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Question 1
ప్రశ్న 1
Which statement best defines the shear centre of a beam cross-section?
Explanation:
The shear centre is associated with transverse loading of a beam rather than with pure axial loading. If a transverse resultant passes through the shear centre, the load does not create a twisting moment about the longitudinal axis of the member. The beam may still bend and develop substantial shear stresses. For open thin-walled sections, the shear centre may lie outside the material of the cross-section. Therefore Option B gives the correct definition.
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Question 2
ప్రశ్న 2
For a homogeneous thin-walled open section, which statement correctly distinguishes the centroid from the shear centre?
Explanation:
The centroid is a geometric area property obtained from first moments of area. For a homogeneous member, the centre of gravity coincides with the centroid if density is uniform. The shear centre is defined from the moment produced by the internal shear-flow distribution under transverse shear. In singly symmetric or unsymmetric open sections, its position can differ substantially from the centroid. Therefore Option C is correct.
వివరణ:
Question 3
ప్రశ్న 3
A thin-walled open section possesses exactly one axis of symmetry. What can be stated about its shear centre?
Explanation:
Symmetry requires the shear-centre position to be compatible with the reflected geometry of the cross-section. If the shear centre were away from the single symmetry axis, reflection would imply a second different shear-centre location, which is not possible for the same section. The shear centre must therefore lie on the axis of symmetry. Its exact coordinate along that axis must still be obtained from moment equilibrium or an equivalent shear-flow calculation. Hence Option A is correct.
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Question 4
ప్రశ్న 4
A homogeneous cross-section has two perpendicular axes of symmetry. Where is its shear centre located under the usual elementary beam assumptions?
Explanation:
A section with two symmetry axes requires the shear centre to lie on each symmetry axis. The only point satisfying both requirements is their intersection. For a homogeneous doubly symmetric section, that intersection is also the centroid. Thus common doubly symmetric I-sections and rectangular sections have coincident centroid and shear centre under the elementary theory. Therefore Option D is correct.
వివరణ:
Question 5
ప్రశ్న 5
Consider a conventional thin-walled channel section with a vertical web and equal horizontal flanges projecting to the right, so that its horizontal centroidal axis is an axis of symmetry. Where is the shear centre for vertical transverse shear?
Explanation:
The channel has one horizontal axis of symmetry, so the shear centre must lie on that axis. Shear flow in the top and bottom flanges produces equal and opposite horizontal resultants separated vertically by the flange spacing. These flange forces form a couple about the web. To prevent twist, the applied vertical shear must create an opposing moment, placing its line of action outside the web on the side away from the flanges. Therefore Option B is correct.
వివరణ:
Question 6
ప్రశ్న 6
An ideal thin-walled angle consists of two straight narrow legs meeting at right angles, with corner radius neglected. Where is its shear centre in the standard thin-wall idealization?
Explanation:
In an ideal thin-walled angle, shear flow in each leg acts tangentially along that leg. The resultant shear forces associated with the two legs therefore have lines of action passing through the intersection of the leg centre-lines. A transverse resultant passing through that intersection produces no additional twisting moment from eccentricity. The centroid of an angle generally lies away from this junction. Hence Option C is correct.
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Question 7
ప్రశ్న 7
An ideal thin-walled T-section consists of a horizontal flange and a vertical stem, both represented by narrow rectangles, and is symmetric about the vertical stem centre-line. Where is its shear centre in this idealization?
Explanation:
The vertical centre-line of the stem is an axis of symmetry, so the shear centre must lie on that line. For the idealized T made from two narrow intersecting rectangles, the internal shear-resultant lines pass through the flange-stem centre-line junction. The resulting shear centre is therefore located at that junction. The centroid generally lies below the flange-stem junction and need not coincide with the shear centre. Therefore Option A is correct.
వివరణ:
Question 8
ప్రశ్న 8
For a thin-walled open beam under a transverse shear force V acting along a principal bending direction, which relation correctly connects shear flow q, first moment of area Q, second moment of area I and wall thickness t?
Explanation:
The ordinary beam-shear relation is τ = VQ/(It) for a local wall thickness t. Multiplying shear stress by the local thickness gives the shear flow q. Therefore q = τt = VQ/I. Conversely, once shear flow is known, the local shear stress is τ = q/t. Hence Option D is correct.
వివరణ:
Question 9
ప్రశ్న 9
What are the dimensions of shear flow q in a thin-walled beam?
Explanation:
Shear flow is defined as shear force transmitted per unit length along the wall of a thin-walled section. It is related to shear stress by q = τt. Since shear stress has dimensions of force per unit area and thickness has dimensions of length, their product has dimensions of force per unit length. Typical engineering units are N/mm or kN/m. Therefore Option B is correct.
