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Question 1
ప్రశ్న 1
For structural design of a conventional RCC cantilever retaining wall, how is the stem primarily idealized?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The stem rises from the base slab and is restrained strongly at its lower end by the stem-base junction. Lateral earth, surcharge and water pressures act over its height and cause cantilever bending. The largest bending action normally occurs near the base of the stem. The structural design therefore treats a one-metre strip of stem as a vertical cantilever unless a different wall system is specifically present. Therefore Option B is correct.
వివరణ:
Question 2
ప్రశ్న 2
For the usual retained-earth loading direction on a cantilever retaining-wall stem, where is the principal vertical flexural reinforcement generally placed?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The lateral pressure from the retained soil pushes the stem toward the exposed side. The stem therefore bends as a cantilever fixed at its base. For this usual loading direction, the backfill face is the principal tension face, particularly near the bottom where the bending moment is largest. Main vertical reinforcement is consequently concentrated toward the backfill face, while secondary reinforcement is also required for detailing and crack control. Therefore Option C is correct.
వివరణ:
Question 3
ప్రశ్న 3
A 5.0 m high stem is subjected to a factored triangular lateral pressure varying from zero at the top to 36 kN/m² at the base. For a one-metre length of wall, what are the resultant lateral force and its bending moment about the stem base?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The resultant of a triangular pressure diagram is one-half of its base intensity multiplied by its height. Thus the force is 0.5 × 36 × 5 = 90 kN/m. A triangular pressure resultant acts at one-third of the height above the end having the maximum intensity. Its lever arm about the stem base is therefore 5/3 m. The bending moment is 90 × 5/3 = 150 kN·m/m, so Option D is correct.
వివరణ:
Question 4
ప్రశ్న 4
The same 5.0 m high stem is also subjected to a factored uniform lateral pressure of 8 kN/m² due to a specified surcharge effect. What lateral force and base moment are produced by this uniform pressure per metre length of wall?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A uniform lateral pressure of 8 kN/m² acting over a 5 m height gives a resultant force of 8 × 5 = 40 kN/m. The resultant of a uniform pressure distribution acts at the mid-height. Its lever arm about the base is therefore 2.5 m. The resulting bending moment is 40 × 2.5 = 100 kN·m/m. Therefore Option A is correct.
వివరణ:
Question 5
ప్రశ్న 5
A retaining-wall stem is subjected simultaneously to the factored pressure systems in the previous two questions. What are the total factored base shear and base bending moment?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The total horizontal force is obtained by adding the two lateral resultants. This gives 90 + 40 = 130 kN/m. The corresponding bending moments act in the same direction at the stem base. Hence the total base moment is 150 + 100 = 250 kN·m/m. Therefore Option A is correct.
వివరణ:
Question 6
ప్రశ్న 6
For the same 5.0 m stem, consider a section 2.0 m above its base. The triangular factored pressure varies linearly from zero at the wall top to 36 kN/m² at the base, and the uniform lateral pressure remains 8 kN/m². What bending moment acts at this section due to the pressures above it?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The height of retained wall above the section is 5 - 2 = 3 m. The triangular-pressure intensity at the section is 36 × 3/5 = 21.6 kN/m², so its resultant is 0.5 × 21.6 × 3 = 32.4 kN/m acting 1.0 m above the section. Its moment is therefore 32.4 kN·m/m. The uniform component gives 8 × 3 = 24 kN/m acting 1.5 m above the section, contributing 36 kN·m/m; hence the total is 68.4 kN·m/m and Option B is correct.
వివరణ:
Question 7
ప్రశ్న 7
An M25 retaining-wall stem strip 1000 mm wide has effective depth d = 450 mm at its base and must resist Mu = 250 kN·m/m using Fe500 reinforcement. Using the singly reinforced Limit State equations, what main tension-steel area is required approximately before separate minimum/detailing checks?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a singly reinforced section, force equilibrium gives xu = 0.87fyAst/(0.36fckb). The flexural resistance is Mu = 0.87fyAst(d - 0.42xu). Substituting b = 1000 mm, d = 450 mm, fck = 25 N/mm², fy = 500 N/mm² and Mu = 250 kN·m gives Ast of approximately 1361 mm²/m. The resulting neutral-axis depth remains within the limiting range for Fe500 steel. Therefore Option C is correct.
వివరణ:
Question 8
ప్రశ్న 8
At the base of the stem in the previous loading example, the factored horizontal shear is 130 kN/m. If b = 1000 mm and d = 450 mm, what nominal shear stress V/(bd) is obtained?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The nominal shear stress is obtained from τv = V/(bd). The shear force is 130000 N for a one-metre strip. The resisting area term is 1000 × 450 = 450000 mm². Thus τv = 130000/450000 = approximately 0.289 N/mm². Therefore Option C is correct.
