rigid, core, braced

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Group 1

ABSTRACT

The high-rise building is generally defined as one that is taller than the maximum heightwhich people are willing to walk up; it thus requires mechanical vertical transportation. Thisincludes a rather limited range of building uses, primarily residential apartments, hotels, andoffice buildings, though occasionally including retail and educational facilities. A type that hasappeared recently is the mixed-use building, which contains varying amounts of residential,office, hotel, or commercial space.

The design and construction of skyscrapers involves creating safe, habitable spaces invery tall buildings. The buildings must support their weight, resist wind and earthquakes, andprotect occupants from fire. Yet they must also be conveniently accessible, even on the upperfloors, and provide utilities and a comfortable climate for the occupants. The problems posed in

skyscraper design are considered among the most complex encountered given the balancesrequired between economics, engineering, and construction management.

One common feature of skyscrapers is having a steel framework from which curtainwalls are suspended, rather than load-bearing walls of conventional construction. Mostskyscrapers have a steel frame that enables to build taller than load-bearing walls of reinforcedconcrete. Skyscrapers usually have particularly small surface area of what are conventionallythought of as walls, because the walls are not load-bearing and therefore most skyscrapers arecharacterized by large surface areas of windows made possible by the concept of steel frameand curtain walls. However, skyscrapers can have curtain walls that mimick conventional wallsand a small surface area of windows.

The concept of a skyscraper is a product of the industrialized age, made possible bycheap fossil fuel derived energy and industrially refined raw materials such as steel and

concrete. The construction of skyscrapers was enabled by steel frame construction thatsurpassed brick and mortar construction starting at the end of the 19th century and finallysurpassing it in the 20th century together with reinforced concrete construction as the price ofsteel decreased and labour costs increased.

The steel frames become inefficient and uneconomic for super tall buildings as usablefloor spaces are reduced for supporting column and due to more usage of steel.

KEYWORDS: High Rise, High Density Structure, Construction, Skyscraper, Types of StructuralConstruction, Rigid Frame, Core Structure, Braced Frame

TERMS AND DEFINITIONS

Braced frames are cantilevered vertical trusses resisting laterals loads primarily through theaxial stiffness of the frame members.

Dead loads arise from the weight of the individual construction elements and the finishingloads.


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A frame can be classified as non-sway if its response to in-plane horizontal forces is sufficientlystiff for it to be acceptably accurate to neglect any additional internal forces or moments arisingfrom horizontal displacements of its nodes"

High rise StructuresA high-rise is a tall building or structure

Buildings between 75 feet and 491 feet (23 m to 150 m) high are considered high -rises.Buildings taller than 492 feet (150 m) are classified as skyscrapers.The materials used for the structural system ofhigh-rise buildings are reinforced concrete andsteel. Most American style skyscrapers have a steel frame, while residential tower blocks areusually constructed out of concrete.High-rise structures have certain features. The structures are high &lead to higher verticalloads and higher lateral loads (mainly due to wind stress) in comparison with lower buildings.

Horizontal LoadsCalculation of lateral loads should be carefully scrutinized.It generally arises from unexpected deflections, wind and earthquake loads

Live loads are dependent on use depending on the number of stories, live loads can bereduced for load transfer and the dimensioning of vertical load-bearing elements.

Rigid Frame Structure are structure that is consist of columns and girders joined by momentresistant connections.

INTRODUCTIONA skyscraper is a tall, continuously habitable building of many storeys, usually designed

for office and commercial use. There is no official definition or height above which a buildingmay be classified as a skyscraper. One common feature of skyscrapers is having a steelframework from which curtain walls are suspended, rather than load-bearing walls ofconventional construction. Some early skyscrapers have a steel frame that enables the

construction of load-bearing walls taller than of those made of reinforced concrete. Modernskyscrapers' walls are not load-bearing, and most skyscrapers are characterized by largesurface areas of windows made possible by the concept of steel frame and curtain walls.However, skyscrapers can have curtain walls that mimic conventional walls and a small surfacearea of windows.

