Frequently asked questions

Eccentrically Loaded Bolts

The bolt which will see the largest resultant force in a bolt group is the upper most bolt on the side of which the force is applied

Vp = vertical force per bolt = P/N

P = applied force (kips)

N = number of bolts

Ve = Force due to eccentricity = Pexc/Io

Xc = distance in X direction from centroid of bolt group to the subject bolt

The moment of inertia the sum of the distances of all bolts in the x and y directions if all bolts have the same diameter. Sum the distances of each bolt to the appropriate neutral axis:

Elongation and Contraction due to Axial Loading

The elongation or contraction of a beam due to an applied force is determined from the following equation:


P = applied force (kips)

L = length of beam (in)

A = cross sectional area (in2)

E = modulus of elasticity (ksi)

Elongation Due to Thermal Loading

The thermal elongation or contraction for steel is determined by the following equation:

D = Loa(t1 - to)

Lo = original length of beam (in)

a = coefficient of thermal expansion

t1 = new temperature (degrees Fahrenheit)

to = original temperature (degrees Fahrenheit)

Composite Beams

For composite members, the stresses in the beams can only be determined by analysis of similar materials. To do this, the stronger material should be converted to an equivalent area of the weaker material. This is done using the ratio of the moduli of elasticity n = E1/E2

Then calculate the equivalent width of the weaker material bequiv = bn

The member can then be analyzed as a single material.

Torsional Shear

Surcharge Load


  • Not all deflections are covered under beam chart equations
  • Moment Area Method can be used for the determination of angle and deflection
  • First draw the moment diagram
  • Determine the M/EI diagram by dividing points on the moment diagram by EI
  • The angle between tangents of two points is the area of the M/EI diagram between points
  • The deflection of a point from the tangent of another is area of the M/EI times the distance from the centroid of this area to the desired point of deflection

Horizontal Shear Stress

Horizontal shear stress

t = VQ/Ib

V = Applied Shear Force (kips)

Q = First Moment of the Desired Area = ay.

a = Cross Sectional Area from Point of Desired Shear Stress to Extreme Fiber (in2)

y = Distance from Centroid of Beam to Centroid of Area “a” (in)

I = Moment of Inertia of Beam (in3)

b = Width of Member (in)