Experimental Study of Residual Stresses in Q550GJ High-strength Steel Welded H-type Sections

For promoting the application of high strength steel in steel structure, the distribution of Q550GJ high-strength steel welded H-type sections was studied. The mechanical properties of Q550GJ steel were researched firstly. The result shows that the yield strength, tensile strength and elongation of the steel are consistent with the present specification. And its yield ratio is lower than 0. 85. Secondly 7 columns of 550GJ high-strength steel with welding H-type sections were designed and manufactured. The distributions of the residual stresses in these columns were researched experimentally by the partition method, and the effects of the different parameters were analyzed. The analysis results show that there are bigger residual tensile stresses in the middle of the flanges and near the welded regions of the web, the biggest stress is lower than the yield stress of the steel, and the changes of the residual tensile stresses are irregular. There are constant residual compression stress in the middle of the overhanging regions of the flanges and the web, the residual compression stress become smaller as the increasing of the width-thickness ratio. And the residual stresses of other regions of the column are transferred from the tensile stresses to the compression stresses.