Skyscrapers since the 1960s use the tubular designs, innovated by Bangladeshi-American structural engineer Fazlur Rahman Khan. This engineering principle makes thebuildings structurally more efficient and stronger. It reduces the usage of material (economicallymuch more efficient), while simultaneously allows the buildings to reach greater heights. Itallows fewer interior columns, and so creates more usable floor space. It further enablesbuildings to take on various shapes. There are several variations of the tubular design; thesestructural systems are fundamental to tall building design today.Other pioneers include Hal

Iyengar, William LeMessurier, etc. Cities have experienced a huge surge in skyscraperconstruction.

Today, skyscrapers are an increasingly common sight where land is expensive, as in thecentres of big cities, because they provide such a high ratio of rentable floor space per unit areaof land. They are built not just for economy of space; like temples and palaces of the past,skyscrapers are considered symbols of a city's economic power. Not only do they define theskyline, they help to define the city's identity. In some cases, exceptionally tall skyscrapers havebeen built not out of necessity, but to help define the city's identity and presence or power as acity.


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HISTORYBuilding construction is an ancient human activity. It began with the purely functional

need for a controlled environment to moderate the effects of climate. Constructed shelters wereone means by which human beings were able to adapt themselves to a wide variety of climatesand become a global species.

Pre-19th CenturyUntil the 19th century, buildings of over six storeys were rare, as having great numbers

of stairs to climb was impractical for inhabitants, and water pressure was usually insufficient tosupply running water above 50 m (164 ft).The tallest building in ancient times was the 146 m (479 ft) Great Pyramid of Giza in ancientEgypt, built in the 26th century BCE. It was not surpassed in height for thousands of years, the14th century CE Lincoln Cathedral being conjectured by many to exceed it.[16] The latter in turnwas not surpassed until the 555 feet (169 m) Washington Monument in 1884. However, beinguninhabited, none of these structures actually comply with the modern definition of askyscraper.

High-rise apartments flourished in classical antiquity. Ancient Roman insulae there andin other imperial cities reached 10 and more storeys. Beginning with Augustus (r. 30 BCE-14

CE), several emperors attempted to establish limits of 2025 m for multi-storey buildings, butmet with only limited success. Lower floors were typically occupied by shops or wealthyfamilies, the upper rented to the lower classes. Surviving Oxyrhynchus Papyri indicate thatseven-storey buildings existed in provincial towns such as in 3rd century CE Hermopolis inRoman Egypt.

The skylines of many important medieval cities had large numbers of high-rise urbantowers, built by the wealthy for defense and status. The residential Towers of 12th centuryBologna numbered between 80 to 100 at a time, the tallest of which is the 97.2 m (319 ft) high

Asinelli Tower. A Florentine law of 1251 decreed that all urban buildings be immediatelyreduced to less than 26 m. Even medium-sized towns of the era are known to haveproliferations of towers, such as the 72 up to 51 m height in San Gimignano.

The medieval Egyptian city of Fustat housed many high-rise residential buildings, which

Al-Muqaddasi in the 10th century described as resembling minarets. Nasir Khusraw in the early11th century described some of them rising up to 14 storeys, with roof gardens on the top floorcomplete with ox-drawn water wheels for irrigating them. Cairo in the 16th century had high-riseapartment buildings where the two lower floors were for commercial and storage purposes andthe multiple storeys above them were rented out to tenants. An early example of a cityconsisting entirely of high-rise housing is the 16th-century city of Shibam in Yemen. Shibam wasmade up of over 500 tower houses, each one rising 5 to 11 storeys high, with each floor beingan apartment occupied by a single family. The city was built in this way in order to protect it fromBedouin attacks. Shibam still has the tallest mudbrick buildings in the world, with many of themover 30 m (98 ft) high.