వివరణ:
Question 9
ప్రశ్న 9
Why is the stem of a cantilever retaining wall often made thicker near its base and thinner toward the top?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Lateral pressure ordinarily accumulates with depth, and the stem behaves as a cantilever. Consequently both shear and bending moment are substantially greater near the fixed base than near the free top. A thicker lower stem provides the effective depth needed for these larger actions. Thickness can often be reduced toward the top where the structural demand is smaller, provided strength, cover, reinforcement and constructability requirements remain satisfied. Therefore Option B is correct.
వివరణ:
Question 10
ప్రశ్న 10
What is the principal function of horizontal reinforcement provided in the stem in addition to the main vertical flexural reinforcement?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The dominant cantilever bending of the stem normally requires vertical main reinforcement. Reinforcement is also provided in the horizontal direction even though it is not the primary steel for the usual vertical cantilever action. This secondary reinforcement helps distribute cracking and control effects associated with shrinkage, temperature and local restraint. It also assists in maintaining an effective reinforcement cage. Therefore Option C is correct.
వివరణ:
Question 11
ప్రశ్న 11
A 1.60 m heel projection is subjected to factored downward actions totalling 80 kN/m² and a factored upward soil reaction of 30 kN/m². Treating a one-metre strip of heel as a cantilever, what are the net loading and bending-moment magnitude at the stem face?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The heel is subjected to both downward and upward actions, so the net structural load must first be established. The stated downward pressure is 80 kN/m² and the upward reaction is 30 kN/m², giving a net downward pressure of 50 kN/m². For a one-metre strip, this is a line load of 50 kN/m. The fixed-end cantilever moment is 50 × 1.60²/2 = 64 kN·m/m. Therefore Option A is correct.
వివరణ:
Question 12
ప్రశ్న 12
For the net downward heel loading described in the previous question, where is the principal flexural tension reinforcement required near the stem?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The heel projects behind the stem and behaves as a cantilever fixed at the stem. When its specified net load acts downward, the heel bends in the conventional downward-loaded cantilever sense. This places the upper portion near the stem in tension. Main flexural reinforcement is therefore required near the top face of the heel for this loading direction. Therefore Option A is correct.
వివరణ:
Question 13
ప్రశ్న 13
A one-metre heel strip of M25 concrete with Fe500 steel has effective depth d = 350 mm and factored design moment Mu = 90 kN·m at the stem face. What flexural tension-steel area is required approximately from the singly reinforced strength equations, before separate minimum/detailing checks?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The reinforced-concrete flexural calculation uses the same Limit State equilibrium equations as an ordinary singly reinforced cantilever strip. Taking b = 1000 mm, d = 350 mm, fck = 25 N/mm², fy = 500 N/mm² and Mu = 90 kN·m gives an Ast of approximately 613 mm²/m. This value represents the strength requirement from the stated moment alone. Minimum reinforcement, spacing, cover and anchorage still have to be checked separately. Therefore Option B is correct.
వివరణ:
Question 14
ప్రశ్న 14
A heel projection 1.50 m long carries a net factored downward pressure of 80 kN/m². For a one-metre strip having effective depth 350 mm, what are the shear force at the stem face and the corresponding nominal shear stress?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a cantilever carrying a uniform load, the shear force at the fixed face equals the total load on the projection. The one-metre strip therefore carries V = 80 × 1.50 = 120 kN. With b = 1000 mm and d = 350 mm, the nominal shear stress is 120000/(1000 × 350). This gives approximately 0.343 N/mm². Therefore Option B is correct.
వివరణ:
Question 15
ప్రశ్న 15
A 1.10 m toe projection has a factored upward soil reaction of 180 kN/m² and specified factored downward actions of 20 kN/m². What is the net loading and cantilever bending-moment magnitude at the stem face per metre width?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The net toe loading is obtained by subtracting the specified downward actions from the upward soil reaction. Thus the net pressure is 180 - 20 = 160 kN/m² upward. For a one-metre strip this becomes 160 kN/m. The fixed-face moment magnitude is 160 × 1.10²/2 = 96.8 kN·m/m. Therefore Option A is correct.
వివరణ:
Question 16
ప్రశ్న 16
For the usual toe condition in which the net design load acts upward, where is the principal flexural tension reinforcement required near the stem?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The toe acts as a horizontal cantilever projecting from the stem toward the exposed side of the wall. A net upward pressure bends this projection upward relative to the fixed stem junction. The resulting cantilever bending places the lower face in principal tension near the stem. Main toe reinforcement is therefore generally located near the bottom face for this specified load direction. Therefore Option B is correct.
