“HIGH RISE STRUCTURE”

SUBMITED BY :NIKITA LEKARIYAUTKARSHA POHANEPRANALI SATAWAKSHAY JAWALEKAR

B.ARCH 6TH SEMESTER

CONTENTS :

1. INTRODUCTION2. DEMANDS FOR HIGH RISE BUILDING3. MATERIAL4. TYPES OF SYSTEMS5. CONSTRUCTIONAL DETAILS6. PRECAUTIONS7. ADVANTAGES AND DISADVANTAGES8. LIMITATIONS

WHATS IS HIGH RISE STRUCTURE ?

There are different definition for high rise construction. -A high-rise building is one with four floors or more, or one 15 meters or more in height.

-Buildings between 75 feet and 491 feet (23 m to 150 m) high are considered high-rise.

-Buildings taller than 492 feet (150 m) are classified as skyscrapers.

Demands for high rise building

- Scarcity of land in urban area - increasing demands for residential and business space - economical growth - technological advancement - innovation in structural system - desire for aesthetic in urban setting - concept of city skyline - cultural significance and prestige - human aspiration to build higher

Material

Cast iron

Steel

R.C.C.Glass

Cast iron :- Cast Iron use has been overtaken by Steel. Cast Iron has little strength in tension but is very

strong in compression. It can still be found in some older High Rise buildings, usually to provide structural beams and columns.

Glass :- Float glass with double glass is used in tall buildings . Tempered glass is used in tall buildings instead of plain glass, as that would shatter at such height.

TYPES OF MATERIAL

Aluminium

30 St Mary's Axe, London

PVC

Density : 2000Kg/m3

Thickness : 220mm

Weight/Square meter : 440 Kg/m2

Density : 2.51 g/c3

Thickness : 12mm

(Taking into account, a double glazed unit 6mm outer glass - 12mm air gap - 6mm inner glass)

Weight/Square meter : 30kg/m2

So, considering a typical high rise building - 50 stories high with 40,000m2 glass area

Estimated weight reduction : 16,400 Tons

GLASS BRICK WALL

GLASS

Ease in installation

When it comes to installation, following are the advantages of a glass façade over a concrete one:

•Quicker fabrication & installation of glass façade

•In a single day of installation, a glass façade can cover 150 m2 in comparison with brick wall 70 m2.

•Dry construction while using glass, which implies a cleaner project site.

• Glass is 8 times lighter than a Brick wall facade!

• REINFORCED GLASS is a block which can withstand explosions, even (to some extent) nuclear explosions.

• It is created by combining 7 Glass with 2 Advanced Alloy. • Reinforced Glass is used in the creation of Irradiant Glass

Panes for Advanced Sola Panels as well as in the creation of the Quantum Helmet.

Structural glazing for high rise building:•Aesthetics•Signature designs•Flexibility•Robustness Glass has a multitude of benefits :Visual appeal•Lightness•Installation•Customization

Steel :- • Carbon is added and this acts as a hardener.

• Different mixes of steel will possess different characteristics from varying hardness and malleability to Corrosion resistance and weight.

• Its melting point is high at 1300C but it suffers from 3 key failings under fire conditions.

• Loss of strength …. at 600C a steel beam may lose two thirds of its strength.

• It is a good thermal conductor …. Meaning it can transfer its heat to involve other materials not directly exposed to fire.

• It has a high thermal expansion….. at 500C a 10 Steel beam can expand 60mm, if this beam was a structural

element within a building it may cause collapse.

• 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.

• Aluminium is a relatively soft and light metal with a melting point of 660C.

• Its lightness means it has uses in the construction industry for non-structural items, such as door and window frames and external cladding.

• Aluminium’s greatest weaknesses is the low temperature at which its structural stability is affected which can be as low as 100-250c, and its high thermal expansion (over twice that of steel).

• where aluminium is used as a framing material 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.

• Aluminium as an external cladding can melt if exposed to fire and the falling molten aluminium possess additional hazards.

ALUMINIUM

Bank Of Hong Kong

P.V.C. (POLY VINYL CHLORIDE) -

•Unplasticised polyvinyl chloride is a lightweight is widely used as a framing and cladding material.

•t is also extensively used in plumbing as pipe material for waste and rainwater.

•It is very durable but weak and like most plastics has a low decomposition temperature (of around 220℃) and will liberate a large amount of acrid smoke.

•It has been extensively used in the refurbishment of many UK tower blocks from the 60’s and 70’s to provide double glazed windows and balcony doors.

• Upvc does not burn freely and has class 1 fire rating but if exposed to fire it will fail very early at an incident and, importantly to fire crews when used as a framing material (especially external windows) this can lead to floor to floor compromise.

REINFORCED CONCRETE

• A relatively modern addition to concrete has been fiber reinforcement. This can be as a replacement to in addition to conventional steel reinforcement.

• Most large scale concrete construction in the world is now carried out using this technique and the liquid concrete can be pumped or craned up buildings as construction progresses.

• The concrete mixes used in this technique are formulated to an exacting standard and the rebar is usually coated to protect it from corrosion.

