Prestressed Concrete Structures MCQ Set 1
1. Which is more economical to use along precast reinforced concrete trusses?
a) Roller member
b) Hinge member
c) Tie member
d) Flange member
Answer: c [Reason:] It is more economical and convenient to use precast reinforced concrete trusses with a prestressed tie member covering roofs of industrial structures such as wave houses workshops having spans exceeding 15m.
2. The configuration of truss depends upon the shape of:
Answer: b [Reason:] The configuration of the truss depends up on the shape of the roof and its general layout and in Russia trusses are generally adopted for industrial buildings having spans greater than 18m and a central I girders and the deck is suspended by cable stays comprising parallel wire cables of BBR-HIAM type with their own anchorage system.
3. Which type of trusses in case of structure located in coastal areas?
b) Tensile trusses
c) Concrete trusses
d) Tensile & Concrete trusses
Answer: c [Reason:] In the case of structures located in coastal area where humidity and temperature are high, it is preferable to use concrete trusses in place of steel trusses which are vulnerable to rust and deterioration due to high humidity.
4. The use of concrete trusses will considerably reduce:
Answer: a [Reason:] The use of concrete trusses will considerably reduce the maintenance cost in comparison with steel trusses which require periodical painting at shorter intervals and the trusses in structural member are of circular, cylindrical, hollow etc used for various heavy structures the stress analysis is done by considering all the factors which influence the trusses.
5. Most favorable configuration of the top chord is obtained in:
a) Bow strung truss
b) Elevated truss
c) Curved truss
d) Termed truss
Answer: a [Reason:] The most favorable configuration of the top cord is obtained in the bow strung truss and the web or diagonal members are subjected to very heavy tension and hence ideally suited for prestressing and top chords and bottom chords are considered in case of precast and insitu cast concrete assuming the pretensioned beam as unpropped and propped.
6. The cables strayed bridges are preferred to convential suspension bridges due to reduction of:
b) Bending moment
Answer: b [Reason:] Cable strayed bridges are preferred to convential suspension bridges for long spans mainly due to reduction in bending moment in the stiffening girder resulting in smaller section of the girders leading to considerable economy in overall costs highway bridges can be built of prestressed concrete with spans up 700m and rail bridges up to span range of 400m.
7. The suspension bridges require a stiffening girder for covering the span, with a:
a) Flexural stiffness
b) Tensile stiffness
c) Compressive stiffness
d) Principle stiffness
Answer: a [Reason:] A comparative study also indicates that a suspension bridge requires a stiffening girder with a flexural stiffness girder with a flexural stiffness which must be about ten times larger than that required for a cable stayed bridge covering the same span and suspension bridge requires additional heavy anchor blocks which can be prohibitively costly if the navigation clearance is high and foundation conditions poor.
8. The second Hooghly bridge (vidyasagar sethu) at Kolkata is an excellent example of:
a) Cable strayed bridge
b) Cable tensioned bridge
c) Cable stressed bridge
d) Cable strained bridge
Answer: a [Reason:] The second Hooghly bridge (vidyasagar sethu) at Kolkata is an excellent example of: Cable strayed bridge comprising a main span of 457.2m and two side spans of 182.8m each and the deck is made of concrete slab 230mm thick two outer steel I girders 28.10m apart.
9. The bridge provides how many large carriage ways:
Answer: d [Reason:] The Bridge provides for two 3- lane carriage ways 12.3m each and 2.5m floor paths and the cable stayed bridge costing 600 million rupees was found to be cost effective in comparison with other types.
10. The world’s tallest and longest cable stayed bridge is located in:
Answer: b [Reason:] The world’s tallest and longest cables stayed bridge is located in France and the French bridge is considered to be an engineering feat since some of the bridge pillars rise gracefully to a height of more than 300m and the bridge is located outside the French town of milliance and is 2.46km long and the bridge designed by the famous British architecture sir norman Foster, is currently the world’s tallest and longest cable stayed bridge and described by many as an astounding engineering feat.