వివరణ:
Question 17
ప్రశ్న 17
A one-metre toe strip of M25 concrete and Fe500 steel has effective depth d = 300 mm and must resist a factored moment of 83.75 kN·m. What tensile reinforcement area is required approximately from the singly reinforced flexural strength equations?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For the one-metre strip, b = 1000 mm and d = 300 mm. Applying the singly reinforced Limit State equations with fck = 25 N/mm² and fy = 500 N/mm² gives the steel area required to resist the stated 83.75 kN·m moment. The calculated value is approximately 672 mm²/m. This is a flexural strength result and must still satisfy the applicable minimum-steel and detailing requirements. Therefore Option C is correct.
వివరణ:
Question 18
ప్రశ్న 18
A 1.0 m toe projection carries a net factored upward load of 167.5 kN/m². For a one-metre strip with effective depth 300 mm, what nominal shear stress occurs at the stem face?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The shear force at the fixed stem face equals the resultant net load on the toe projection. For a one-metre strip and one-metre projection, V = 167.5 kN. The nominal shear stress is therefore 167500/(1000 × 300). This evaluates to approximately 0.558 N/mm². Therefore Option C is correct.
వివరణ:
Question 19
ప్రశ్న 19
In the heel and toe slabs of a long straight cantilever retaining wall, which reinforcement-direction statement is generally correct for the principal cantilever action?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Heel and toe projections cantilever transversely from the stem. Their principal bending span therefore runs from the stem toward the free outer edge. Main flexural reinforcement follows this span direction and is consequently placed perpendicular to the longitudinal direction of the wall. Secondary or distribution reinforcement is generally provided approximately parallel to the wall length. Therefore Option B is correct.
వివరణ:
Question 20
ప్రశ్న 20
Why must the main vertical stem reinforcement be adequately anchored into the base slab?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The largest cantilever bending moment in the stem normally develops near its base. The main vertical steel therefore carries a substantial tensile force at or near the stem-base junction. That reinforcement must be continued, bent or otherwise anchored so that its design stress can be safely developed within the connected concrete. Merely terminating the bars at the theoretical face of the base would not provide the required force transfer. Therefore Option B is correct.
వివరణ:
Question 21
ప్రశ్న 21
For the ordinary cantilever idealization of the heel and toe slabs, where is the critical section for the maximum flexural moment produced by their net distributed loads?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Both heel and toe projections are structurally idealized as cantilevers connected to the stem region. The bending moment of a cantilever under distributed load increases from zero at the free end toward the fixed end. Its maximum magnitude consequently occurs at the support. For retaining-wall base projections, this critical structural region is at the face of the stem under the stated cantilever idealization. Therefore Option C is correct.
వివరణ:
Question 22
ప్రశ్న 22
Which statement correctly describes the structural significance of drainage behind an RCC retaining wall?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Water can produce substantial lateral pressure behind a retaining wall. Proper drainage systems such as drainage layers, filters and weep arrangements are intended to prevent excessive buildup of this pressure. Structural design should not simply assume zero water pressure when drainage performance or groundwater conditions do not justify that assumption. Where water can accumulate, its hydrostatic action has to be included together with the other specified lateral loads. Therefore Option B is correct.
వివరణ:
Question 23
ప్రశ్న 23
A 4.0 m depth of water behind a stem produces a triangular hydrostatic pressure distribution with a specified maximum intensity of 40 kN/m² at the base. What additional structural bending moment does this water pressure produce at the base per metre length?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The hydrostatic pressure diagram is triangular over the stated 4 m height. Its resultant force is 0.5 × 40 × 4 = 80 kN/m. The centroid of this triangular pressure acts at H/3 above the base, giving a lever arm of 4/3 m. The corresponding base moment is 80 × 4/3 = approximately 106.7 kN·m/m. Therefore Option C is correct.
వివరణ:
Question 24
ప్రశ్న 24
Which detailing principle is most appropriate at the monolithic stem-base junction of a cantilever retaining wall?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The stem-base junction is the fixed region of the cantilever wall and transfers significant bending moment and shear. Reinforcement crossing or anchoring into this region must therefore be detailed to develop the forces assumed in structural analysis. The connection is intended to act monolithically rather than as an unreinforced hinge. Concrete cover, bar spacing, development length and construction practicality must all be respected. Therefore Option B is correct.