An early modern example of high-rise housing was in 17th-century Edinburgh, Scotland,where a defensive city wall defined the boundaries of the city. Due to the restricted land area

available for development, the houses increased in height instead. Buildings of 11 storeys werecommon, and there are records of buildings as high as 14 storeys. Many of the stone-builtstructures can still be seen today in the old town of Edinburgh. The oldest iron framed buildingin the world, although only partially iron framed, is The Flaxmill (also locally known as the"Maltings"), in Shrewsbury, England. Built in 1797, it is seen as the "grandfather of skyscrapers,since its fireproof combination of cast iron columns and cast iron beams developed into themodern steel frame that made modern skyscrapers possible. In 2013 funding was confirmed toconvert the derelict building into offices.


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Early Skyscraper

In 1852 Elisha Otis introduced the safety elevator, allowing convenient and safepassenger movement to upper floors. Another crucial development was the use of a steel frameinstead of stone or brick, otherwise the walls on the lower floors on a tall building would be toothick to be practical. An early development in this area was Oriel Chambers in Liverpool.

Designed by local architect Peter Ellis in 1864, the building was the world's first iron-framed,glass curtain-walled office building. It was only 5 floors high. Further developments led to theworld's first skyscraper, the ten-storey Home Insurance Building in Chicago, built in 18841885.While its height is not considered very impressive today, it was at that time. The architect, MajorWilliam Le Baron Jenney, created a load-bearing structural frame. In this building, a steel framesupported the entire weight of the walls, instead of load-bearing walls carrying the weight of thebuilding. This development led to the "Chicago skeleton" form of construction. In addition to thesteel frame, the Home Insurance Building also utilized fireproofing, elevators, and electricalwiring, key elements in most skyscrapers today.

Burnham and Root's 1889 Rand McNally Building in Chicago, 1889, was the first all-steel framed skyscraper, while Louis Sullivan's Wainwright Building in St. Louis, Missouri, 1891,was the first steel-framed building with soaring vertical bands to emphasize the height of the

building and is therefore considered by some to be the first true skyscraper.Most early skyscrapers emerged in the land-strapped areas of Chicago, London, and New Yorktoward the end of the 19th century. A land boom in Melbourne, Australia between 18881891spurred the creation of a significant number of early skyscrapers, though none of these weresteel reinforced and few remain today. Height limits and fire restrictions were later introduced.London builders soon found building heights limited due to a complaint from Queen Victoria,rules that continued to exist with few exceptions until the 1950s. Concerns about aesthetics andfire safety had likewise hampered the development of skyscrapers across continental Europe forthe first half of the twentieth century (with the notable exceptions of the 1898 Witte Huis (WhiteHouse) in Rotterdam; the Royal Liver Building in Liverpool, completed in 1911 and 90 m (300 ft)high; and the 17-storey Kungstornen (Kings' Towers) in Stockholm, Sweden, which were built192425, the 15-storey Edificio Telefnica in Madrid, Spain, built in 1929; the 26-storey

Boerentoren in Antwerp, Belgium, built in 1932; and the 31-storey Torre Piacentini in Genoa,Italy, built in 1940). After an early competition between Chicago and New York City for theworld's tallest building, New York took the lead by 1895 with the completion of the AmericanSurety Building, leaving New York with the title of tallest building for many years. New York Citydevelopers competed among themselves, with successively taller buildings claiming the title of"world's tallest" in the 1920s and early 1930s, culminating with the completion of the ChryslerBuilding in 1930 and the Empire State Building in 1931, the world's tallest building for fortyyears. The first completed World Trade Center tower became the world's tallest building in1972. However, it was soon overtaken by the Sears Tower (now Willis Tower) in Chicago withintwo years. The Sears Tower stood as the world's tallest building for 24 years, from 1974 until1998, until it was edged out by Petronas Twin Towers in Kuala Lumpur, which held the title forsix years.


