore too are witnessing some development in construction of tall buildings for residential-commercial purpose with 2 or 3 approved projects. All in all, this amounts to around 60 skyscrapers.

In 2015 Bengaluru’s elite look skywards for a way out of the city’s traffic congestion, 20 high-rise buildings, including 10 residential towers, have been given clearances to have helipads for commercial and personal use.

Developers see such edifices as a good way to attract potential buyers – high-rise buildings are a good gambit to differentiate their offerings from the rest of the pack. However, this coin has two sides high-rise development has its own share of demerits, too: According to experts, as cities gear up to cope with the increasing population, the tall building may well become the new normal, not by choice, but by default. Some common advantages High-Rise developments are More Natural Light, Ventilation and Fresh Air, Less Noise, Less Congestion, Feel of exclusive living to name a few.

Safety factor is a very important point. As skyscrapers take svelte new shapes, the safety aspect is the uppermost concern for buyers. As far as earthquakes are concerned, India is divided into five zones based on risk Most tall buildings that are under construction fall in zones 1 to 3 and are being designed to withstand quakes. Similarly, there are provisions to handle mass evacuations. This can take place from the ground as well as from the top floor, where most tall buildings have a helipad. Aesthetics and Sustainability are the issues of paramount importance when planning for any high rise construction. Experts feel that development of highrises need careful consideration on certain aspects at different stages since planning of the project until its completion so that it should be sustainable for occupants. aesthetic design is generally a primary requirement for an effective highrise building. However, the construction industry in India needs to focus more on safe highrises, as the need for construction of tall buildings in metros is increasing. He elaborated that construction of a highrise in India is taking care to prevent earthquake disasters through seismic-proof buildings. According to experts Most highrises are designed with fire-resistant material so that the chances of the whole building catching fire are lower, averred Vasudevan. Meanwhile for evacuation during an emergency, there are floors designed at various levels, where people can gather during calamities. Open spaces in the building, like staircases are designed to evacuate a larger number of people. At the same time, these high rise buildings are designed to withstand earthquakes as well. If a city falls in a potential earthquake zone of 3 on the Richter scale, tall buildings are designed to sustain a quake of level 5 or 6. High-rises are often located in premium neighbourhoods that affording a single family or walk up unit would be extremely expensive. Secondly, living in a high rise often gives you walking access to great restaurants, public transportation and possibly your place of employment.

List of Cities with High Rise Building in India:

India is the developed country where there are total population. In most of the cities of india the construction of high rise building is going rapidly with the township. . To fulfill the need of the people and also for the planning of the cities the construction of the high rise building is going rapidly. The most of the people are interested to stay in the high rise building where they can have a full security, safety and health. The cities of india where the high rise building are constructed are listed as following (1)Mumbai, (2)Delhi, (3)Kolkata, (4)Hyderabad, (5)Banglore, (6)Vijayawada, (7)Chennai, (8)Lucknow, (9)Gujarat.

Hand in Hand with Urbanization

A United Nations report called ‘World Urbanization Prospects’ says that in the coming years, India, China and Nigeria will witness maximum urban growth and that by 2050, India is projected to add 404 million urban dwellers. Population is increasing at a rapid pace. To tussle he growing space crunch in cities, we need to expand vertically. We need to create safe, secure and sustainable high-rises. Besides altering the city’s architectural landscape and skyline, skyscrapers make economic use of space and minimize urban sprawl. While designing super-tall towers, ample attention must be paid to water and waste management, energy usage and other related infrastructure. Architects and urban planners must take care to ensure that such structures do not put a strain on urban resources. In fact, they should be sustainable structures that use energy efficiently. There should be an emphasis on renewable energy, environment-friendly design and intelligent use of technology. As more and more smart cities get created, the number of skyscrapers is only going to go up.

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