• 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 contain quartz which will start to crack and disintegrate at 600C.

• It is the type and quantity of aggregate in the concrete mix that will define its inherent fire resistance properties.

• Gravity loads– Dead loads– Live loads– Snow loads

• Lateral loads– Wind loads– Seismic loads

• Special load cases– Impact loads– Blast loads

Seismic Loads

LOADS ON HIGH RISE BUILDING

Characteristics Of Wind

• Variation of wind velocity with height.• Wind turbulence.• Statistical Probability.• Vortex shedding phenomenon.• Dynamic nature of wind-structure interaction.

Types of wind

• Winds that are of interest in the design of buildings can be classified into 3 major types - prevailing winds (trade winds) -seasonal winds -local winds

WINDS Causes of Wind-• Variation of Wind Velocity with Height-Near the earth’s surface, the motion is opposed, and the wind speed reduced, by the surface friction. •At the surface, the wind speed reduces to zero and then begins to increase with height•Gradient Height 300 m for flat ground& 550 m for very rough terrain.

• How wind force governing for tall structure with increase height of building?•Construction cost per unit area decrease •Increasing lightness in weight per unit area •More danger against high velocity of wind force at high level.

•Wind load are always important for tall buildings ,which form a vertical cantilever resisting the horizontal wind pressure on one side and horizontal suction on the other side.

•The building behaves like a horizontal cantilevered beam resisting a vertical load; for a high rise building the span of the cantilever is much greater than any horizontal span in a building.

Variation of wind velocity with height

-The viscosity of air reduces its velocity adjacent to the earth’s surface to almost zero.

Wind behavior

TYPES OF SYSTEM

1. Shear wall System2. Braced system3. Hybrid System 4. Moment Resisting System5. Trussed Tube6. Bundled Frame Tube7. Frame Tube

STEEL STRUCTURAL SYSTEMS AND THE NO. OF STOREYS

SHEAR WALL SYSTEM

• A type of rigid frame construction.• The shear wall is in steel or concrete to provide greater

lateral rigidity. • It is a wall where the entire material of the wall is

employed in the resistance of both horizontal and vertical loads.

• Is composed of braced panels (or shear panels) to counter the effects of lateral load acting on a structure.

• Wind & earthquake loads are the most common among the loads.

• For skyscrapers, as the size of the structure increases, so does the size of the supporting wall.

• Shear walls tend to be used only in conjunction with other support systems.

BRACED SYSTEM

•Frame are cantilevered vertical trusses resisting laterals loads primarily through the axial stiffness of the frame members.

•The effectiveness of the system, as characterized by a high ratio of stiffness to material quantity, is recognized for multi- storey building in the low to mid height range.

•Generally regarded as an exclusively steel system because the diagonal are inevitably subjected 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.

KOBE COMMERCEINDUSTRY AND TRADE CENTER,

KOBE,JAPAN

Architect : Nikken Sekkei ltd.Structural engineer : Nikken Sekkei ltd.Year of completion : 1968Height : 110.06mNumber of stories : 26Stories below ground: 2Frame material : steelFoundation condition : gravel and diluvial clay strataFooting type: raftStory ht. : 3.84mBeam span : 9.45mBeam depth : 600mmBeam spacing : 3mMaterial : steel grade 400mpa;concrete encased structural steel 1st floor below

Slab: 160mm concrete on metal deck

Columns:At ground floor: 700mm x 700mmSpacing: 3mMaterial: steel grade 490 mpaCore: structural steel with prestressing bar diagonal bracing

Kobe CommerceKobe , Japan

KOBE COMMERCE

• This building characterized by its tube in tube structure.

• Also consist of perimeter wall frames with 3m spans and internal braced frames using prestressing steel bars for diagonal bracings.

• For purpose of efficiently increasing the earthquake resisting capacity of a building ,it is preferable to design its structure in a bending failure mode so as to disperse the yielding of frames during earthquake.

• Tube in tube structure in used for this.

• Braces has a wide elastic range and thus can resist the maximum seismic forces within elastic region.

HYBRID SYSTEM

• Combination of two or more of basic structural forms either by direct combination or by adopting different forms in different parts of the structure.

HIGH STRENGTH CONRETE

STIFFNESS

DAMPING OF

CONCRETE ELEMENTS

LIGHTNESS CONSTRUCT

ABILITY OF STEEL FRAME

• Its lack of torsional stiffness requires that additional measures be taken, which resulted in one bay vertical exterior bracing and a number of level of perimeter vierendeel “bandages”

MOMENT RESISTING SYSTEM

• Definition and basic behavior of moment resistingFrames

• Beam-to-column connections: before and afterNorthridge

• Panel-zone behavior

• AISC seismic provisions for moment resistingFrames: special, intermediate and ordinary

TRUSSED TUBE

• Interconnect all exterior columns to form a rigid box, which can resist lateral shears by axial in its members rather than through flexure.

• Introducing a minimum number of diagonals on each façade and making the diagonal intersect at the same point at the corner column.