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Modern SkyscraperModern skyscrapers are built with steel or reinforced concrete frameworks and curtain

walls of glass or polished stone. They utilize mechanical equipment such as water pumps andelevators. From the 1930s onwards, skyscrapers began to appear around the world - also inLatin America (such as So Paulo, Rio de Janeiro, Buenos Aires, Santiago, Caracas, Bogot,Mexico City) and in Asia (Tokyo, Shanghai, Hong Kong, Manila, Singapore, Mumbai, Seoul,

Kuala Lumpur, Taipei, Bangkok).Immediately after World War II, the Soviet Union planned eight massive skyscrapers

dubbed "Stalin Towers" for Moscow; seven of these were eventually built. The rest of Europealso slowly began to permit skyscrapers, starting with Madrid, during the 1950s. Finally,skyscrapers also began to be constructed in cities of Africa, the Middle East and Oceania(mainly Australia) from the late 1950s. After the Great Depression skyscrapers construction wasabandoned for over thirty years.

German architect Ludwig Mies van der Rohe became one of the world's most renownedarchitects in the second half of the 20th century. He conceived of the glass faade skyscraperand designed the Seagram Building in 1958, a skyscraper that is often regarded as the pinnacleof the modernist high-rise architecture.

In the early 1960s structural engineer Fazlur Khan realized that the rigid steel frame

structure that had dominated tall building design and construction so long was not the onlysystem fitting for tall buildings, marking the beginning of a new era of skyscraper revolution interms of multiple structural systems. His central innovation in skyscraper design andconstruction was the idea of the "tube" structural system, including the "framed tube", "trussedtube", and "bundled tube". These systems allowed far greater economic efficiency, and alsoallowed efficient skyscrapers to take on various shapes, no longer needing to be box-shaped.Over the next fifteen years, many towers were built by Khan and the "Second Chicago School",including the massive 442 m (1,450 ft) Willis Tower. The tubular systems are fundamental totall building design. Since 2000, cities such as Chicago, Shanghai, Dubai, and New York haveexperienced a huge surge in skyscraper construction, thanks to the new tubular design.Chicago, Hong Kong, and New York City, otherwise known as "the big three," are recognized inarchitectural circles as having especially compelling skylines. A landmark skyscraper can inspire

a boom of new high-rise projects in its city, as Taipei 101 has done in Taipei since its opening in2004. In 2010, The Bank of America Tower at One Bryant Park became the world's firstcommercial LEED Platinum skyscraper.


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TALL BUILDING STRUCTURES

As building height increases, the three basic systems of lateral

force resistance--- shear wall, braced frame, and rigid frame

may be employed in unique ways. The following tall building

configurations are presented in order of suitability for structures

of increasing height. The adjacent diagrams illustrate

schematically in both plan and section each of the configurations

described.

CONVENTIONAL STRUCTURAL CONFIGURATIONS

The conventional arrangements of stabilizing elements used in

low-rise buildings may be extended for use in buildings up to 20

to 25 stories in height. The same considerations that apply to

low-rise buildings apply to taller buildings as well: stabilizing

elements should be arranged so as to resist lateral forces along

all major axes of the building. These elements should be

arranged in a balanced manner either within the building or at

the perimeter. And such elements must be integrated with the

building plan or elevation.

Shear walls and braced frames are the stabilizing elements

most commonly used in buildings of this height, due to their

structural efficiency. They may be used either separately or in

combination. The use of rigid frame systems are as the sole

means of achieving lateral stability may be feasible in buildings

up to 15-20 stories in height in areas of low seismic activity.However, even where feasible, rigid frame structures may be a

less attractive option due to the greater difficulty of their

fabrication and the increased size of the beams and columns

required. More commonly in buildings of this height, rigid frame

components are used in combination with either shear walls or

braced frames to enhance the lateral resistance of the structure

as a whole.

RIGID FRAME STRUCTURE

A rigid frame structure is a structure made up of linear element, typically beams andcolumns that are connected to one another at their ends with joints that do not allow any relativerotations to occur between the ends of the attached members, although the joints themselvesmay rotate as a unit. Members are essentially continuous through the joints. As with continuousbeams, rigid-frame structures are statically indeterminate.

