Question

While designing the member of a steel structure building.
Discuss the types of load that you will consider in the design?

Note:I need a lot of information on the question.
Thank you.

Answer 1

The major (primary) loads to consider are;

1. Dead Loads: The name of this load is different for different codes of practice. The Eurocode for example refers to this type of load as permanent actions. However, they all refer to the same thing. Dead Loads are loads that exist on a structure throughout the design life of that structure. Examples of dead loads includes the self weight of the structural members such as beams, walls, slabs and columns. Finishes e.g plastering, tiling and other forms finishes are also dead loads. Partition loads are also sometimes considered as dead loads but this is not always the case.
2. Variable Loads: As the name implies, variable loads are loads that change with time. Variable Loads can also be called imposed loads. Some examples of variable loads includes occupancy loads (loads from occupants of that structure), equipment loads, furniture and fittings and sometimes partition loads. Most codes of practice have standard values for imposed loads depending on the usage of the structure. It's important to know also that wind loads could be considered as imposed loads in areas where they are not dominant or for low rise structures. However, when wind forces are dominant, the are considered separately.
3. Wind Loads: This type of load exists mainly due to the fact that structures are exposed to the atmosphere. The effect of wind loads however is more pronounced on high rise structures than low rise ones. The effect of wind is also considered structures on or close to the sea. The larger the surface area of a structure exposed to the wind, the larger the effect of wind forces on that structure. Nowadays, engineers design aerodynamic structures! These type of structures prevent the formation of vortices[1] around the structure and as a result keeps the structure standing tall in the face of huge winds. The burj khalifa (tallest building in the world) is a example of such a structure.

These loads described hitherto are major loads to be considered. However there are other loads that could be considered when designing structures and I will just state them here so that I don't bore you with details. Thermal Loads, hydrostatic loads, seismic loads etc. The truth of the matter is that anything at all that can lead to the failure of a structure is a load. However, structural engineers only consider loads that have significant effects on a structure (for economical and practical purposes) and use those loads to design that structure. For example you don't expect buildings in non-earthquake prone regions to be designed against seismic loads. On the flip side, buildings or structures in earthquake prone regions have to be designed against seismic forces and so on and so forth. I could talk about his all day!, but I hope I have done a bit of justice to your question.

Many structure, if not all will be subjected to all type of the loads listed above at sometime in their life. But direct combination of all thus loads at their maximum can’t be considered as probable, for example it would not be probable to expect a full live load to occur simultaneously with a full snow load during a design level wind storm.Thus proper load combination is important to design economical as well as safe structure.