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Question 1
ప్రశ్న 1
Which statement best describes the fundamental design objective of an isolated reinforced concrete footing?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
An RCC footing must safely transmit the applied loads, moments and forces to the supporting ground. IS 456 requires the induced reactions to be considered and the safe bearing capacity of the soil not to be exceeded. The arrangement should also promote settlement that is as nearly uniform as practicable. Structural checks of the footing itself are then made for bending, shear, anchorage and load transfer. Therefore Option A is correct.
వివరణ:
Question 2
ప్రశ్న 2
In conventional foundation terminology, which statement correctly distinguishes gross and net foundation pressure?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Gross contact pressure refers to the total contact pressure developed at the footing-soil interface under the loads included in the gross-pressure calculation. Net foundation pressure represents the increase over the pre-existing overburden pressure at the founding level. Hence net pressure is conventionally obtained by subtracting that overburden pressure from the corresponding gross pressure. The allowable soil value used in sizing must be matched consistently with whether it is stated on a gross or net basis. Therefore Option A is correct.
వివరణ:
Question 3
ప్రశ్న 3
A concentrically loaded footing is to be sized using an allowable gross soil pressure of 250 kN/m² at service load. The total service vertical load, including the footing weight and other loads included in the gross-pressure check, is 1800 kN. What minimum plan area is required?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Because the stated allowable bearing pressure is a service-level gross value, it is compared with the corresponding total service load. The required area is 1800/250 = 7.20 m². This calculation is a bearing-pressure sizing check rather than the factored structural strength design of the footing slab. A practical footing plan would normally be selected at or above this required area and then checked for structural actions. Therefore Option B is correct.
వివరణ:
Question 4
ప్రశ్న 4
A 3.0 m × 3.0 m footing carries a concentric factored total vertical load of 2250 kN, and the load is assumed to produce uniform factored soil reaction over the whole base. What factored soil pressure is used for the structural footing calculation?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The footing area is 3.0 × 3.0 = 9.0 m². Under the stated concentric and uniform-reaction assumption, the factored pressure is the factored vertical load divided by the footing area. Thus qu = 2250/9 = 250 kN/m². This upward factored pressure is then used to obtain design bending moments and shears for the stated structural idealization. Therefore Option C is correct.
వివరణ:
Question 5
ప్రశ్న 5
A centrally placed 400 mm square column is supported by a 2.60 m square footing. What is the footing projection beyond each face of the column?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a concentric square footing, the projection is half the difference between the footing side and the column side. The difference is 2.60 - 0.40 = 2.20 m. Dividing by two gives a projection of 1.10 m beyond each column face. This projection acts as the cantilever length used in simple footing moment and one-way shear calculations. Therefore Option C is correct.
వివరణ:
Question 6
ప్రశ్న 6
For an isolated concrete footing supporting a reinforced concrete column, where is the critical section for the greatest bending moment taken under IS 456?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
IS 456 specifies the bending moment at a section by considering the forces acting on the footing area on one side of a vertical plane through that section. For a footing supporting a concrete column, pedestal or wall, the greatest design bending moment is taken at the face of that support. This reflects the cantilever-type action of the footing projection beyond the column face. The one-way shear and punching-shear critical sections are located differently and should not be confused with the bending section. Therefore Option C is correct.
వివరణ:
Question 7
ప్రశ్న 7
A one-metre-wide strip of a footing projects 1.10 m beyond the face of a column and carries a uniform factored upward soil pressure of 200 kN/m². What design bending moment occurs at the column face for this strip?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a one-metre strip, the uniform upward line load is numerically 200 kN/m. The projection beyond the column face behaves as a cantilever of length 1.10 m for this simplified moment calculation. The moment at the fixed face is wL²/2 = 200 × 1.10²/2. This equals 121 kN·m per metre width. Therefore Option B is correct.
వివరణ:
Question 8
ప్రశ్న 8
An M25 footing strip 1000 mm wide has effective depth d = 450 mm and must resist Mu = 121 kN·m/m using Fe500 tension reinforcement. Using the singly reinforced Limit State equations and ignoring the separate minimum-steel check for this calculation, what Ast is required approximately?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For the one-metre strip, force equilibrium gives xu = 0.87fyAst/(0.36fckb). The moment equation is Mu = 0.87fyAst(d - 0.42xu). Substituting b = 1000 mm, d = 450 mm, fck = 25 N/mm², fy = 500 N/mm² and Mu = 121 kN·m gives Ast of about 636 mm²/m. The result must still be compared with the minimum reinforcement and detailing requirements applicable to the footing. Therefore Option B is correct.