Many rigid-frame structures resemble simpler post-and-beam systems in appearance,but are radically different in structural behavior, owing to the joint rigidity, which can be sufficientto enable a framed structure to carry significant lateral loads, something a simpler post-and-beam system cannot do without additional bracing elements. Variants of rigid frame structures


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have been used for a long time. A common table, forexample, typically derives its stability from the rigid jointsthat are used to connect the legs to the tabletop. Thetraditional knee-braced timber structure can also bethought of as a type of rigid-frame structure. Still, the rigidframe as a widely used structural device in major buildings

is a relatively recent phenomenon. The development of thesteel rigid frame in cities such as Chicago during the latterpart of the 19th and early part of the 20th centuries is amajor event in the history of structures. The relatedmovement of separating and differentiating enclosuresurfaces from supporting structural skeleton, madepossible by the introduction of the rigid frame, also marks amajor turning point in the history of architecture. Thismovement was a marked departure from traditionalbuilding practices that made extensive use of dual-functioning elements, such as exterior load-bearing wall,which served simultaneously as both structural and

enclosure.

Summary of the Rigid Frame Definition

Consist of columns and girders joined by momentresistant connections.

Lateral stiffness of a rigid frame bent depends onthe bending stiffness of the columns, girders, andconnection in the plane of the bents.

Ideally suited for reinforced concrete buildingsbecause of the inherent rigidity of reinforcedconcrete joints.

Also used for steel frame buildings, but moment-

resistant connections in steel tend to be costly. While rigid frame of a typical scale that serve

alone to resist lateral loading have an economicheight limit of about 25 stories, smaller scale rigidframes in the form of perimeter tube, or typicallyrigid frames in combination with shear walls orbraced bents, can be economic up top muchgreater heights.

Advantages:

May be place in or around the core, on the exterior, or throughout the interior of thebuilding with minimal constraint on the planning module.

The frame may be architecturally exposed to express the grid-like nature of thestructure.

The spacing of the columns in a moment resisting frame can match that required forgravity framing.

Disadvantages:

rigid frames were suitable only at sites where unyielding foundations could be ensured,for uneven settlement produced a "bad effect" on their strength;


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placing of steel reinforcement in the concrete required considerable skill;

the sequence of concrete placement and removal of formwork was sometimes morecomplicated; and

Design of rigid frame bridges was somewhat more complex because such structureswere "statically indeterminate," and analysis was not as straightforward as in the case ofstatically determinate, simply supported spans. Only suitable for building up to 2030

stories only; member proportions and materials cost become unreasonable for buildinghigher than that.

Example

The Osaka World Trade Center Building comprises not only the main tower (with animpressive 76m x 35m footprint) but a low rise block and covered 3000 sq.m atrium as well. Theproject is park of the Technopark Osako development which comprises almost 800 hectaresincluding three artificial islands in the bay.

The tower houses public space, an auditorium, business support centres and officespace (7th thru 44th floors). The upper floors house a World Trade Center Museum,restaurants, Cosmo Hall, and other functional components. It is within this building that the"highest" marriages in Japan often take place.

The building is capped by the distinctive inverted pyramid which ofers 360-degree viewsof the city from the "Top of the Bay".


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points lower down) that engage the perimeters structural elements in the resistance to lateralloads, thus improving the performance of the building as a whole. These elements may becomeaesthetically expressed on the building faade or may be preferred locations for mechanicalfloors. Columns at the perimeter of the building may also increase in size with these systems.These core interactive structures are suitable for buildings up to approximately 60 stories inheight.

Outrigger serve to reduce the overturning moment in the core that would otherwise actas a pure cantilever, and to transfer the reduced moment to columns outside the core by theway of tension-compression coupled, which take advantage of the increase moment armbetween these columns. It also serves to reduce the critical connection where the mast isstepped to the keel beam.

In high-rise building this same benefit is realized by a reduction of the base core over-turning moments and the associated reduction in the potential core uplift forces.

In the foundations system, this core and outrigger system can lead to the need for thefollowing:

The addition of expensive and labor-intensive rock anchors to an otherwise simplefoundation alternative such as spread footing.

Greatly enlarged mat dimensions and depth solely to resist overturning forces.

