Define Prestressed concrete and state types of prestressing steel.

Define Prestressed concrete and state types of prestressing steel.
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1 Answer

Answer :

Prestressed concrete: Prestressed concrete is basically a concrete in which internal stresses of a suitable magnitude and distribution are deliberately introduced so that the stresses resulting from external loads are counteracted to a desired degree.

Types of pre-stressing steel

1) Plain hard-drawn steel wire conforming to IS: 785(Part 1)-1966 and

IS: 1785(Part 2)-1967,

2) Cold-drawn indented wire

3) High tensile steel bar conforming to IS: 2090- 1962, and.

4) Uncoated stress relieved strand conforming to IS: 6006-1970. 
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Related questions

State the advantages and disadvantages of prestressed concrete.

Description : State the advantages and disadvantages of prestressed concrete.

Last Answer : Advantages: 1. The c/s ismore efficiently used in fully prestressed members. 2. Dead loads are reduced considerably. 3. Improved shear resistance, due to the effect of compressive prestress, ... cube strength of 35 N/mm2 for Posttensioned system and 45 N/ mm2 for pretensioned system.

Justify the necessity of use of high-grade materials in prestressed concrete.

Description : Justify the necessity of use of high-grade materials in prestressed concrete.

Last Answer : 1) If mild steel is used, the working stress in it (i.e. 140 N/mm2) is more or less completely lost due to elastic deformation, creep and shrinkage of concrete. 2) The ... structural elements. With reduced dead weight of the material, larger spans become technically and economical practicable. 

What is the basic principle of Prestressed concrete?

Description : What is the basic principle of Prestressed concrete?

Last Answer : Principle: The compressive stresses induced by high strength steel tendons in a concrete member before the application of load, will balance the tensile stresses imposed in the member during its service.

Explain freyssinet system of prestressing with respect to process and application with sketches.

Description : Explain freyssinet system of prestressing with respect to process and application with sketches.

Last Answer : Process: - 1. The freyssinet system was the first to be introduced among the post - tensioned system high tensile steel wires 5mm to 8mm diameter about 12 in number are arranged to form a group into a cable ... gas (LNG) storage tank 4. Off share platforms. 5. Wind turbine towers etc.

State any four advantages and four disadvantages of precast concrete.

Description : State any four advantages and four disadvantages of precast concrete.

Last Answer : Advantages: 1. Very rapid speed of erection 2. Good quality control 3. Entire building can be precast-walls, floors, beams, etc. 4. Rapid construction on site 5. High quality because of ... is required in the application of the panel on site. 11. Cranes are required to lift panels.

State any two names of materials used in precast concrete

Description : State any two names of materials used in precast concrete

Last Answer : 1. Cement 2. Sand 3. Steel 4. Water 5. Polystyrene 6. Fly ash. 7. Ground granulated blast furnace slag

Define Modules and modular co-ordination

Description : Define Modules and modular co-ordination

Last Answer : Modules: Modules are a standard unit of size used to coordinate the dimensions of buildings and components. They are of two types: 1. Multi modules 2. Basic modules  Modular Co-ordination: The modular ... for basic module is M 1M = 100mm 100 mm = 1M = It is international standard value.

A simply supported rectangular beam is uniformly loaded and is prestressed. The tendon provided for prestressing should be (a) Straight, above centroidal axis (b) Straight, below centroidal axis (c) parabolic, with convexity upward (d) Parabolic, with convexity downward

Description : A simply supported rectangular beam is uniformly loaded and is prestressed. The tendon provided for prestressing should be (a) Straight, above centroidal axis (b) Straight, below centroidal axis (c) parabolic, with convexity upward (d) Parabolic, with convexity downward

Last Answer : (d) Parabolic, with convexity downward

List the various types of losses of prestress in pretensioned pre-stressed member.

Description : List the various types of losses of prestress in pretensioned pre-stressed member.

Last Answer : i. Elastic shortening ii. Shrinkage of concrete iii. Creep of concrete iv. Relaxation of steel

Explain the loss of prestress due to friction and slip of anchorage and state two remedial measures to avoid them.

Description : Explain the loss of prestress due to friction and slip of anchorage and state two remedial measures to avoid them.

