Factors to be considered in the design of steel structures

All the members in the structure ought to have adequate strength, stiffness & toughness to be sure proper funtioning in the work of service life. Members ought to have adequate strength, stiffness & toughness to be sure propoer functioning in the work of service life.

Reserved strength must be obtainable to cater for:

Aim is to prevent limit state from being reached.
one. Adaptations to site:

Occasional overloads - underestimated lots
Variability of strebgth of materials from those specified.
Variation in strength due to workmanship, construction practices.

If the structure is a building, for example, the designer must generate a plan that has suitable arrangement for rooms, corridors, stairways, windows, elevators, emergency exits etc & all this plan ought to be adapted to site so that it is feasible, accepted aesthetically & at a reasonable cost. This is called funtional planning.
two. Structural system:

structural system is dependent on funtional planning. Structural system includes the location of columns in the buildings, it is to be worked out with the funtional plan & sufficent space must be anticipated between completed ceiling & completed floor for location of columns.
three. Structural analysis:

One time lots are defined & design is laid out, structural analysis must be performed to choose internal forces that will be produced in various members of the framework. Assumptions must be made & it ought to be ensured that structure in point of fact also behaves as it is meant to (& as it was assumed to behave).
four. Proportionality of members:

Members must be proportioned with factor of safety in mind.
five. Factor of safety:

Variability of the material with respect to strength & other physical properties
Uncertainity in the expected lots
Precision with which internal forces are calculated
Possibility of corrosion
Extent of damage, loss of life
Operational importance
Quality of workmanship

The development of design specifications to provide suitable values of the margin of safety, reliability & probability of failure must take in to consideration the following factors.