Time-consuming and costly rock sockets for caisson systems along with the need to developreinforcement throughout the complete caisson depth.

Expensive and intensive field work connection at the interface between core and thefoundation. This connection can become particularly troublesome when one considers thedifference in construction tolerances between foundations and core structure.

The elimination from consideration of foundation systems which might have beenconsiderably less expensive, such as pile, solely for their inability to resist significant uplift.

Advantages:

The outrigger systems may be formed in any combination of steel, concrete, orcomposite construction.

Core overturning moments and their associated induced deformation can be reducedthrough the reverse moment applied to the core at each outrigger intersection. Thismoment is created by the force couple at the exterior columns to which the outriggerconnect. It can potentially increase the effective depth of the structural system from thecore only to almost the complete building.

Significant reduction and possibly the complete elimination of uplift and net tensionforces throughout the column and the foundation systems.

The exterior column spacing is not driven by structural considerations and can easilymesh with aesthetic and functional considerations.

Exterior framing can consist of simple beam and column framing without the need forrigid-frame-type connections, resulting in economies.

For rectangular buildings, outriggers can engage the middle columns on the long faces

of the building under the application of wind loads in the more critical direction. In core-alone and tubular systems, these columns which carry significant gravity load are eithernot incorporated or underutilized. In some cases, outrigger systems can efficientlyincorporate almost every gravity column into lateral load resisting system, leading tosignificant economies.

Disadvantages

The most significant drawback with use of outrigger systems is their potentialinterference with occupiable and rentable space.


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This obstacle can be minimized or in some cases eliminate by incorporation of any of thefollowing approaches:

-Locating outrigger in mechanical and interstitial levels -Locating outriggers in the natural sloping lines of the building profile -Incorporating multilevel single diagonal outriggers to minimize the members

interference on any single level.

-Skewing and offsetting outriggers in order to mesh with the functional layout ofthe floor space.

Another potential drawback is the impact the outrigger installation can have on theerection process. As a typical building erection proceeds, the repetitive nature of thestructural framing and the reduction in member sizes generally result in a learning curvewhich can speed the process along.

The incorporation of a outrigger at intermediate or upper levels can, if not approachedproperly, have a negative impact on the erection process. Several steps can be taken tominimize this possibility. Provide clear and concise erection guidelines in the contractdocuments so that the erector can anticipate the constraint and limitation that the installation willimpose. If possible, avoid outriggers locations or design constraints that will requirebacktracking in the construction process to install or connect the outrigger. The incorporation

of intermediate outriggers in concrete construction or large variation in dead-load columnstresses between the core and the exterior can in some cases result in the need to backtrack.Such a need can be minimized if issues such as creep and differential shortening are carefullystudied during the design process to minimize their impact. Avoid adding additional outriggerlevels for borderline force or deflection control.

Example

Citibank Plaza is a modern office complex that comprises two towers and a retailpodium. It is located at 3 Garden Road, Central, Hong Kong. Citibank Plaza is a modern glassand steel office complex in Hong Kong that comprises Citibank Tower, ICBC Tower, a 3 levelbasement garage capable of accommodating 558 vehicles, as well as a retail podium. With agross floor area of almost 1,600,000 sq ft (150,000 m2)., Citibank Plaza is one of the biggest


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office complexes in Hong Kong, capable of serving a working population of over 10,000. At 205metres tall, Citibank Tower reaches up to the 50th floor. The highest floor on ICBC Tower is the40th. Completed in 1992, it was one of the first office buildings in Hong Kong to incorporateintelligent building and environmentally friendly features.

Citibank Plaza is considered by many to be one of the Central Districts iconic structures.Besides its two characteristic curved reflective facades, the complex contains many distinct

architectural features, such as the flexibility to join 26 floors of both towers to provide anenlarged floor plate of up to 34,000 sq ft (3,200 m2). Two ten-storey tall frameless glass panelsprovide the main lobby with natural lighting and allow visitors to look thorough the building. Inrecognition of excellence in the area of architectural design, Citibank Plaza was presented withthe Hong Kong Institute of Architects highest award in 1994, the Silver Medal.