వివరణ:
Question 9
ప్రశ్న 9
A 520 mm thick RCC footing uses Fe500 deformed bars. If only the solid-slab minimum reinforcement requirement governs in a particular direction, what minimum steel area is required per metre width?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
IS 456 states that minimum reinforcement and spacing in footings are to satisfy the requirements applicable to solid slabs. For high-strength deformed bars, the slab minimum is 0.12 percent of the gross cross-sectional area. For a one-metre strip of a 520 mm thick footing, this is 0.0012 × 1000 × 520 = 624 mm²/m. A larger area must be supplied whenever the flexural design requires more reinforcement. Therefore Option C is correct.
వివరణ:
Question 10
ప్రశ్న 10
What minimum nominal concrete cover is specifically prescribed by IS 456 for reinforcement in footings?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
IS 456 contains a specific nominal-cover provision for footings. It requires a minimum cover of 50 mm for footing reinforcement. This requirement is distinct from the ordinary slab cover values that may apply to suspended slabs in different exposure conditions. Adequate cover is especially important because footing concrete is close to or in contact with soil and moisture. Therefore Option C is correct.
వివరణ:
Question 11
ప్రశ్న 11
Which pair correctly states the IS 456 minimum edge thickness for ordinary footings on soil and the minimum thickness above the tops of piles for footings on piles?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
IS 456 specifies a minimum thickness at the edge of both reinforced and plain concrete footings. For footings on soil, the edge thickness is not to be less than 150 mm. For footings supported on piles, the thickness above the tops of the piles is not to be less than 300 mm. These are minimum geometric provisions and do not remove the need for a larger depth when bending, shear, anchorage or durability governs. Therefore Option B is correct.
వివరణ:
Question 12
ప్రశ్న 12
After considering the applicable amendment to IS 456, where is the critical vertical section for one-way shear in a footing measured from the face of the column, pedestal or wall?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The original printed wording of Clause 34.2.4.1(a) was supplemented by Amendment No. 1. For a footing on soil, the wide-beam or one-way shear section is located at a distance equal to the effective depth d from the face of the column, pedestal or wall. For a footing on piles, the corresponding distance is one-half of the effective depth. The two locations must therefore not be interchanged. Therefore Option A is correct.
వివరణ:
Question 13
ప్రశ్న 13
A footing on soil projects 1.10 m beyond a column face, has effective depth d = 450 mm, and carries a uniform factored upward pressure of 200 kN/m². What one-way shear force acts at the critical section per metre width?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a footing on soil, the critical one-way shear section is located one effective depth from the column face. The soil-loaded length outside that section is 1.10 - 0.45 = 0.65 m. For a one-metre-wide strip, the shear is therefore 200 × 0.65 × 1 = 130 kN. This is the factored shear force to be used in the nominal one-way shear-stress calculation for the stated strip. Therefore Option C is correct.
వివరణ:
Question 14
ప్రశ్న 14
For the footing strip in the previous question, V = 130 kN, b = 1000 mm and d = 450 mm. What nominal one-way shear stress τv = V/(bd) is obtained?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The nominal one-way shear stress is calculated as V/(bd). Substituting V = 130000 N, b = 1000 mm and d = 450 mm gives 130000/(1000 × 450). The result is approximately 0.289 N/mm². This value is then compared with the applicable design shear strength of concrete for the reinforcement percentage and concrete grade. Therefore Option C is correct.
వివరణ:
Question 15
ప్రశ్న 15
For punching or two-way shear around an interior column in an isolated footing, where is the basic critical perimeter located under the IS 456 provisions referenced for footing shear?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
IS 456 directs two-way footing shear design to the appropriate flat-slab shear provisions. The basic critical section is located at a distance d/2 from the periphery of the column or loaded area. In plan, the critical perimeter is geometrically similar to the support for the ordinary interior case. This differs from the one-way shear section, which for a footing on soil is located at distance d from the support face. Therefore Option B is correct.