Prestressed Concrete Structures MCQ Set 2
1. The developments in the field of concrete mix design, gave compressive strength ranging between:
Answer: b [Reason:] Recent developments in the field of concrete mix design have indicated that it is now possible to produce even ultra high strength concrete, of any desired 28 day cube compressive strength ranging from 70-100n/mm2 without taking resource to unusual materials.
2. High strength concrete resists:
c) Tangent moments
d) Trapezoidal moments
Answer: b [Reason:] The concrete in a prestressed concrete member is subjected to high bearing stresses due to anchoring at its ends and hence, high strength concrete is required to safely resist the bursting stresses at the end of the beam.
3. In high strength concrete, high modulus of elasticity in the beam is due to:
a) Elastic and creep strains
b) Principle tensile stresses
c) Reinforced beams
Answer: a [Reason:] Low shrinkage, minimum creep characteristics and a high value of young’s modulus are generally deemed necessary for concrete used for prestressed members and the loss of prestress in steel reinforcement is minimum because the elastic and creep strain are very small due to high modulus of elasticity.
4. Which of the following is one of the standard codes used for designing high strength concrete mixes?
a) BS 8110-1985
b) BS 883-1974
c) BS 8113-1986
d) BS 886-1976
Answer: a [Reason:] The various methods adopted for designing high strength concrete mixes are Erntroy and Shack lock’s empirical method, American concrete institute method, British DOE method, Indian standard code and British code BS 8110-1985 stipulates that not more than 5 percent of the test results should fall below 28 days characteristic strength.
5. Which of the following is the Indian code used for high strength concrete mixes?
a) IS 1343-1980
b) IS 10263-1982
c) IS 384-1980
d) IS 457-1979
Answer: a [Reason:] Indian standard code IS 1343-1980 and IS 456-1978 stipulates that only controlled concrete should be used for prestressed concrete construction and the exact specifications with regard to the acceptance criteria for concrete generally vary from one code to another.
6. The cube strength of concrete required for both pre tensioning and post tensioning according to Indian standard codes are:
a) 30 and 20
b) 15 and 25
c) 40 and 30
d) 45 and 35
Answer: d [Reason:] The minimum 28 day cube compressive strength prescribed in the Indian standard code IS 1343-1980 is 45n/mm2 for pretensioned members and 35n/mm2 for post tensioned members with the development of vibration techniques in 1930, it became possible to produce without much difficult, high strength concrete having 28 day compression strength in the range of 30-70n/mm2.
7. The full form of ACI method for mix design proportion is:
a) American committee institute
b) American council institute
c) American concrete institute
d) American cement institute
Answer: c [Reason:] American concrete institute’s mix design procedure for no slump is one of the methods used for high strength concrete mix design and the American concrete institute in a non profit technical society and standards developing organization, ACI was founded in January 1905.
8. In which method, high strength concrete mixes are designed by relating compressive strength to reference number?
a) Erntroy and Shack locks
b) American concrete institute method
c) British DOE method
d) Indian standard code method
Answer: a [Reason:] In Erntroy and Shack lock’s empirical method high strength concrete mixes are designed by using empirical graphs relating the compressive strength to reference number for concrete made with crushed Granite, coarse aggregates and irregular gravel and the range of the degrees of workability varying from externally low to high corresponds to the compacting factor values of 0.65 and 0.95.
9. The water cement ratio used for British DOE method is:
Answer: b [Reason:] In British DOE method based on the type of cement and coarse aggregate provided evaluate the compressive strength of concrete mix made with water cement ratio of 0.5 and the durability requirements of mix design. Doe is design of experiments is a methodology that can be effective for general problem solving as well as for improving or optimizing product design and manufacturing and production process.
10. The degree of workability of Indian standard method is:
Answer: a [Reason:] The degree of workability relating to compaction factor value is 0.80 for Indian standard method design for high strength concrete mix, the steps involved in Indian standard method is target mean strength, water cement ratio, maximum size of aggregates, degree of workability, considering all the factors the cement content is obtained.
