while i design the top chord of the roof truss as compression member in order to calculate the net area of the section, the formulae shows that net area=load/all.compressive stress,and we assume the value between in the range of 60-80 for struct member
Version:
A) Passport characteristics of metal.
B) Safety factor.
C) Requirements of normative documents.
The formulas should also include the effect of the slenderness ratio.
The Tetmajer method, for example, makes use of a fictitious load, dependent on the slenderness ratio. This could perhaps justify the apparent difference of allowable values as indicated by you.
See the lessons of Prof. Martinelli (in english):
http://www.enzomartinelli.eu/MaterialeDidattico/stabilita/week03.pdf
The permisible stress is an engineering decision, based on the onformation about de application and other factors. Whe you "assume" you are following the guidance of a technical recomendation. In other hand, the design process is an structured process tha guides you to take a decision in the frame of different constrains, including economical factors. The first quistion is, why you are following the guidance of 80 MPa?
The engineering decision of the problem and the scientific decision are different things.
- Badges
- Science topic
- Similar topics
- Engineering
- Mechanical Engineering