Strength of Materials - Steel Beams

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Discussion Overview

The discussion revolves around a homework problem related to the strength of materials, specifically focusing on selecting a steel beam for a floor structure and estimating a timber beam replacement. The scope includes theoretical and practical applications in structural engineering.

Discussion Character

  • Homework-related
  • Technical explanation

Main Points Raised

  • One participant expresses uncertainty about how to approach the problem and requests resources for understanding the relevant theory and examples.
  • Another participant notes that the problem involves calculating moment forces and suggests it may relate to Year 12 physics or first-year structural engineering.
  • A participant emphasizes the need to know allowable stresses and elasticity for both steel and timber, as well as the calculation of maximum bending moments and deflections, and mentions the importance of safety factors.
  • A later reply confirms the context as a first-year university question and reiterates the need for beam tables and notes on allowable stresses.
  • One participant requests specific formulas for maximum bending stress and deflections, indicating a desire for more detailed technical guidance.

Areas of Agreement / Disagreement

Participants generally agree on the need for understanding material properties and calculations related to bending moments and deflections, but there is no consensus on specific formulas or methods to solve the problem.

Contextual Notes

Participants reference the need for additional resources and notes, indicating potential limitations in the information provided and the reliance on external materials for complete understanding.

Who May Find This Useful

Students in structural engineering or materials science, particularly those working on homework related to beam selection and analysis.

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Homework Statement




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)

Homework Equations



Sorry, I have no idea.


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
 
Last edited by a moderator:
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Gonna need figure 4.

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

Year 12 phys or 1st year structural eng?
 
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.
 
thanks for your reply.

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

This is a first-year university question.
 
PhanthomJay said:
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.

thanks. this information is enlightening.

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

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