Last Answer : Loss due to Friction: This loss occurs only in post-tensioned members. There always exists a certain amount of friction in the jacking and anchoring system and on the walls of the duct. So, ... over-extending the tendon in the prestressing operation by the amount of the draw - in before anchoring

Explain determination of Water absorption of paver block and state acceptable limits as per IS.

Description : Explain determination of Water absorption of paver block and state acceptable limits as per IS. 

Last Answer : Step 1. Saturation  The test specimen shall be completely immersed in water at room temperature for 24 * 2 h. The specimen then shall be removed from the water and allowed to drain for 1 min by ... more than 6 % by mass and in individual samples, the water absorption should be restricted to 7 %

State cable profile in simply supported rectangular beam section.

Description : State cable profile in simply supported rectangular beam section.

Last Answer : Cabe profile: In a prestressed concrete member, external type of loads is balanced by transverse component of suitable cable profile, on effect of loading the net deformation increases the stress, strain and length of the tendon, extension of tendon, increase in strain, increase in stress.

State any four precast non-structural components that can be used for speedy construction.

Description : State any four precast non-structural components that can be used for speedy construction.

Last Answer : 1. Architectural Precast 2. Insulated Architectural Cladding 3. Insulated Wall Panels 4. Column Covers 5. Precast Concrete Light Wall 6. Precast Concrete Spandrels 7. Precast Concrete Solid Walls 8. Stormwater Deflector 9. Façade 10. Concrete panels for partition walls 11. Concrete planks

For what type of structures do you recommend post-tensioning?

Description : For what type of structures do you recommend post-tensioning?

Last Answer : 1) High rise buildings. In long span slab where beam is not provided & the slab of assembly hall, cinema theaters etc. like structure where the distance between columns are more, then post ... Post Tensioning is used extensively for slabs on grade where soils are likely to move (expansive soils)

Depict the effect of pre-fabricated building on the surrounding environment with respect to noise pollution, staking at elements and transportation.

Description : Depict the effect of pre-fabricated building on the surrounding environment with respect to noise pollution, staking at elements and transportation. 

Last Answer : Noise pollution is the serious or more noise that may damage the activity or human life. The contribution of most outside noise is mainly due to building activities. Noise pollution affects both health and ... iv) Sleep interference v) Habit of talking loudly vi) Hearing loss vii) Concentration

Illustrate cable profiles for eccentric straight and parabolic cables with sketches.

Description : Illustrate cable profiles for eccentric straight and parabolic cables with sketches. 

Last Answer : i) Eccentric straight cable profile: The stress due to prestressing alone are generally combined stresses due to the action of direct load bending from an eccentrically applied load. In this case, the load is ... section as shown in the figure below. ii) Parabolic cable profile

Explain any one method of Prefab system.

Description : Explain any one method of Prefab system.

Last Answer : Prefab system: It refers to any part of a building that has been fabricated at a place other than its final location. For this reason, it can be referred to by other names such as off-site fabrication, ... If you need further assessing, feel free to contact us; your needs are all that matter to us.

Explain the procedure of the storage, transportation and erection of prefabricated building elements.

Description : Explain the procedure of the storage, transportation and erection of prefabricated building elements. 

Last Answer : Storage of pre-fabricated building elements: 1) Procurement storage of Unloading raw materials 2) Testing of raw materials 3) Design of concrete mix 4) Fabrication of reinforcement cages 5) ... differs with risk condition, hence skilled foremen, and workers to be employed on the job.

Describe with sketch any two joints in doors and window frame.

Description : Describe with sketch any two joints in doors and window frame.

Last Answer : 1. Connections must be adequate structurally. 2. Means of connections between adjacent must allow safe and speedy erection regardless of minor inherent inaccuracies in precast elements and in-situ concrete. 3. ... height) of the frames shall confirm to the requirements of IS : 4021-1976

Describe any two design considerations for Precast Canal lining.

Description : Describe any two design considerations for Precast Canal lining.

Last Answer : 1. Precast concrete slabs, laid properly on carefully prepared sub-grades and with the joints, effectively sealed, constitute a serviceable type of lining. The precast slabs are about 5 to ... . However, seepage losses are obviously more. Transportation of precast slabs may contribute to breakage. 