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Question 10
ప్రశ్న 10
For an open thin-walled section with no externally applied longitudinal edge traction, what is the shear flow at a free edge?
Explanation:
At a free edge of an open thin-walled section, there is no adjacent wall beyond the edge through which longitudinal shear can continue. Under the usual beam-shear idealization and without an applied edge traction, the shear flow therefore starts or ends at zero. As one proceeds along the wall, the accumulated first moment of area changes and the shear flow develops accordingly. This zero-flow free-edge condition is important when constructing shear-flow distributions for channels and other open sections. Therefore Option A is correct.
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Question 11
ప్రశ్న 11
A transverse shear force V acts at an eccentricity e from the shear centre of a beam section. What is the magnitude of the additional twisting moment about the longitudinal axis?
Explanation:
The shear centre is the reference point through which transverse loading causes no torsional moment from load eccentricity. If the force is displaced from that point by a perpendicular distance e, it has a moment arm e. The twisting moment is therefore the force multiplied by this eccentricity. Its magnitude is T = Ve, with the sign determined by the direction of the force and offset. Hence Option C is correct.
వివరణ:
Question 12
ప్రశ్న 12
A transverse force passes exactly through the shear centre of a thin-walled open beam section. Which statement is correct?
Explanation:
Passing the load through the shear centre eliminates the torsional effect associated with eccentric transverse loading. It does not eliminate the transverse shear force itself. The member can consequently develop bending moments, normal bending stresses and shear stresses. The shear centre is not a point of zero stress and it need not coincide with the centroid. Therefore Option D is correct.
వివరణ:
Question 13
ప్రశ్న 13
A thin-walled channel has flange length b measured from the web centre-line, distance h between flange centre-lines, flange thickness tf and web thickness tw. Using the usual thin-wall approximation, which expression gives the distance e of the shear centre from the web centre-line on the side opposite the flanges?
Explanation:
For a channel, the horizontal resultant in each flange is obtained by integrating the flange shear flow. The two equal and opposite flange resultants form a couple separated approximately by the flange-centre-line distance h. Moment equilibrium between this couple and the external shear force locates the shear centre. Using the usual thin-wall approximation for the second moment of area gives e = 3b²tf/(htw + 6btf). Therefore Option B is correct.
వివరణ:
Question 14
ప్రశ్న 14
A uniform-thickness thin-walled channel has flanges of length b = 100 mm measured from the web centre-line and a distance h = 150 mm between flange centre-lines. Using e = 3b²/(h + 6b), what is the shear-centre distance from the web centre-line?
Explanation:
For equal web and flange thickness, the standard channel expression reduces to e = 3b²/(h + 6b). Substituting b = 100 mm and h = 150 mm gives e = 3(100²)/(150 + 600). The numerator is 30000 mm² and the denominator is 750 mm. Thus e = 40 mm on the side of the web opposite the flanges, so Option C is correct.
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Question 15
ప్రశ్న 15
A thin-walled channel has flange length b = 100 mm from the web centre-line, flange-centre-line spacing h = 200 mm, flange thickness tf = 5 mm and web thickness tw = 10 mm. Using e = 3b²tf/(htw + 6btf), what is e?
Explanation:
The numerator is 3 × 100² × 5 = 150000 mm³. The denominator is 200 × 10 + 6 × 100 × 5. This gives 2000 + 3000 = 5000 mm². Hence e = 150000/5000 = 30 mm. The shear centre is located 30 mm from the web centre-line on the side opposite the flanges, so Option A is correct.
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Question 16
ప్రశ్న 16
A thin-walled channel has flange length b = 130 mm measured to the web centre-line, flange-centre-line spacing h = 250 mm, flange thickness tf = 3 mm and second moment of area about the horizontal symmetry axis I = 1.6096 × 10^7 mm^4. Using e = h²tfb²/(4I), what is the shear-centre distance from the web centre-line approximately?
Explanation:
The specified expression uses the flange force couple directly through the known second moment of area. Substitution gives e = 250² × 3 × 130² divided by 4 × 1.6096 × 10^7. Evaluating the numerator and denominator gives e approximately equal to 49.22 mm. The location is on the horizontal symmetry axis and on the side of the web opposite the flanges. Therefore Option D is correct.
వివరణ:
Question 17
ప్రశ్న 17
A uniform thin-walled channel has b = 100 mm, h = 150 mm, thickness t = 4 mm and I = 5.625 × 10^6 mm^4 about its horizontal symmetry axis. A vertical shear V = 20 kN acts through the shear centre. Using F = Vthb²/(4I) for the horizontal resultant in each flange, which pair is correct?
Explanation:
Substitution into the flange-resultant expression gives F = 20000 × 4 × 150 × 100² divided by 4 × 5.625 × 10^6. This evaluates to approximately 5333 N, or 5.333 kN, for each flange. The two flange resultants form a couple Fh. Equating this couple to Ve gives e = Fh/V = 5.333 × 150/20 = 40 mm when consistent units are used. Therefore Option B is correct.
