CHAPTER 2- ETABS FOR STEEL STRUCTURE

Analysis & Design Of Steel Frame

The physical properties of steel e.g. its durability, flexibility and strength, lend itself to many varied uses, one of which is in construction. The choice of structural steel work system as an alternative to reinforced concrete structures has many advantages. Steel can be easily formed and joined and its strength to weight ratio is the highest among common building materials. This makes it lightweight and yet strong as compared to concrete structures. Steel can also be recycled and is a good alternative building material that contributes to sustainable construction.Steel is dimensionally more stable, unlike other materials that shrink, expand, warp and twist with age. This leads to less settlement cracks or squeaking floors that require costly repairs. Steel buildings can be built with better tolerances and quality and are longer lasting.

The main problem of Steel is,its sensitivity to FIRE compaired to other construction material.

Now,I am presenting a TYPICAL RAFTER-COLUMN Frame (part of a large building)with pitch-roof analysis and design procedure by ETABS software.

Next figure will show Point load on various location of frame(kip).

Next figure will show Live load on Beam of frame(Lb/ft).

The above figure illustrates Lateral wind & Suction load on frame.Lateral load can be calculated by Bangladesh National Building Code(BNBC).

The code for steel building is AISC-ASD89. If stress ratio limit is not set up in your program you can set it as your choice.This value is the ratio of Demand stress to Capacity Stress which is widely known as load-Moment RATIO.

The above figure shows that the choosed section is safe & economic to bear all super-imposed load and selfweight of frame......for RAFTER section unity is 0.964 and for column it is 1.01,which can be wisely taken for designed section.

(Thanks)