TALL STRUCTURES SEMINAR REPORT
[post_ad]
INTRODUCTION
The tall buildings has fascinated humans from the beginning of civilization as evidenced by the pyramids of Gaza,Egypt,Mayan temples of Tikal, Guatemala & Qutab Minar of Delhi,India.The motivation behind their construction was primarily for creating monumental rather than human habitats. By contrast, contemporary tall buildings are primarily a response to the demand by commercial activities, often developed for corporate organizations as prestige symbols in city centers. The feasibility of tall building has always depended upon the available materials & the development of the vertical transportation necessary for moving people up & down the buildings During last 120 years, three major types of structures have been employed in tall buildings. The first type was used in the cast-iron buildings of the 1850s to 1910,in which the gravity load was carried mostly by the exterior walls
POINTS TO BE CONSIDERED
It consists of a service core located at each corner of the building interconnected by a super diagonal in fill bracing. The service core at each corner acts as a giant-column carrying most of the gravity load & overturning moments. The adoration that sky scrapers command lies in their apparent freedom from gravity loads, they do not just stand tall, they do so effortlessly.
The eccentricity between the super diagonals & exterior columns is a deliberate designs strategy to enhance the ductility of the lateral bracing systems.
The ductile response of the links helps in dissipating seismic energy, thus assuring the gravity carrying capacity of the building during & after a large earthquake.
A building in seismically active regions must be able to resist realistic earthquake forces without losing its vertical load carrying capacity.
PRESTRESSED CONCRETE
The term “ prestressed concrete “ is applied to those reinforced concrete members in which concrete is subjected to compressive stresses, before external loads are applied, by inducing tensile stresses in the reinforcement to counteract tensile stresses in the concrete caused by external loads.
APPLICATIONS:
Prestressed concrete can be applied to almost all concrete constructions where ordinary reinforced concrete is used.
But due to high cost of prestressing & better quality of materials used, its use is made under special conditions, particularly for precast members.
In addition to structural precast members,eg. Joints,beams,slabs,columns,girders,etc,prestressed concrete is used for the framed multistoried block, such as offices,flats,hotels,hospitals,etc.
Also various types of industrial structures like silos,hangers,roof trusses, water tank,piles,pipes,factories,steel plants,etc. Can be built in prestressed concrete.
ADVANTAGES
The size or dimension of structural members are reduced. It permits the use of large spans greater than 30m, with shallow members, even when heavy loads are encountered. There is considerable saving in cost of supporting members & foundations. Because of controlled concrete & high tension steel being used & nullifying the effect of dead loads, smaller deflections are caused.
DISADVANTAGES
The unit cost of high strength materials being used is higher. Extra initial cost due to the use of prestressing equipment & its installation. Extra labour cost for prestressing.
Prestressing is uneconomical for short spans & light loads
The tall buildings has fascinated humans from the beginning of civilization as evidenced by the pyramids of Gaza,Egypt,Mayan temples of Tikal, Guatemala & Qutab Minar of Delhi,India.The motivation behind their construction was primarily for creating monumental rather than human habitats. By contrast, contemporary tall buildings are primarily a response to the demand by commercial activities, often developed for corporate organizations as prestige symbols in city centers. The feasibility of tall building has always depended upon the available materials & the development of the vertical transportation necessary for moving people up & down the buildings During last 120 years, three major types of structures have been employed in tall buildings. The first type was used in the cast-iron buildings of the 1850s to 1910,in which the gravity load was carried mostly by the exterior walls
POINTS TO BE CONSIDERED
It consists of a service core located at each corner of the building interconnected by a super diagonal in fill bracing. The service core at each corner acts as a giant-column carrying most of the gravity load & overturning moments. The adoration that sky scrapers command lies in their apparent freedom from gravity loads, they do not just stand tall, they do so effortlessly.
The eccentricity between the super diagonals & exterior columns is a deliberate designs strategy to enhance the ductility of the lateral bracing systems.
The ductile response of the links helps in dissipating seismic energy, thus assuring the gravity carrying capacity of the building during & after a large earthquake.
A building in seismically active regions must be able to resist realistic earthquake forces without losing its vertical load carrying capacity.
PRESTRESSED CONCRETE
The term “ prestressed concrete “ is applied to those reinforced concrete members in which concrete is subjected to compressive stresses, before external loads are applied, by inducing tensile stresses in the reinforcement to counteract tensile stresses in the concrete caused by external loads.
APPLICATIONS:
Prestressed concrete can be applied to almost all concrete constructions where ordinary reinforced concrete is used.
But due to high cost of prestressing & better quality of materials used, its use is made under special conditions, particularly for precast members.
In addition to structural precast members,eg. Joints,beams,slabs,columns,girders,etc,prestressed concrete is used for the framed multistoried block, such as offices,flats,hotels,hospitals,etc.
Also various types of industrial structures like silos,hangers,roof trusses, water tank,piles,pipes,factories,steel plants,etc. Can be built in prestressed concrete.
ADVANTAGES
The size or dimension of structural members are reduced. It permits the use of large spans greater than 30m, with shallow members, even when heavy loads are encountered. There is considerable saving in cost of supporting members & foundations. Because of controlled concrete & high tension steel being used & nullifying the effect of dead loads, smaller deflections are caused.
DISADVANTAGES
The unit cost of high strength materials being used is higher. Extra initial cost due to the use of prestressing equipment & its installation. Extra labour cost for prestressing.
Prestressing is uneconomical for short spans & light loads
TALL STRUCTURES SEMINAR REPORT
Reviewed by Mnz
on
8:39 AM
Rating:
Reviewed by Mnz
on
8:39 AM
Rating:
No comments: