Experimental Investigation into the Axial Compression of Welded Stocky Columns of Q690 and Q960 High Strength Steel

With the development of metallurgical technology, high-strength steel and ultra-high-strength steel with yield strengths of 460 MPa and above have been industrially produced in China, with production increasing year by year. These steels use heat treatment processes to obtain specific microstructural compositions, optimize their material properties and mechanical characteristics, and have outstanding advantages in terms of the stress performance of building structures, economic benefits and energy saving and emission reduction. However, some researchers believe that the microstructures of these high-strength steels are easily affected during the welding process due to the heat treatment process during smelting, resulting in the reduction of various mechanical properties in the weld heat-affected zone. Therefore, there is a great need to study and quantify this post-welding structural behaviour of high-strength Q690 and Q960 steel plates in practical sizes for the construction industry (e. g. 10 to 30 mm thickness). To address this issue, welding process specifications for Q690 and Q960 medium thickness plates were developed, and a comprehensive experimental study was carried out on a total of 36 short columns of high-strength steel to quantify the cross-sectional load carrying capacity of welded spliced short columns of high-strength steels Q690 and Q960 under axial compression with different welding heat inputs, and to analyse, in comparison with the design requirements of the current European Union norm EN 1993-1-1, that the applicability of the existing codes on short columns of high strength steel and ultra-high strength steel is also analyzed, experimental data are povided, and some opinions on the regulations of exising section classification are proposed.