LOAD AND EFFECT

WHAT IS LOAD?

        Forces acting on a body in its surface is generally called as LOAD. Body forces like gravity,inertia etc. are not included in LOAD.In this blog you will get LOAD AND EFFECT of those loads.

TYPES OF LOAD :CLICK HERE

        There are different types of loads based on in which point of the body the load actually applied.These can be classified as-

a) Normal load

b) Shear load

a) Normal load -(P1 and P2)

          Loads applied in the direction or parallel to the direction of longitudinal axis is called Normal load.This load can be further classified as-

i) Axial load 

ii) Eccentric axial load

b) Shear load -(Q1,Q2,R1 and R2)

          Loads applied in the direction or parallel to the direction of any of the transverse axis is called Shear load.This load can be further classified as-  

i) Transverse shear load

ii) Eccentric transverse shear load

EFFECTS OF DIFFERENT TYPES OF LOAD :CLICK HERE

i) Axial load -(P1)

          Axial load produces Axial stress in structural members acting along longitudinal axis i.e. in z-axis and uniform in every point of y-axis .Therefore we can conclude that axial LOAD AND EFFECT of aixal load is :

             

Axial stress, σ  = P/A (N/mm2)

where, P is the load and A is the area of cross section

ii) Eccentric axial load -(P2)

          As shown in fig-  the Eccentric axial load can be converted to axial load   and a couple  and hence it produces axial stress as earlier and bending stress which also acting in the direction of z-axis but in y-axis it is not uniform as shown in fig-  .Thus bending stress and axial stress both will act at yz - plane.

Bending stress, σ  = M/Z (N/mm2)

where M is constant i.e. M=P.e and

 Z is the section modulus and Z= I(xx)/y

CLICK HERE  for more about section modulus.

iii) Transverse shear load -(Q1 and R1)

         This type of loads produces Shear stress and Variable bending stress in structural member. Shear stress will act on xy - plane and varies along y-axis.Variable bending stress varies in z-direction also since here the bending moment M varies in z-direction according to bending moment diagram (BMD) which you will get in next blog..

The average shear stress is, τ =P/A (N/mm2)

Again, Variable bending stress, σ  = M(z)/Z (N/mm2)

 where M(z) is the variable bending moment and 
Z is the section modulus and Z= I(xx)/y (for Q1 load)

                                               or

                                                      I(yy)/x (for R1 load)

CLICK HERE  for more about section modulus.

iv) Eccentric transverse shear load -(Q2 and R2)

         This type of load produces shear stress  and variable bending stress as earlier and in addition to this it also produces torsional shear stress.Again torsional shear stress will  varies in cross section but not in any particular axis.It will vary in radial direction.Therefore we can conclude that Eccentric transverse shear LOAD AND EFFECT of it is as follows:

Torsional shear stress, τ  = T/Z(p) (N/mm2)  

where T is the torsional moment and T=P.e and
Z(p) is the polar section modulus and Z(p)= I(xx)+I(yy)

CLICK HERE   for more about polar section modulus.

 In the above fig-05 torsion due to load Q2 is shown and the torsional moment is clockwise in nature.