You are viewing this question as it will appear in the manual grading interface. Return to the normal view when you are done.

Compute the normal stress

Consider the I-beam cross-section:

The table below has the geometric properties for different specifications for a steel beam:

Designation	h (in)	w (in)	Ix (in^4)	Iy (in^4)
S24 x 106	24.5	7.78	2,940	77.1
S24 x 100	24	7.425	2,390	47.7
S24 x 90	24	7.125	2,250	44.9
S24 x 80	24	7	2,100	42.2
S20 x 96	20.3	7.2	1,670	50.2
S20 x 86	20.3	7.06	1,580	46.8
S20 x 75	20	6.385	1,280	29.8
S20 x 66	20	6.255	1,190	27.7
S18 x 70	18	6.251	926	24.1
S18 x 54.7	18	6.001	804	20.8

For the beam designations indicated below, determine the maximum normal stress $\sigma_x$ assuming that the maximum moment is equal to $M_{max} = 3 \times 10^5 \rm\ lb \cdot in$.

Designation	$\sigma_x$
S20 x 96
S24 x 90
S18 x 70
S18 x 54.7

Note: this is an example of repeated variant question. Read more here.

Correct answer

Designation	$\sigma_x$
S20 x 96	`1.82335329341`
S24 x 90	`1.6`
S18 x 70	`2.91576673866`
S18 x 54.7	`3.35820895522`

Student view placeholder

In student views this area is used for assessment and score info.

Tools

Staff information

Question

QID:

demo/annotated/engBeamStress

Title:

Compute the normal stress

Variant

Started at:

2026-08-04 22:49:58 (CDT)

Duration:

Show/Hide answer

{
  "sigma1": 1.8233532934131738,
  "sigma2": 1.6,
  "sigma3": 2.915766738660907,
  "sigma4": 3.3582089552238807
}

This box is not visible to students.