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Chapter: Civil - Mechanics Of Solids - Transverse Loading On Beams And Stresses In Beam

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Important Question, Answer And Solved Problems: Civil - Transverse Loading On Beams And Stresses In Beam

Civil - Mechanics Of Solids - Transverse Loading On Beams And Stresses In Beam


TRANSVERSE LOADING ON BEAMS AND STRESSES IN BEAMS

 

1. What is beam?

 

Beam is structural member which is supported along the length and subjected to external forces acting transversely to the centre line.

 

 

2.  Define Shear force

 

Shear force at a section in a beam is defined as the algebraic sum of all the vertical forces acting on the beam either to the left (or) to the right of the section.

 

 

3.  Define Bending moment.

 

Bending moment at a section in a beam is defined as the algebraic sum of moments about the section of the beam either to the left (or) to the right of the section.

 

 

4.  Write four types of beams based on their types of supports?

 

a. Simply supported beams                b. Fixed beam

c. Cantilever beam                             d. Propped cantilever beam

 

5.  What are the different types of loading on a beam?

 

a. Concentrate load (or) point load   b. Uniformly distributed load

c. Non-uniform distributed load        d. Couple or moment.

 

6.     What are the different types of supports?

 

(i) Simply support (or) roller support

(ii) Pinned support (or) Hinged support

(iii) Rigid support (or) Fixed support

 

7.     What is a simply supported beam?

 

A beam supported or resting freely on the walls columns at its both ends is known as a simply supported beam.

8.     What is Cantilever beam?

 

A beam fixed at one end and free at the other end is known as a cantilever beam.

 

 

9.  What is continuous beam?

 

A beam which has more than two supports is called continuous beam.

 

 

10. What is overhanging beam?

 

If the one or both the end portions are extended beyond the support then it is called.

 

 

11. Define fixed beams.

 

A beam whose both ends are rigidly fixed or built-in walls is known as rigidly fixed beam or a built in beam.

 

 

12. What is transverse load?

 

A load which has more than two supports is called transverse load.

 

 

13. What is point load?

 

A load which is acting at a particular point is called point load.

 

 

14. What is uniformly distributed load?

 

A load which is spread over a beam in such a manner that the rate of loading 'w' is uniform throughout the length.

 

 

 

15. What is shear force?

 

It is the unbalanced vertical forces on the left or right section of the beam.

 

 

16. Define bending moment.

 

Bending at a cross section is the algebraic sum of the moments of all the forces which are placed either side from that point.

 

 

17. Write the relation between SF and BM.

 

The rate of change of BM is equal to the SF at the section dM/dx = - F

 

18.  A  clockwise  moment  M  is  applied  at     the  free  end  of  cantilever.  Draw  the  SF  and  BM diagrams of the cantilever.       

SF Calculation     SF diagram

SFA= 0

SF at B = 0

BM Calculation    BM diagram

BM at B = -M     

(Since for counterclockwise moment)

BM at A = -M

(BM at both the ends is same)

 

19. A simply supported beam of span 'l' is subjected to central concentrated load 'W'. What is the bending moment at the centre?

 

Bending moment at the centre Mc = Wl/4

 

 

20.            What is point of contra flexure? Whether point of contra flexure will occur in a cantilever beam?

 

The point where BM is zero after changing its sign is known as point of contra flexure.

 

 

21.            Whether point of contra flexure will occur in a cantilever beam?

 

The Point of contra flexure will not occur in a cantilever beam.

 

 

22. Define pure bending (or) bending stress.

 

Simple bending means flexure by pure bending moment without shear force.

 

23.            What are the assumptions are made in the theory of pure bending?

 

a)    The value of the young's modulus is the same for the beam material in tension as well as compression.

 

b)    The transverse section of the beam, which is a plane before bending, will remain a plane after bending.

c)     The material of the beam is homogeneous and isotropic.

 

 

24.            State the theory of simple bending.

 

If a beam is bent only due to application of constant BM and not due to shear then it is called simple bending.

 

 

25. Write down the bending equation.

M = f = E I y R

M - Moment of resistance I - Moment of inertia

f - Maximum bending stress

 

y - Distance from the neutral axis E - Young's modulus

R - Radius of the curvature

 

 

26. Define Section modulus

It is the ratio of moment of inertia about the neutral axis to distance of the extreme fiber from the neutral axis.

Section modulus Z = I / Y

27.  What is moment of resistance of the section?

 

It is the product of section modulus and bending stress at that section.

M = f x Z

 

28. What is a flitched beam? Why it is used?

 

A flitched beam means a beam of composite section consisting of a wooden beam strength ended by mild steel plates. It is mainly used to reinforce the material which has lower strength and reduce the cost.

 

 

29. Why flitched beam is used?

 

It is mainly used to reinforce the material which has lower strength and reduce the cost.

 

 

 

30. What is the value of maximum shear stress in a rectangular cross section?

 

The max shear stress in a rectangular section is 1.5 times the average stress.

 

 

31.  Write  down  the  equation  for  shear  stress  distribution  across  a  circular  section  with  radius.

 

R at a distance y from neutral axis.








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