The use of higher steel grades in building elements

Sammanfattning: Structural steel is one of the main building materials used commercial. Its strength is its formality and high yield strength which allows less material overall. Steel is often divided into steel grades such as S275, S355, S420 and so forth. The purpose of this thesis is to look at the strength and weaknesses of the different steel grades and how the area gets effected by higher steel grades. This is done by looking at a real life project where only S355 is used and optimizing for S355, S420 and S460. This is done to shred some light on how much of an improvement the upgrade of steel grade may allow. For each steel grade an optimized cross section is created with the goal of having the lowest area possible. The difference in area for the optimized beams will act as the benchmarking for projected reductions. This optimization is done with the help of Python and follows Eurocode. When looking at the case study, the projected weight reduction is 4,2% for S420 and 7,2% for S460 compared to S355. This reduction is higher on some beams and lower on others. The main driving force for the higher reduced beams is the possibility to utilize more than one type of load condition, example both momentand shear force. Out of the 12 beams, beam 10 have the highest reduction between S355 and S420 which land around 10%. Between S355 and S460 Beam 12 comesin at a area reduction of 14%. As the higher steel grades have a higher equivalent CO2 emission the reduction of equivalent CO2 is lower than the area reduction. The projected reduction of equivalent CO2 for a switch from S355 to S420 is 3,3% and the reduction between S355 and S460 are 5,0%