వివరణ:
Question 18
ప్రశ్న 18
For the uniform channel in the previous question, the thin-wall centroid lies 28.57 mm from the web centre-line toward the flanges, while the shear centre lies 40 mm from the web centre-line on the opposite side. If a vertical shear force of 20 kN acts through the centroid, what twisting moment about the shear centre is produced approximately?
Explanation:
The centroid and shear centre are on opposite sides of the web centre-line in this channel. Their separation is therefore 28.57 + 40 = 68.57 mm. A load through the centroid is consequently eccentric by 68.57 mm from the shear centre. The twisting moment is 20 kN × 0.06857 m = approximately 1.371 kN·m. Hence Option C is correct.
వివరణ:
Question 19
ప్రశ్న 19
A uniform thin-walled channel has b = 80 mm, h = 240 mm, thickness t = 6 mm and I = 20.736 × 10^6 mm^4 about its horizontal symmetry axis. Under a vertical shear V = 30 kN, what are the flange shear flow and shear stress at the flange-web junction according to q = VQ/I?
Explanation:
At the flange-web junction, the first moment for the complete flange is Q = b t (h/2). The shear flow is therefore q = Vbth/(2I). Substitution gives q = 30000 × 80 × 6 × 240 divided by 2 × 20.736 × 10^6, which is 83.33 N/mm. The corresponding shear stress is τ = q/t = 83.33/6 = 13.89 N/mm². Therefore Option A is correct.
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Question 20
ప్రశ్న 20
A transverse force acts at a fixed eccentricity of 25 mm from the shear centre of a homogeneous beam section. If the force magnitude is doubled without changing the section or load line, which statement is correct?
Explanation:
For a homogeneous section under the assumptions of elementary elastic beam theory, the shear-centre position is a property of the cross-sectional geometry. It does not depend on the magnitude of the applied transverse shear force. The eccentricity is also unchanged because the load line is stated to remain fixed. Since the twisting moment is Ve, doubling V doubles the twisting moment. Therefore Option D is correct.
వివరణ:
Question 21
ప్రశ్న 21
Which statement about the shear centre of a homogeneous thin-walled section is most accurate?
Explanation:
The shear centre is determined by requiring the resultant internal shear stresses to have no unbalanced torsional effect about the line of application of transverse shear. Since the shear-flow field scales linearly with the applied force, that force cancels from the equation used to locate the shear centre. For a homogeneous isotropic section, its location is therefore governed primarily by the cross-sectional geometry. Changes in wall proportions can move the shear centre even when the material remains unchanged. Hence Option B is correct.
వివరణ:
Question 22
ప్రశ్న 22
For a general thin-walled open section having no axis of symmetry, which statement is correct?
Explanation:
An axis of symmetry provides a useful constraint on the possible shear-centre location. Without such symmetry, there is no corresponding geometric requirement forcing the shear centre onto a centroidal axis. Its coordinates must generally be obtained from the complete shear-flow distribution and moment equilibrium. The resulting point can lie within or outside the material boundaries. Therefore Option C is correct.
వివరణ:
Question 23
ప్రశ్న 23
The internal shear flows in a thin-walled open section produce a resultant couple of magnitude 0.90 kN·m about a chosen reference point. A transverse shear force of 30 kN is to be positioned so that its moment balances this couple and no twist occurs. What eccentricity magnitude is required?
Explanation:
For no twist, the external moment of the transverse force must balance the moment produced by the internal shear-flow resultants. In magnitude, the equilibrium condition is Ve = 0.90 kN·m. Thus e = 0.90/30 m. This equals 0.03 m, or 30 mm. Therefore Option A is correct.
వివరణ:
Question 24
ప్రశ్న 24
Consider the following statements about shear centre:
1. If a cross-section has one axis of symmetry, its shear centre lies on that axis.
2. If a homogeneous cross-section has two axes of symmetry, its shear centre coincides with their intersection and hence with the centroid.
3. The shear centre of a conventional channel necessarily coincides with its centroid.
4. A transverse load through the centroid of a channel can cause twisting if the centroid and shear centre do not coincide.
Which statements are correct?
1. If a cross-section has one axis of symmetry, its shear centre lies on that axis.
2. If a homogeneous cross-section has two axes of symmetry, its shear centre coincides with their intersection and hence with the centroid.
3. The shear centre of a conventional channel necessarily coincides with its centroid.
4. A transverse load through the centroid of a channel can cause twisting if the centroid and shear centre do not coincide.
Which statements are correct?