Prestressed Concrete Structures MCQ Set 3
1. The ultimate strength of high tensile steel is:
Answer: b [Reason:] High tensile steel are commonly used in prestressed concrete members and ultimate strength of high tensile steel is equal to 2100n/mm2, therefore the losses of prestress due to shrinkage and creep with a stress of 200n/mm2 are restricted.
2. The high tensile steel is obtained by increasing content of:
a) Carbon content in steel
b) Aluminium content in steel
c) Manganese content in steel
d) Sulphur content in steel
Answer: a [Reason:] High tensile steel is required in prestressed concrete member and it is obtained by increasing the carbon content in steel and the percentage of carbon is 0.6-0.85%, 0.7-1% of manganese, 0.05% of sulphur and phosphorus is present in high tensile steel.
3. The properties of cold-drawing through wires can be improved by heating at:
Answer: c [Reason:] As per IS:1785-1983, the nominal size of cold drawn stress are 2.5,3,4,5,7 and 8mm diameter and to improve the properties of wire, they have to be tempered by heating the wires at 150 to 480degrees, which enhances tensile strength.
4. Hard-drawn steel wires used in high tensile steel are considered as:
a) Crimped elements
b) Twisted elements
c) Durable elements
d) Tempered elements
Answer: a [Reason:] As per IS: 6003-1983, the diameter of wires are mostly used in strands of two, three or seven wires and they are considered as indented or crimped pretensioned element, due to their superior bond character and two and three ply strands, 2-3mm diameter wires are used whereas in 7 ply stand a diameter of 2-5mm wires are adopted and the nominal diameter of 7 ply stand varies in between 6.3 to 15.2mm.
5. The atomic hydrogen is liberated as a result of action of:
Answer: c [Reason:] Atomic hydrogen is liberated as a result of the action of acids on high-tensile steel and they penetrate into the steel surface making it brittle and fracture prone on being subjected to tensile stress and even small amounts of hydrogen can cause considerable damage to the tensile strength of high steel wires.
6. The prevention of hydrogen embrittlement can be done by protecting the wires from:
a) Rain water and humidity
b) Reactions and shocks
Answer: a [Reason:] In order to prevent hydrogen embrittlement, it is essential that the steel is properly protected from the action of acids and the wires should be protected from rain water and excessive humidity by storing them in dry conditions.
7. The permissible stress in prestressing steel should not exceed:
Answer: a [Reason:] The maximum tensile stress at initial tensioning time should not exceed 80 percent of ultimate tensile strength of wire and the yield stress for steel and the permissible unit bearing pressure on the concrete should not exceed 0.48Fr (A1/A2)1/2 after accounting for are all the losses due to creep of concrete, elastic shortening, relaxation of steel and seating of anchorages etc.
8. The nominal cover provided for moderate steel is:
Answer: a [Reason:] The covers may be reduced to 15mm provided that the nominal maximum size of aggregates does not exceed 15mm and the nominal cover provided for moderate steel is 30mm or the size of cable in the case of protected post tensioned members are exposed to an aggressive environment, these cover requirements are increased by 10mm.
9. The nominal cover provided for steel to obtain most effective fire resistance is according to:
Answer: a [Reason:] According to BSEN (British code): 1993-1-2004, nominal cover is provided for steel to obtain most effective fire resistance and durability and it is ability of the structural member to withstand the effect of fire without reaching any of the limit states.
10. The codal provision for reinforcement cover is?
a) IS: 1343-2012
b) IS: 1347-2014
c) IS: 1342-2006
d) IS: 1340-2008
Answer: a [Reason:] Reinforcement cover is provided according to codal provision IS:1343-2012 and it is essential to provide because it leads to corrosion, protecting steel from fire etc, the consequences of providing cover more than requirement leads to increase in width of cracks and weight of structure.