A prestressed concrete section is said to have failed in strength at the moment when all the material in the section has exhausted its (a) Stress limitations (b) Strain limitations (c) Stress as well as strain limitations (b) Laad limitations

Description : A prestressed concrete section is said to have failed in strength at the moment when all the material in the section has exhausted its (a) Stress limitations (b) Strain limitations (c) Stress as well as strain limitations (b) Laad limitations

Last Answer : (a) Stress limitations

Inc case of prestressed concrete members, the bursting stresses develop at (a) Bond zone (b) Maximum bending moment zone (c ) Maximum shear stress zone (d) Anchorage zone

Description : Inc case of prestressed concrete members, the bursting stresses develop at (a) Bond zone (b) Maximum bending moment zone (c ) Maximum shear stress zone (d) Anchorage zone

Last Answer : (d) Anchorage zone

In prestressed concrete members, the shear force depends upon (a) Distributed load (b) Torsion (c) Concentrated load (d) Variation in net bending moment

Description : In prestressed concrete members, the shear force depends upon (a) Distributed load (b) Torsion (c) Concentrated load (d) Variation in net bending moment

Last Answer : (d) Variation in net bending moment

The system in which high tensile alloy steel bars (silica manganese steel) are used as prestressing tendons, is known as (A) Freyssinet system (B) Magnel-Blaton system (C) C.C.L. standard system (D) Lee-McCall system

Description : The system in which high tensile alloy steel bars (silica manganese steel) are used as prestressing tendons, is known as (A) Freyssinet system (B) Magnel-Blaton system (C) C.C.L. standard system (D) Lee-McCall system

Last Answer : Answer: Option D

What are the three major types of reinforcement used in prestressing?

Description : What are the three major types of reinforcement used in prestressing?

Last Answer : i) Spalling reinforcement Spalling stresses are established behind the loaded area of anchor blocks and this causes breaking away of surface concrete. These stresses are induced by strain incompatibility with ... of action of the load. Reinforcement is needed to resist these lateral tensile forces.

In prestressing work, if more than one wire or strand is included in the same duct, why should all wires/strands be stressed at the same time?

Description : In prestressing work, if more than one wire or strand is included in the same duct, why should all wires/strands be stressed at the same time?

Last Answer : If wires/strands are stressed individually inside the same duct, then those stressed strand/wires will bear against those unstressed ones and trap them. Therefore, the friction of the trapped wires is high and is undesirable.

Under what situation shall engineers use jacking at one end only and from both ends in prestressing work?

Description : Under what situation shall engineers use jacking at one end only and from both ends in prestressing work?

Last Answer : During prestressing operation at one end, frictional losses will occur and the prestressing force decreases along the length of tendon until reaching the other end. These frictional losses include the ... if the total span length is sufficiently long, jacking from both ends should be considered.

In case of Magnel- Blaton system of prestressing, each sandwich plate can generally anchor (a) 6 wires (b) 8 wires (c) 10 wires (d) 16 wires

Description : In case of Magnel- Blaton system of prestressing, each sandwich plate can generally anchor (a) 6 wires (b) 8 wires (c) 10 wires (d) 16 wires

Last Answer : (a) 6 wires

What Reinforcements Are Used In The Process Of Prestressing?

Description : What Reinforcements Are Used In The Process Of Prestressing?

Last Answer : Answer : The major types of reinforcements used in prestressing are:  Spalling Reinforcement: The spalling stresses leads to stress behind the loaded area of the anchor blocks. This results in the ... of load. In order to reduce such stresses reinforcements in the form of bursting is required.

In a curved prestressed bridge, how should the guided bearings in piers of the curved region be oriented with respect to the fixed bearing in abutment?

Description : In a curved prestressed bridge, how should the guided bearings in piers of the curved region be oriented with respect to the fixed bearing in abutment?

Last Answer : To determine the orientation of guided bearings, one should understand the movement of curved region of a prestressed bridge. Movement of prestress and creep are tangential to the curvature of the ... large, temporary freedom of movement at the guided bearings has to be provided during construction.

For a certain set of external loads, concordant profile in a prestressed beam represents to some scale the (a) Influence line diagram (b) Shear force diagram (c) Bending moment diagram (d) Williot-Mohr diagram

Description : For a certain set of external loads, concordant profile in a prestressed beam represents to some scale the (a) Influence line diagram (b) Shear force diagram (c) Bending moment diagram (d) Williot-Mohr diagram

Last Answer : (c) Bending moment diagram

Discuss the advantages and limitation of prestressed bridge.