వివరణ:
Question 16
ప్రశ్న 16
A 400 mm square column is supported on a footing having effective depth d = 450 mm. For an interior punching-shear check, what is the critical perimeter b0 at d/2 from the column face?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Moving the critical section d/2 outward from each face increases the side length of the critical square by a total distance d. The critical-section side is therefore 0.40 + 0.45 = 0.85 m. Its perimeter is 4 × 0.85 = 3.40 m. This b0 value is used with the effective depth in the punching shear stress expression V/(b0d). Therefore Option C is correct.
వివరణ:
Question 17
ప్రశ్న 17
A square-column footing has Pu = 1300 kN acting downward, uniform factored upward soil pressure qu = 200 kN/m², column size 400 mm × 400 mm, and effective depth d = 450 mm. Ignoring footing self-weight within this local calculation because Pu and qu are given directly, what punching shear stress acts at the d/2 critical perimeter approximately?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The critical square side is 0.40 + 0.45 = 0.85 m, so the area inside the critical perimeter is 0.85² = 0.7225 m². The upward soil reaction inside that area is 200 × 0.7225 = 144.5 kN, giving punching shear V = 1300 - 144.5 = 1155.5 kN. The critical perimeter is 3.40 m, or 3400 mm, and τv = 1155.5 × 10^3/(3400 × 450). This evaluates to approximately 0.755 N/mm². Therefore Option C is correct.
వివరణ:
Question 18
ప్రశ్న 18
For an interior footing with a square column and M25 concrete, what is the IS 456 punching-shear stress limit without shear reinforcement under the referenced flat-slab provision?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For punching shear without shear reinforcement, the limit is ksτc, where τc = 0.25√fck in Limit State design. The shape factor is ks = 0.5 + βc but not greater than 1.0, with βc equal to the short-side to long-side ratio of the column. For a square column βc = 1.0, so ks is capped at 1.0. With M25 concrete, 0.25√25 = 1.25 N/mm². Therefore Option C is correct.
వివరణ:
Question 19
ప్రశ్న 19
A 300 mm × 900 mm rectangular column bears on an M25 footing. Using the IS 456 punching-shear shape factor ks = 0.5 + βc, limited to 1.0, what punching-shear stress limit without shear reinforcement is obtained approximately?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The column aspect parameter is βc = 300/900 = 1/3. The shape factor is therefore ks = 0.5 + 1/3 = approximately 0.833, which is below the cap of 1.0. For M25 concrete, τc = 0.25√25 = 1.25 N/mm². The permitted punching shear stress is about 0.833 × 1.25 = 1.042 N/mm². Therefore Option C is correct.
వివరణ:
Question 20
ప్రశ్న 20
Where must development length of footing reinforcement be checked under IS 456?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
IS 456 identifies specific sections for checking development length in footings. The check is required at the same planes used for the critical bending-moment provisions. It is also required at other vertical planes where abrupt changes of section occur, which is important in stepped or otherwise varying footings. When reinforcement is curtailed, the separate anchorage provisions for curtailed bars must also be satisfied. Therefore Option B is correct.
వివరణ:
Question 21
ప్రశ్న 21
How is tensile reinforcement distributed in a two-way reinforced square footing under IS 456?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a two-way reinforced square footing, IS 456 gives a straightforward distribution rule. The reinforcement extending in each orthogonal direction is distributed uniformly across the full width of the footing. This differs from the special short-direction distribution rule applicable to a two-way rectangular footing. The actual amount in each direction must still provide the required flexural resistance and satisfy minimum reinforcement and spacing provisions. Therefore Option B is correct.
వివరణ:
Question 22
ప్రశ్న 22
A two-way rectangular footing is 3.0 m long and 2.0 m wide. What fraction of the total reinforcement in the short direction is to be placed uniformly in the central band under the IS 456 distribution rule?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a rectangular footing, β is the ratio of the long side to the short side. Here β = 3.0/2.0 = 1.5. The fraction of the total short-direction reinforcement assigned to the central band is 2/(β + 1). Hence the fraction is 2/2.5 = 0.80, while the remainder is distributed in the outer portions. Therefore Option C is correct.
వివరణ:
Question 23
ప్రశ్న 23
Under Limit State design, which expression correctly describes the concrete bearing stress permitted at the base of a column or pedestal when load spreads into a supporting footing?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
IS 456 permits enhancement of concrete bearing strength when the supporting area is larger than the loaded area. For Limit State design, the base value on the full loaded area is 0.45fck. This is multiplied by √(A1/A2), where A1 is the defined supporting area and A2 is the loaded area. The square-root enhancement factor is limited to a maximum value of 2. Therefore Option B is correct.