Prestressed Concrete Structures MCQ Set 4
1. In 1886, Jackson of San Francisco applied for a patent in which prestress was introduced by:
a) Tensioning the reinforced rods in sleeves
b) Tensioning the reinforced rings in sleeves
c) Tensioning the reinforced steel in sleeves
d) Tensioning the reinforced bars in sleeves
Answer: a [Reason:] In present state of development in the field of prestressed concrete is due to continuous research done by engineers and scientists in this field during the last 90 years while Jackson of San Francisco applied for a patent “construction of artificial stone and concrete pavements”, in which prestress was introduced by tensioning the reinforced rods set in sleeves.
2. In 1888, manufacturing of slabs and small beams using embedded tensioned wires in concrete was introduced by:
b) Karl marx
Answer: a [Reason:] Dohring of Germany manufactured slabs and small beams in 1888, using embedded tensioned wires in concrete to avoid cracks, in 1923 Emperger of Vienna developed a method for making wire bound reinforced concrete pipes, the use of unbounded tendons was first demonstrated by Dischinger in 1928 and Karl marx was a German philosopher, economist, political theorist, sociologist, journalist.
3. An engineer mandl in 1896 put forward the idea to counteract the stresses acting due to:
a) Bending moment
c) Twisting moment
Answer: d [Reason:] The idea of prestressing to counteract the stresses due to loads was first put forward by the Austrian engineer Mandl in 1896 while bending moment, tension and twisting moment were considered as the basic concepts in strength of materials and this is an extension to structures subject with a new idea of prestressing making adverse advantages to the future structures.
4. In 1907, the losses of prestress due to elastic shortening of concrete was developed by:
Answer: a [Reason:] Koenon of Germany developed the subject by reporting in 1907, on the losses of prestress due to elastic shortening of concrete and Steiner recognized the losses due to shrinkage of concrete around 1908.
5. The importance of using high strength concrete and high tensile steel was introduced by:
Answer: a [Reason:] Freyssinet in 1928-1933 has given the importance of using high strength concrete and steel in order to various losses of prestress due to creep and shrinkage and he also developed vibration technique to produce high strength concrete also manufactured double acting jack for stressing high tensile steel wires into the concrete structure.
6. The use of prestressed concrete in Europe and United states spread rapidly from?
Answer: b [Reason:] The use of prestressed concrete spread rapidly from 1935 onwards and many long span bridges, industrial shell roofs, marine structures, nuclear pressure vessels etc were constructed between 1945 and 1950 in Europe and United states.
7. In words of Guyon, more than a technique prestress is a:
c) Strong material
d) Life for structures
Answer: a [Reason:] In the words of Guyon: “there is no structural problem to which prestress cannot provide a solution, and often a revolutionary one, Prestress is more than a technique; it is a general principle” is the description or explanation given by Guyon on prestressing.
8. Dischinger explained the use of unbounded tendons in the construction of:
a) Large bridges
b) Small bridges
Answer: a [Reason:] Dischinger in 1928, has explained the use of unbounded tendons in the construction of large bridges of deep girder type by this method, the losses of prestress are neutralized by placing the prestressing wires inside the girder without any bond.
9. Vienna developed the method of wire bound reinforced concrete pipe by binding high tensile steel wires, the stresses in that were ranging in between:
a) 170 to 900
b) 100 to 800
c) 160 to 800
d) 140 to 200
Answer: c [Reason:] Vienna in 1923, has developed a wire bound reinforced concrete pipe by binding high tensile steel wires on pipe and In this method it was noticed that the stresses of concrete was ranging in between 160 to 800 n/mm2.
10. Prestressed concrete is widely used in construction by:
b) Bore wells
d) Nuclear pressure vessels
Answer: d [Reason:] Prestressed concrete is used in construction of long span bridges, industrial roofs, marine structures, nuclear pressure vessels, water retaining structures, railway sleepers etc and it also has a higher modulus of elasticity and small creep strain, resulting in smaller loss of prestressing in the steel while prestressed concrete is one of the construction material in building and bridge products around the world.