వివరణ:
Question 25
ప్రశ్న 25
When the calculated flexural requirement in a retaining-wall stem decreases toward the top, which reinforcement-detailing approach is appropriate?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The bending demand in a cantilever stem decreases markedly toward its free end. It can therefore be economical to reduce the amount of main reinforcement in stages. However, reinforcement cannot simply terminate at the theoretical point where it first becomes unnecessary by flexural calculation. Anchorage, development, minimum reinforcement, spacing and crack-control requirements must remain satisfied throughout the stem. Therefore Option B is correct.
వివరణ:
Question 26
ప్రశ్న 26
Match the principal tension face for the usual specified loading of the three main cantilever retaining-wall components: 1. Stem under retained-earth pressure, 2. Heel under net downward loading, 3. Toe under net upward loading. Which combination is correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The stem bends under lateral retained-earth pressure and develops its principal vertical tension near the backfill face for the usual loading direction. A heel subjected to net downward loading behaves as a downward-loaded cantilever and develops top-face tension near the stem. A toe subjected to net upward soil reaction develops the opposite curvature and therefore bottom-face tension near the stem. These tension-face locations govern the placement of the corresponding principal flexural reinforcement. Therefore Option C is correct.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: B. As a vertical cantilever fixed into the base slab సమాధానం: B.
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Question 2 ప్రశ్న 2Answer: C. Near the backfill face where the principal flexural tension develops సమాధానం: C.
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Question 3 ప్రశ్న 3Answer: D. 90 kN/m and 150 kN·m/m సమాధానం: D.
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Question 4 ప్రశ్న 4Answer: A. 40 kN/m and 100 kN·m/m సమాధానం: A.
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Question 5 ప్రశ్న 5Answer: A. 130 kN/m and 250 kN·m/m సమాధానం: A.
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Question 6 ప్రశ్న 6Answer: B. 68.4 kN·m/m సమాధానం: B.
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Question 7 ప్రశ్న 7Answer: C. 1361 mm²/m సమాధానం: C.
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Question 8 ప్రశ్న 8Answer: C. 0.289 N/mm² సమాధానం: C.
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Question 9 ప్రశ్న 9Answer: B. Because bending moment and shear generally increase toward the fixed base, allowing a structurally efficient taper subject to detailing requirements సమాధానం: B.
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Question 10 ప్రశ్న 10Answer: C. To serve as secondary/distribution reinforcement and assist crack control from shrinkage and temperature effects సమాధానం: C.
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Question 11 ప్రశ్న 11Answer: A. 50 kN/m downward and 64 kN·m/m సమాధానం: A.
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Question 12 ప్రశ్న 12Answer: A. Near the top face of the heel సమాధానం: A.
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Question 13 ప్రశ్న 13Answer: B. 613 mm²/m సమాధానం: B.
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Question 14 ప్రశ్న 14Answer: B. 120 kN/m and 0.343 N/mm² సమాధానం: B.
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Question 15 ప్రశ్న 15Answer: A. 160 kN/m upward and 96.8 kN·m/m సమాధానం: A.
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Question 16 ప్రశ్న 16Answer: B. Near the bottom face సమాధానం: B.
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Question 17 ప్రశ్న 17Answer: C. 672 mm²/m సమాధానం: C.
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Question 18 ప్రశ్న 18Answer: C. 0.558 N/mm² సమాధానం: C.
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Question 19 ప్రశ్న 19Answer: B. Main flexural bars run from the stem toward the heel or toe, while secondary/distribution bars run approximately parallel to the wall length సమాధానం: B.
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Question 20 ప్రశ్న 20Answer: B. Because the critical stem bending moment occurs near the base and the tensile force in the vertical bars must be developed through the stem-base connection సమాధానం: B.
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Question 21 ప్రశ్న 21Answer: C. At the face of the stem where the cantilever is fixed సమాధానం: C.
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Question 22 ప్రశ్న 22Answer: B. Reliable drainage can reduce hydrostatic pressure, but if water accumulation cannot be reliably excluded the corresponding water pressure must be included in the wall actions సమాధానం: B.
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Question 23 ప్రశ్న 23Answer: C. 106.7 kN·m/m సమాధానం: C.
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Question 24 ప్రశ్న 24Answer: B. Provide continuity and adequate development/anchorage of the reinforcement required to transfer bending and shear through the junction సమాధానం: B.
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Question 25 ప్రశ్న 25Answer: B. Reinforcement may be reduced progressively only while maintaining required minimum steel, spacing, anchorage and development beyond theoretical cutoff locations సమాధానం: B.
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Question 26 ప్రశ్న 26Answer: C. 1-Backfill face, 2-Top face, 3-Bottom face సమాధానం: C.