Description : Discuss the advantages and limitation of prestressed bridge.

Last Answer : Advantages of Prestressed Bridge 1) Have higher load carrying capacity 2) Fewer expansion joints 3) Reduced deflection of girders. 4) Lighter construction. 5) More aesthetic appearance. 6) More ... steel results in high cost. 2) Skill supervision required. 3) Special equipment is required.

Define the following special types of concretes with its one use. i) Vacuum concrete ii) Fiber reinforced concrete iii) High performance concrete iv) Self-compacting concrete

Description : Define the following special types of concretes with its one use. i) Vacuum concrete ii) Fiber reinforced concrete iii) High performance concrete iv) Self-compacting concrete

Last Answer : The uses of special types of concretes are as follows.  i) Vacuum concrete: It is the concrete in which entrained air and excess water form concrete mix is taken out from vacuum pump, ... . large bridge and machine foundations iii. Pumped concrete for floors and slabs. iv. Pre-stressed concrete

Consider the following statements: Percentage of steel for balanced designed of a singly reinforced rectangular section by limit state method depends on (1) Characteristic strength of concrete (2) Yield strength of concrete (3) Modulus of elasticity of steel (4) Geometry of the section. Which of these statements are correct? (a) 2, 3 and 4 (b) 1, 3 and 4 (c) 1, 2 and 4 (d) 1, 2 and 3

Description : Consider the following statements: Percentage of steel for balanced designed of a singly reinforced rectangular section by limit state method depends on (1) Characteristic strength of concrete (2) Yield strength of concrete (3) Modulus of elasticity ... (b) 1, 3 and 4 (c) 1, 2 and 4 (d) 1, 2 and 3

Last Answer : 1,2,4

In Limit state method of design, the factor of safety for concrete and steel respectively are [ A ] 3.00 and 1.80 [ B ] 1.50 and 1.18 [ C ] 1.50 and 1.15 [ D ] 1.50 and 1.50

Description : In Limit state method of design, the factor of safety for concrete and steel respectively are [ A ] 3.00 and 1.80 [ B ] 1.50 and 1.18 [ C ] 1.50 and 1.15 [ D ] 1.50 and 1.50

Last Answer : [ C ] 1.50 and 1.15

In order to figure out what is in a sealed box, you perform some tests. The box seems heavy for its size and is harder to remove from a steel table than when placed on a concrete floor. What kind of object could be inside the box?' -Riddles

Description : In order to figure out what is in a sealed box, you perform some tests. The box seems heavy for its size and is harder to remove from a steel table than when placed on a concrete floor. What kind of object could be inside the box?' -Riddles

Last Answer : The answer is magnet because it would be really hard to move a magnet across a steel table since it would attract to the steel-not making it able to move.

square cross section b/h/h'=400/400/40mm with a reinforcement ratio of p=0.015 is loaded for action forces of axial load plus uniaxial bending.the column is to be made of C25/30 concrete & S-460 steel.check whether the column AB is short or long?

Description : square cross section b/h/h'=400/400/40mm with a reinforcement ratio of p=0.015 is loaded for action forces of axial load plus uniaxial bending.the column is to be made of C25/30 concrete & S-460 steel.check whether the column AB is short or long?

Last Answer : 10001/999900

Do I need a concrete slab foundation for a steel storage shed?

Description : Do I need a concrete slab foundation for a steel storage shed?

Last Answer : No, although that would be great there are other options. You may also build a wooden foundation and it will work just as well.

Which of the following is not a good moderating material? (A) Concrete (B) Boron (C) 18/8 stainless steel (D) All (A), (B) and (C)

Description : Which of the following is not a good moderating material? (A) Concrete (B) Boron (C) 18/8 stainless steel (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Pebble mills are tumbling mills widely used for grinding in the manufacture of paints & pigments and cosmetic industries, where iron contamination in the product is highly objectionable. Pebbles used in pebble mill are made of (A) Bronze (B) Stainless steel (C) Flint or porcelain (D) Concrete

Description : Pebble mills are tumbling mills widely used for grinding in the manufacture of paints & pigments and cosmetic industries, where iron contamination in the product is highly objectionable. Pebbles used in pebble mill are made of (A) Bronze (B) Stainless steel (C) Flint or porcelain (D) Concrete