• The system is tubular in that the fascia diagonals not only form a truss in the plane, but also interact with the trusses on the perpendicular faces to affect the tubular behavior.

• Relatively broad column spacing can resulted large clear spaces for windows, a particular characteristic of steel buildings.

• The façade diagonalization serves to equalize the gravity loads of the exterior columns that give a significant impact on the exterior architecture.

John Hancock Center

• The concept allows for wider column spacing in the tubular walls.

• The spacing which make it possible to place interior frame lines without seriously compromising interior space planning.

• The ability to modulate the cells vertically can create a powerful vocabulary for a variety of dynamic shapes.

BUNDLED FRAME TUBE

Willis tower, Chicago.

FRAMED TUBE

• The lateral resistant of the framed-tube structures is provided by very stiff moment-resistant frames.

• The basic inefficiency of the frame system for reinforced concrete buildings of more than 15 stories resulted in member proportions of prohibitive size and structural material cost premium.

• The frames consist of 6-12 ft (2-4m) between centers, joined by deep spandrel girders.

• Gravity loading is shared between the tube and interior column or walls.

• When lateral loading acts, the perimeter frame aligned in the direction of loading acts as the “webs” of the massive tube of the cantilever, and those normal to the direction of the loading act as the “flanges”.

• The tube form was developed originally for building of rectangular plan.Dewitt Chestnut

Raft foundation: It is known for its load distributing capability. • With the usage of this type of foundation the enormous load of the

building gets distributed & helps the building stay upright and sturdy.

• Loads are transferred by raft into the ground. Pile foundation: used for high rise construction.• Load Of building is distributed to the ground with the help Of piles. Transfer the loads into the ground with an Adequate factor of

safety. Combined raft-pile: is the hybrid of 2 foundation. • It Consists of both the pile and raft foundation. • Useful in marshy sandy soil that has low bearing capacity.

FOUNDATION TYPES

DESIGN CONSIDERATIONS

Location and Height

Function : • Function is one of the significant architectural parameters of tall buildings. As seen

in (Figure 4), mixed-use and office buildings are the two main types of function in this type of building.

• Those are both around 77% of the total number of the tall buildings.

Base Plan : • One of the important architectural factors representing the geometry and form of a

tall building is its base plan shape. • This parameter is divided into six basic and simple shapes. These are rectangle,

ellipse and circle, curvilinear, triangle, polygon and parallelogram shapes. • With these classifications, small variations in the base plan are not considered as a

separate group.

Form (based on aerodynamic and geometric characteristics :• For form classification, different types of the aerodynamic (and geometric)

modifications used in tall buildings are considered..

ARCHITECTURAL CONSIDERATIONS

• Unprecedented heights and forces because of increased wind speeds and thus forces through climate change now require designers to consider architectural and structural strategies that will improve the efficiency of the design process and of the building itself.

• The strategy of aerodynamic (geometric) modification is basically considered as a precautionary and passive architectural concept to reduce the impact of wind.

• The aerodynamic modifications can be divided into two main categories: macro and micro.

• Macro modifications, such as tapering, setback and twisting, have basic effect on the main geometry of the building whereas, micro modifications, such as corner modifications, cannot affect the base form and shape of the building.

Structural Material :• Selecting the structural material depends on such parameters as the function,

structural system, availability of material, and constructability. • Using composite materials offers the advantages of both steel and concrete. • Thus it is not surprising to find out that around 44% of all tall buildings are built

with composite materials and also to see that only %15 of the buildings used steel

Diagrid system

• Diagrid system can be considered as a braced tube system without vertical and horizontal structural elements.

• But, the aesthetic potential of the diagonal elements was not appreciated since they were designed and constructed to obstruct the outdoor viewing.

• Thus, diagonals were generally embedded within the building cores, which were usually located in the interior of the building to be hidden from the outside view.

• This system is recently used as a new aesthetic architectural-structural concept for tall buildings .

• One of the visible differences between conventional exterior braced frame system and current diagrid structures is that for diagrid structures almost all the conventional vertical columns are eliminated because the diagonal members in diagrid systems can continuously carry gravity as well as lateral loads due to their triangulated configuration in the uniform manner.

• This system in comparison with conventional framed tube system is much more effective in minimizing shear deformation because the diagrid system can carry shear by axial action of the diagonal members

COR Building, Miami

O-14 Building, Dubai

Advantages: • Accommodates large number of families and business

houses.• They reduce the distance to be travelled by occupants

saving their time.• Permit more open space around the building.• Provide more sunlight and pure air.• Vertical expansion results in curtailment of cost of various

services such as water supply electrification.• Saves land which can be used further.• Pressure coefficients should need little adjustment for

different upwind terrain types .• Existing meteorological data on wind gusts is used directly.

ADVANTAGES AND DISADVANTAGES

Disadvantages: • Construction cost increases.• Difficult for children and old people to go up when

elevators fails.• Enjoying the charm of private garden cannot be

obtained.• The approach is not suitable for very large

structures, or for those with significant dynamic response.

• The response characteristics of the gust anemometers and the natural variability of the peak gusts tend to be incorporated into the wind load estimates.