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Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY Diploma Engineering - SEMESTERIII EXAMINATION SUMMER 2014

Subject Code: 3330604 Date: 19-06-2014

Subject Name: Structural Mechanics

Time: 10:30 am - 01:00 pm Total Marks: 70 Instructions:

1. Attempt all questions. 2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks. 4. Each question carry equal marks (14 marks) 5. Use of scientific calculator is allowed.

Q.1 (a) 1. Explain difference between linear strain and lateral strain.

2. Define : Stress, Modulus of Elasticity, Poissons Ratio, Bulk Modulus.

03

04

(b) A mild steel bar 1.5 m long and 20mm in diameter is subjected to an axial

tensile force of 100 kN. Find stress, strain, change in length and final length.

Take E = 2 x 105 N/mm

2.

07

Q.2 (a) Explain parallel axis and perpendicular axis Theorem. 07

(b) Find Moment of Inertia about XX and YY axis of L section 100 x75x10 mm keeping its longer leg vertical

07

OR

(b) A circular R. C. C. column of 230 mm diameter is reinforced with 6 steel bars

of 20 mm diameter. The column is carrying a load of 750 kN. Find the

stresses in concrete and steel bar. Take Modular ratio = Es/Ec = 15

07

Q.3 (a) Draw shear force and bending moment diagram for the beam shown in Fig.1

Find maximum bending moment also. 07

(b) Draw shear force and bending moment diagram for the beam shown in Fig.2 07

OR

Q.3 (a) Draw shear force and bending moment diagram for the beam shown in Fig.3

Also locate point of contra flexure, if any. 07

(b) A shear force diagram for a beam of 5 m length supported on supports A and B is shown in Fig. 4. Draw load diagram and bending moment diagram for it.

07

Q.4 (a) 1. State the assumptions made in the theory of bending

2. State and explain equation of bending . 03

04

(b) A rectangular section of size 230 mm x 350 mm is used as a simply supported

beam of length 4.5 m. The beam carries a central point load of 50 kN. Find

maximum bending stress induced in the section.

07

OR

Q. 4 (a) 1. State and explain equation of shear stress for the beam.

2. Prove that for a rectangular section maximum shear stress is 1.5 times the

average shear stress.

03

04

(b) A rectangular section is used as a simply supported beam of length 5 m. It

carries a u. d. l. of 50 kN/m on its full length along with a central point load of

100 kN. Find width and depth of the section if maximum bending stress in the

beam is not to exceed 250 N/mm2. The depth of the section is twice the width

of the section.

07

Q.5 (a) 1. Define : Buckling load, Slenderness Ratio, Radius of Gyration.

2. Explain difference between Strut and Column. 03

04

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(b) Find value and nature of the force in the members of truss as shown in Fig. 5 07

OR

Q.5 (a) 1. Explain Perfect, Deficient and Redundant truss.

2. Explain difference between Beam and Truss. 03

04

(b) A concrete column, rectangular shaped of size 230 mm x 350 mm is 6 m long

and fixed at both ends. Find buckling load suing Eulers formula. Take factor of safety 3 and Ec=0.14 x 10

5 N/mm

2.

07

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. 1. . 2. :- , ,

03

04

1.5 m 20mm .

100 kN . ,

, .

E = 2 x 105 N/mm

2 .

07

. . 07 L 100 x75x10 mm

XX YY .

07

230 mm R. C. C. 6 20 mm .

750 kN .

. = Es/Ec = 15 .

07

. 1 . .

07

2 . 07

. 3 .

, .

07

4 5m A B

.

.

07

. 1. . 2. .

03

04

4.5 m 230 mm x 350 mm

. 50 kN .

07

4/4

.

. 1. .

2.

1.5 .

03

04

5 m .

50 kN/m 100 kN

. . 250 N/mm2

.

.

07

. 1. :- , , . 2. .

03

04

5

.

07

. 1. :- , .

2. .

03

04

230 mm x 350 mm 6 m

.

. Ec=0.14 x 105 N/mm2

3 .

07

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