TUBE STRUCTURES

Many of the worlds tallest buildings are designedas tube structures. In this system, stabilizing elements arelocated at the perimeter of the structure, leaving the layout

of the interior of the building unrestricted by considerationsof lateral stability. Either braced frame or rigid frameelements, constructed from either steel or concrete, maybe used. Simple tube structures and their variations aregenerally suitable for buildings approximately 55 stories orgreater in height.

The use of rigid frame tubes may affect the sizeand spacing of framing elements at the perimeter of thebuilding. Beams may need to be deeper and columns mayneed to be larger and more closely spaced than wouldotherwise be required. When building in steel, the welded

joints required in this system may be more costly to

construct, although construction systems have beendeveloped that allow the off-site fabrication of these joints,minimizing this disadvantage. And as with core structures,the performance of rigid frame tubes may be enhancedwith hat trusses or belt trusses integrated within theperimeter structure.

Braced frame tubes are highly structurally efficient lateral load resisting configurations.When built in steel, these structures rely on more easily constructed hinged connections. Thediagonal braces that are an integral part of this system often have a significant impact on theappearance of the building faade.

Variations on the tube structure and other tall building configurations are also possible.Tube in tube structures allow perimeter tubes to interact with rigid cores. Bundled tube

structures allow greater variation in building massing. Space truss structures are similar tobraced tubes, with the addition of large scale diagonals that pass through the buildings interior.Diagrid structures rely on latticed frameworks that carry both vertical and lateral loads, with fewor no vertical columns.

Summary:

Braced frames are cantilevered vertical trusses resisting laterals loads primarily throughthe axial stiffness of the frame members.


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The effectiveness of the system, as characterized by a high ratio of stiffness to materialquantity, is recognized for multistory building in the low to mid height range.

Generally regarded as an exclusively steel system because the diagonal are inevitablysubjected to tension for or to the other directions of lateral loading.

Able to produce a laterally very stiff structure for a minimum of additional material,makes it an economical structural form for any height of buildings, up to the very tallest.

Advantages Girders only participate minimally in the lateral bracing action-Floor framing design is

independent of its level in the structure

Can be repetitive up the height of the building with obvious economy in design andfabrication.

Disadvantages

Obstruct the internal planning and the locations of the windows and doors; for thisreason, braced bent are usually incorporated internally along wall and partition lines,especially around elevator, stair, and service shaft.

Diagonal connections are expensive to fabricate and erect.

Example

ACT TOWERHamamatsu City, Japan


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Act Tower (?) is a skyscraper in Hamamatsu, Shizuoka Prefecture, Japan. It

is 213 metres (699 ft) tall, and has 45 floors, making it the tallest building in Hamamatsu, andthe tallest building in Japan outside of the Tokyo, Osaka, and Nagoya metropolitanareas.[citation needed] It was constructed in 1994, and houses the Okura City Hotel in its top 17floors, as well as observation deck on its top floor. The building was designed to resemble aharmonica, in line with Hamamatsu's notable music culture.


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OBJECTIVETo provide definitions that makes it possible to point out the essential characteristics of a framedstructure. Attention is given to joint behaviour and to the problem of the choice of structuralmodel depending on the loads acting on the structure.

CONCLUSION

Selection of frame Structures of the high rise building is due to the versatility andadvantages over the normal traditional load bearing structures. Actually, the performance ofload bearing structures is usually dependent on the mass of the structures. To fulfill thisrequirement of load bearing structures, there is the need of increase in volume of the structuralelements leads toward the construction of thick wall. Due to such type of construction, labor andconstruction cost increases, in construction of thick wall there will be the need of great attention,which will further reduce the speed of construction.

If we make the contrast of load bearing structure with the framed structures appear to bemore flexible, economical and can carry the heavy loads. Frame structures can be rehabilitatedat any time. Different services can be provided in frame structures. Thus frame structures areflexible in use.

rigid, core, braced

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