Prestressed Concrete Structures MCQ Set 5
1. The logical steps to be found before beginning the construction of any prestressed concrete structures are:
a) Planning analysis and design
b) Stress analysis
c) Strain analysis
d) Prestressed analysis
Answer: a [Reason:] Planning, analysis and design are the logical steps to be followed before beginning the construction of any prestressed concrete structures from ancient times; construction of a structure has always been one of the most fascinating challenges to man ingenuity.
2. The architectural capabilities constitutes the essence of the
a) Conceptual aspects of structures
b) Chemical aspects of structures
c) Structural aspects of structures
d) Time aspects of structures
Answer: b [Reason:] Architectural capabilities constitutes the essence of the conceptual and aesthetic aspects of structures and the domain of construction activity involves several known and unknown features such as management of materials and labour, mobilization of suitable cost effective techniques, treacherous foundations problems adverse water conditions, planning and scheduling of the construction process to a time based frame, constant interaction with the design engineer, architect, site engineer, construction workers and ability to take sound and daring decisions at times of crisis.
3. Which type of engineers should be more conceptual and visual?
a) Construction engineers
b) Site engineers
c) Practical engineers
Answer: c [Reason:] Practical engineers must be more conceptual than mere perceptual, more creative than mere analytical and more visual than mere mathematical and construction engineers should have wide experience involving several types of structures rather than isolated narrow specialization and expertise and original skill are attained from relentless understanding and practice rather than mere theoretical knowledge and good and sound judgment are attained from wide practical experience and often experience comes from bad judgment.
4. The sub structure in every structure is known as:
Answer: b [Reason:] Every structure has a foundation(sub structure) which may either be shallow type, like isolated and combined footings, or a monolithic raft where the loads to be transferred on solids of low bearing capacity and large, as in the case of multistoried buildings.
5. Deep foundation depends upon the type of:
a) Super structure
Answer: a [Reason:] Deep foundations are generally piles, caissons and walls depending upon the type of super structure and the soil conditions and the most common types of piles used are: Timber, Steel, Reinforced concrete and prestressed concrete.
6. The precast piles of reinforced concrete are widely used types for:
a) Plastic solids
b) Wet soils
c) Clayey soils
d) Hard soils
Answer: c [Reason:] Precast piles of reinforced or prestressed concrete are the most widely used types for clayey soils of low bearing capacity and well foundation also referred to as open caissons are the most common types generally adopted for major bridges in India, where the soil strata comprises sand or stiff clay.
7. The pneumatic caisson foundations consisting of:
a) Concrete cutting
b) Steel cutting
c) Aluminium cutting
d) Block cutting
Answer: b [Reason:] Pneumatic caisson foundations consisting of steel cutting base and concrete pier are adopted for deep foundations in watery situation and the reader may refer to the monograph design of bridges by the author for detailed descriptions and structural design of piles, wells and caissons.
8. One of the following elements of super structure:
a) Aircraft hanger
b) Water vessels
c) Hydrogen container
d) Liquid container
Answer: a [Reason:] A super structure comprises a floor or roof of a building, bridge deck, large capacity liquid retaining structure, aircraft hanger, nuclear reactor containment vessel, offshore oil drilling platform and a host type of structures and there is no single form of design which would always be more economical.
9. There is no single form of design which would always be most:
a) Long lasting
Answer: b [Reason:] There is no single form of design which would always be most economical and it is only by computing a few tentative with a knowledge of the site conditions, availability of skilled labour, materials and machinery, time frame fixed for completion of the project and purpose of the intended structure that one can reasonably arrive at an economical solution.
10. The specifications for batching and mixing of concrete are measured to an accuracy of:
Answer: a [Reason:] Concrete of uniform quality can be produced only when the ingredients are accurately measured for each batch and good specification requires that batching is done by weight rather than by volume weight batching ensures greater accuracy, simplicity and flexibility and specifications require that the materials – cement, aggregates and water measured to an accuracy of + or – 0.5%.