Last Answer : (C) Flint or porcelain

The fermenter used for the production of ethyl alcohol from molasses is made of (A) Wood (B) Concrete (C) Copper bearing steel (D) Porcelain

Description : The fermenter used for the production of ethyl alcohol from molasses is made of (A) Wood (B) Concrete (C) Copper bearing steel (D) Porcelain

Last Answer : (C) Copper bearing steel

Thermal shield used in high powered nuclear reactor to protect the walls of the reactor from radiation damage is made of (A) Concrete (B) Steel (C) Zircaloy (D) Graphite

Description : Thermal shield used in high powered nuclear reactor to protect the walls of the reactor from radiation damage is made of (A) Concrete (B) Steel (C) Zircaloy (D) Graphite

Last Answer : (B) Steel

Soap kettle used in the production of laundry soap is made of (A) Steel with top section nickel clad or stainless steel (B) Cast iron (C) Nickel (D) Concrete

Description : Soap kettle used in the production of laundry soap is made of (A) Steel with top section nickel clad or stainless steel (B) Cast iron (C) Nickel (D) Concrete

Last Answer : (A) Steel with top section nickel clad or stainless steel

H2SO4 (< 50% concentration) is corrosive to (A) Aluminium, mild steel, stainless steel, concrete & tin (B) Copper, cast iron & high silicon iron (14% Si) (C) Rubber (butyl and hard), silicone rubber & Teflon (D) Glass, graphite, porcelain & stoneware

Description : H2SO4 (< 50% concentration) is corrosive to (A) Aluminium, mild steel, stainless steel, concrete & tin (B) Copper, cast iron & high silicon iron (14% Si) (C) Rubber (butyl and hard), silicone rubber & Teflon (D) Glass, graphite, porcelain & stoneware

Last Answer : (A) Aluminium, mild steel, stainless steel, concrete & tin

In the Kraft process of sulphate paper pulp manufacture, the black liquor and the white liquor storage tank is made of (A) Concrete (B) Wood (C) Steel (D) Porcelain

Description : In the Kraft process of sulphate paper pulp manufacture, the black liquor and the white liquor storage tank is made of (A) Concrete (B) Wood (C) Steel (D) Porcelain

Last Answer : (C) Steel

Copper is dissolved from its ore by H2SO4 in a percolation tank made of (A) Wood (B) Stainless steel (C) Reinforced concrete lined with lead (D) High silicon iron (14% Si)

Description : Copper is dissolved from its ore by H2SO4 in a percolation tank made of (A) Wood (B) Stainless steel (C) Reinforced concrete lined with lead (D) High silicon iron (14% Si)

Last Answer : (C) Reinforced concrete lined with lead

Cast iron detachable joint is used in __________ pipes. (A) Steel (B) Cast iron (C) Asbestos cement (D) Reinforced cement concrete

Description : Cast iron detachable joint is used in __________ pipes. (A) Steel (B) Cast iron (C) Asbestos cement (D) Reinforced cement concrete

Last Answer : (A) Steel

Steel rods are used in reinforced concrete to increase its __________ strength. (A) Shear (B) Tensile (C) Compressive (D) None of these

Description : Steel rods are used in reinforced concrete to increase its __________ strength. (A) Shear (B) Tensile (C) Compressive (D) None of these

Last Answer : (B) Tensile

Biological shield in a nuclear power reactor is made of (A) Concrete(B) Steel(C) Cadmium(D) Zircaloy

Description : Biological shield in a nuclear power reactor is made of (A) Concrete (B) Steel (C) Cadmium (D) Zircaloy

Last Answer : (A) Concrete

If a concrete column 200 × 200 mm in cross-section is reinforced with four steel bars of 1200 mm2 total cross-sectional area. Calculate the safe load for the column if permissible stress in concrete is 5 N/mm2 and Es is 15 Ec (A) 264 MN (B) 274 MN (C) 284 MN (D) 294 MN

Description : If a concrete column 200 200 mm in cross-section is reinforced with four steel bars of 1200  mm2  total cross-sectional area. Calculate the safe load for the column if permissible stress in  concrete is 5 N/mm2 ... 15 Ec (A) 264 MN  (B) 274 MN  (C) 284 MN  (D) 294 MN 

Last Answer : (C) 284 MN