వివరణ:
Question 24
ప్రశ్న 24
An M25 column base bears on a footing for which the effective supporting-area ratio A1/A2 is 4.0. What maximum design bearing stress is permitted by the IS 456 load-transfer expression?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The square root of A1/A2 is √4 = 2.0. This equals the maximum permitted enhancement factor, so no further increase is allowed. The Limit State bearing stress is therefore 0.45 × 25 × 2.0. This evaluates to 22.50 N/mm². Therefore Option C is correct.
వివరణ:
Question 25
ప్రశ్న 25
A 400 mm × 400 mm column uses 20 mm longitudinal bars and transfers load to a footing through extended bars or dowels. Which minimum dowel/extended-reinforcement provision is consistent with IS 456?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
IS 456 requires extended longitudinal reinforcement or dowels of at least 0.5 percent of the cross-sectional area of the supported column or pedestal, with a minimum of four bars. For a 400 mm × 400 mm column, 0.5 percent of 160000 mm² is 800 mm². Where separate dowels are used, their diameter is not to exceed the diameter of the column bars by more than 3 mm. With 20 mm column bars, that upper comparison value is therefore 23 mm. Hence Option B is correct.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: A. To transfer column or wall actions safely to the supporting soil without exceeding acceptable soil pressure and while limiting differential settlement సమాధానం: A.
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Question 2 ప్రశ్న 2Answer: A. Net pressure is the gross contact pressure minus the pre-existing overburden pressure at foundation level సమాధానం: A.
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Question 3 ప్రశ్న 3Answer: B. 7.20 m² సమాధానం: B.
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Question 4 ప్రశ్న 4Answer: C. 250 kN/m² సమాధానం: C.
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Question 5 ప్రశ్న 5Answer: C. 1.10 m సమాధానం: C.
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Question 6 ప్రశ్న 6Answer: C. At the face of the column సమాధానం: C.
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Question 7 ప్రశ్న 7Answer: B. 121 kN·m/m సమాధానం: B.
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Question 8 ప్రశ్న 8Answer: B. 636 mm²/m సమాధానం: B.
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Question 9 ప్రశ్న 9Answer: C. 624 mm²/m సమాధానం: C.
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Question 10 ప్రశ్న 10Answer: C. 50 mm సమాధానం: C.
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Question 11 ప్రశ్న 11Answer: B. 150 mm and 300 mm సమాధానం: B.
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Question 12 ప్రశ్న 12Answer: A. At d for a footing on soil and at d/2 for a footing on piles సమాధానం: A.
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Question 13 ప్రశ్న 13Answer: C. 130 kN/m సమాధానం: C.
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Question 14 ప్రశ్న 14Answer: C. 0.289 N/mm² సమాధానం: C.
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Question 15 ప్రశ్న 15Answer: B. At a distance d/2 from the column periphery సమాధానం: B.
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Question 16 ప్రశ్న 16Answer: C. 3.40 m సమాధానం: C.
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Question 17 ప్రశ్న 17Answer: C. 0.76 N/mm² సమాధానం: C.
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Question 18 ప్రశ్న 18Answer: C. 1.25 N/mm² సమాధానం: C.
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Question 19 ప్రశ్న 19Answer: C. 1.042 N/mm² సమాధానం: C.
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Question 20 ప్రశ్న 20Answer: B. At the bending-moment critical planes and at other vertical planes where abrupt changes of section occur, with curtailment anchorage also checked where applicable సమాధానం: B.
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Question 21 ప్రశ్న 21Answer: B. Reinforcement in each direction is distributed uniformly across the full width of the footing సమాధానం: B.
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Question 22 ప్రశ్న 22Answer: C. 0.80 సమాధానం: C.
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Question 23 ప్రశ్న 23Answer: B. 0.45fck√(A1/A2), with the square-root factor not greater than 2 సమాధానం: B.
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Question 24 ప్రశ్న 24Answer: C. 22.50 N/mm² సమాధానం: C.
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Question 25 ప్రశ్న 25Answer: B. At least 800 mm² and at least four bars; if separate dowels are used, their diameter must not exceed 23 mm for the stated 20 mm column bars సమాధానం: B.