21. An R.C. square footing of side length 2 m and uniform effective depth 200 mm is provided for a 300 mm × 300 mm column. The line of action of the vertical compressive load passes through the centroid of the footing as well as of the column. If the magnitude of the load is 320 kN, the nominal transverse (one way) shear stress in the footing is

1. 1. 0.26 N/mm²

   
   
   

   2. 0.30 N/mm²

   
   
   

   3. 0.34 N/mm²

   
   
   

   4. 0.75 N/mm²

   
   
   

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1. View Hint View Answer Discuss in Forum

   For transverse shear, critical section is at a distance of 200 mm (d) from face for column.
   
   Uniform thrust due to applied load on the footing from soil, P₀
   

   P0 =	320 × 103	= 0.08 N/mm2
   	2000 × 2000

   
   Nominal transverse shear force on footing
   

   = P0 × B ×		1	(B - b) - d
   		2

   
   

   = 0.08 × 2000 ×		1	(2000 - 300) - 200		= 104000 N
   		2

   
   ∴ shear stress = 104000/Bd
   

   =	104000	= 0.26 N/mm2
   	2000 × 200

   Correct Option: A

   For transverse shear, critical section is at a distance of 200 mm (d) from face for column.
   
   Uniform thrust due to applied load on the footing from soil, P₀
   

   P0 =	320 × 103	= 0.08 N/mm2
   	2000 × 2000

   
   Nominal transverse shear force on footing
   

   = P0 × B ×		1	(B - b) - d
   		2

   
   

   = 0.08 × 2000 ×		1	(2000 - 300) - 200		= 104000 N
   		2

   
   ∴ shear stress = 104000/Bd
   

   =	104000	= 0.26 N/mm2
   	2000 × 200

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22. A simply supported prestressed concrete beam is 6 m long the 300 mm wide. Its gross depth is 600 mm. It is prestressed by horizontal cable tendons at a uniform eccentricity of 100 mm. The prestressing tensile force in the cable tendons is 1000 kN. Neglect the self weight of beam. The maximum normal compressive stress in the beam at transfer is

1. 1. Zero

   
   
   

   2. 5.55 N/mm²

   
   
   

   3. 11.11 N/mm²

   
   
   

   4. 15.68 N/mm²

   
   
   

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1. View Hint View Answer Discuss in Forum

   σmax =	P	+	Pe
   	A		Z

   
   

   Correct Option: C

   σmax =	P	+	Pe
   	A		Z

   
   

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23. IS: 1343 - 1980 limits the minimum characteristics strength of prestressed concrete for post tensioned works and pretension work as

1. 1. 25 MPa, 30 MPa respectively

   
   
   

   2. 25 MPa, 35 MPa respectively

   
   
   

   3. 30 MPa, 35 MPa respectively

   
   
   

   4. 30 MPa, 40 MPa respectively

   
   
   

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1. View Hint View Answer Discuss in Forum

   30 MPa, 40 MPa respectively

   Correct Option: D

   30 MPa, 40 MPa respectively

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24. The partial factor of safety for concrete as IS: 456-2000 is

1. 1. 1.50

   
   
   

   2. 1.15

   
   
   

   3. 0.87

   
   
   

   4. 0.446

   
   
   

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1. View Hint View Answer Discuss in Forum

   1.50

   Correct Option: A

   1.50

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25. A concrete beam of rectangular cross section of 200 mm × 400 mm is prestress with a force 400 kN at eccentricity 100 m. The maximum compressive stress in the concrete is

1. 1. 12.5 N/mm²

   
   
   

   2. 7.5 N/mm²

   
   
   

   3. 5.0 N/mm²

   
   
   

   4. 2.5 N/mm²

   
   
   

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1. View Hint View Answer Discuss in Forum

   σmin =	P	-	Pe
   	A		Z

   
   

   Correct Option: A

   σmin =	P	-	Pe
   	A		Z

   
   

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