# Homework Help: Strength of Materials - Steel Beams

1. Oct 23, 2012

### physicx_1

1. The problem statement, all variables and given/known data

QUESTION 2 (Total 20 marks)

Figure 4 below shows a diagrammatic section of the floor of a typical house suspended over a garage. The steel beam shown in section spans 7.2 metres centre to centre of supports. The floor, including an allowance for the self weight of the beam, has a mass of 50 kg/m2 and the required live load is 1.5 kPa. Assume the beam is fully restrained against buckling.

(i) Based on the range of beams in the AISC tables attached to this paper, select the least weight steel beam that will meet the usual criteria for bending strength and movement. (18 marks)
(Note maximum deflection allowed is .003L where L is the span length)

(ii) Estimate the size of timber beam that could be used to replace the steel beam determined in part (i) above. (2 marks)

2. Relevant equations

Sorry, I have no idea.

3. The attempt at a solution

I honestly have no idea. If no one can show me the working, then can someone please link me to a good website / video / other resource that can teach me the theory and examples relevant to the question?

Our lecturer never uploads his lectures online, so its either you understand in class or you will be totally on your own.

Thanks very much.

http://img694.imageshack.us/img694/5582/capture1it.png [Broken]

Last edited by a moderator: May 6, 2017
2. Oct 23, 2012

### chief10

Gonna need figure 4.

Also, it's just a moment force type question.

Year 12 phys or 1st year structural eng?

3. Oct 23, 2012

### PhanthomJay

You will need to know the allowable stresses and elasticity of the steel and timber being used, and then calculate maximum bending moments and deflections. I assume you have some notes on this and beam tables nearby that tabulate moment and deflections for beams subject to load. Don't forget safety factors.

4. Oct 23, 2012

### physicx_1

Oops, my bad. I now have uploaded "Figure 4".

This is a first-year university question.

5. Oct 23, 2012

### physicx_1

thanks. this information is enlightening.

can you tell me the formula for it? (maximum bending stress and deflections)