Question

1.What is a code of practice and what is its
purpose in structural design?

2.List the principal sources of uncertainty in
structural design and discuss how these
uncertainties are rationally allowed for in
design.

3.The characteristic strengths and design
strengths are related via the partial safety
factor for materials. The partial safety
factor for concrete is higher than for steel
reinforcement. Discuss why this should be so

4. Describe in general terms the ways in
which a beam and column could become
unfit for use.

Answer 1

SOLUTIONS

1. ​​​​Codes essentially speak to the minimum acceptable levels of safety for buildings and other construction projects. As such, codes vary depending on geography, materials being used, size of the project, etc. As such, design codes for building a bridge from concrete can be quite different than design codes for building a bridge from steel. Furthermore, what ype of bridge you build from steel would also impact on the design codes.

2. Uncertainties to be considered in structural design may be because of loads, materials, member imperfections.

Loads that are considered in design are predicted loads likely to act on a particular type of structure. There may be accidental loads, causing overloading of a part of the structure or individual members.

Materials possess wide variation in their properties esp soil and concrete. Also there may be imperfections caused in member during fabrication/casting, or while erecting this causes members to be stressed initially.

3. The factor of safety of steel is less than concrete because the percentage air void in the steel is very very less in comparison of concrete , and the main cause of development of crack are voids because the surface area of the cross section get reduces due to the presence of void (Stress = force/area ) and stress in the material get increase because area get reduced and the metarial tends to failure .

On the basis of this concept the FOS of steel is less because of very less percentage air void in comparison of concrete .

Secondly the other reason are steel are cast in well maintained moulds , casting process and temperature etc . The concrete has more FOS because of high percentage air voids in comparison of steel.

4. If beam or a column start showing deflection more than the specifications provided by the code of the country then beam and column are unfit for use. This is the most common case but beam and column is also considered as unfit if there is any kinds of scaling due to rusting in reinforcement.

  ​​​​​​THANK YOU