Explanation:
Statement 1 is correct because symmetry constrains the shear centre to the symmetry axis. Statement 2 is correct because two symmetry axes require the shear centre to lie at their intersection, which is also the centroid for the homogeneous section described. Statement 3 is incorrect because a conventional open channel usually has its shear centre outside the section and away from its centroid. Statement 4 is correct because a load acting through the centroid then has a non-zero eccentricity from the shear centre. Therefore Statements 1, 2 and 4 are correct and Option D is the unique answer.
వివరణ:
Question 25
ప్రశ్న 25
Match each shear-centre quantity with its correct relationship or interpretation:
1. Shear flow in a thin wall
2. Local shear stress from known shear flow
3. Twisting moment from a transverse force eccentric to the shear centre
4. Uniform-thickness channel shear-centre distance from the web centre-line, with flange length b and flange-centre-line spacing h
P. q/t
Q. 3b²/(h + 6b)
R. VQ/I
S. Ve
Which matching is correct?
1. Shear flow in a thin wall
2. Local shear stress from known shear flow
3. Twisting moment from a transverse force eccentric to the shear centre
4. Uniform-thickness channel shear-centre distance from the web centre-line, with flange length b and flange-centre-line spacing h
P. q/t
Q. 3b²/(h + 6b)
R. VQ/I
S. Ve
Which matching is correct?
Explanation:
Shear flow is q = VQ/I, so item 1 matches R. Local shear stress follows from τ = q/t, so item 2 matches P. A transverse force acting at eccentricity e from the shear centre creates twisting moment Ve, so item 3 matches S. For the stated uniform thin-walled channel approximation, the shear-centre distance is 3b²/(h + 6b), so item 4 matches Q. Therefore Option B gives the correct complete matching.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: B. It is the point through which the resultant transverse shear force must act so that bending occurs without twisting of the section. సమాధానం: B.
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Question 2 ప్రశ్న 2Answer: C. The centroid is determined from area distribution, whereas the shear centre is the point for transverse loading without twist and the two need not coincide. సమాధానం: C.
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Question 3 ప్రశ్న 3Answer: A. It must lie somewhere on that axis of symmetry. సమాధానం: A.
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Question 4 ప్రశ్న 4Answer: D. At the intersection of the two symmetry axes, coinciding with the centroid సమాధానం: D.
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Question 5 ప్రశ్న 5Answer: B. On the horizontal symmetry axis outside the section, on the side of the web opposite to the flanges సమాధానం: B.
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Question 6 ప్రశ్న 6Answer: C. At the intersection of the centre-lines of the two legs సమాధానం: C.
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Question 7 ప్రశ్న 7Answer: A. At the intersection of the flange and stem centre-lines సమాధానం: A.
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Question 8 ప్రశ్న 8Answer: D. q = VQ/I and τ = q/t సమాధానం: D.
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Question 9 ప్రశ్న 9Answer: B. Force per unit length సమాధానం: B.
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Question 10 ప్రశ్న 10Answer: A. It is zero at the free edge. సమాధానం: A.
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Question 11 ప్రశ్న 11Answer: C. Ve సమాధానం: C.
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Question 12 ప్రశ్న 12Answer: D. The load can produce bending and shear deformation, but it produces no twisting moment due to transverse-load eccentricity. సమాధానం: D.
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Question 13 ప్రశ్న 13Answer: B. e = 3b²tf/(htw + 6btf) సమాధానం: B.
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Question 14 ప్రశ్న 14Answer: C. 40 mm సమాధానం: C.
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Question 15 ప్రశ్న 15Answer: A. 30 mm సమాధానం: A.
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Question 16 ప్రశ్న 16Answer: D. 49.2 mm సమాధానం: D.
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Question 17 ప్రశ్న 17Answer: B. F = 5.333 kN in each flange and e = 40 mm సమాధానం: B.
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Question 18 ప్రశ్న 18Answer: C. 1.371 kN·m సమాధానం: C.
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Question 19 ప్రశ్న 19Answer: A. q = 83.33 N/mm and τ = 13.89 MPa సమాధానం: A.
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Question 20 ప్రశ్న 20Answer: D. The shear-centre position is unchanged, while the twisting moment doubles. సమాధానం: D.
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Question 21 ప్రశ్న 21Answer: B. Its position is primarily a cross-sectional geometric property and is independent of the applied load magnitude in linear elastic analysis. సమాధానం: B.
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Question 22 ప్రశ్న 22Answer: C. The shear centre need not lie on a centroidal axis and may lie either inside or outside the physical section. సమాధానం: C.
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Question 23 ప్రశ్న 23Answer: A. 30 mm సమాధానం: A.
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Question 24 ప్రశ్న 24Answer: D. 1, 2 and 4 only సమాధానం: D.
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Question 25 ప్రశ్న 25Answer: B. 1-R, 2-P, 3-S, 4-Q సమాధానం: B.
