7/30/2019 r5220103 Strength of Materials II

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Code No: R5220103 R5II B.Tech II Semester(R05) Supplementary Examinations, December 2010

STRENGTH OF MATERIALS-II(Civil Engineering)

Time: 3 hours Max Marks: 80Answer any FIVE Questions

All Questions carry equal marks

1. (a) Briefly explain the max. principal stress theory.

(b) A certain type of steel has proportionality limit of 270N/mm2 (tensile), 60N/mm2 (tensile) and30N/mm2 (compressive). Find the factor of safety according to max. principal stress theory.[6+10]

2. (a) What are springs and where they are used?

(b) How many types of springs are there? Explain the behaviour of each type.

(c) Give examples of the use of various types of springs? [6+6+4]

3. An R.S.Tee-section, 150mm wide 75mm deep, thickness of flange 9mm, thickness of web 8.4mm, isused as a strut, 3 metre 4 long, ends hinged.Calculate the safe axial load by Rankines formula, usinga factor of safety of 3. Rankines constants, f c = 315N/mm2; a = 1/ 7500. [16]

4. A short vertical pillar has a section of uniform thickness in the form of a hollow square of side 120 mmexternally and 80 mm internally. A vertical load of 210 KN is applied at a distance of 60 mm fromthe central axis of the pillar and on one of the diagonals of the square. What is the maximum stresson the cross-section? [16]

5. A cylindrical chimney shaft of a hollow circular section, 2.50 metres external diameter, 1 metre internaldiameter, is 30 metres high. If the horizontal intensity of wind pressure varies as X2/3 where X is thevertical height above the ground, calculate the overturning moment at the base due to the force ofwind pressure, taking the coefficient of wind-resistance as 0.6. Given that the horizontal intensity ofwind pressure at a height of 20 metres is 1KN/m2. If the weight of masonry is 22.5KN/m3, calculatethe extreme intensities of stress at the base. [16]

6. A simply-supported beam of T-section (100 150 20mm) carries a load P at center of 2.5m span.The load line is inclined at 30 to the vertical and passes through c.g If the max. Compressive stressis not to exceed 75N/mm2, and the max tensile stress is not to exceed 35N/mm2, find the max loadP which the bean can carry. [16]

7. (a) Where do you use beams curved in plan?

(b) A circular beam is loaded uniformly and supported an symmetrically placed Columns. If W isthe load per unit length, R, the radius, derive expressions for S.F B.M and tossional moment ata point P, at an angle from one support.

[4+12]

8. A uniformly loaded circular beam is supported on equally placed columns. Derive expressions formax.values of S.F, B.M. and torsional moment. Obtain salient values in the case of 6 supports. [16]

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