Experimental Research On Residual Stresses In The Welded Monosymmetric I-Section

Welded I-section is often used in steel beams. Monosymmetric I-Section has a better application value and economic benefits than double-symmetric I-section, and is more and more applied to practical engineering.Welding residual stress is produced for the existence of non-uniform temperature field. It is one of the factors affecting stability behavior which cannot be ignored. According to the present research, the distribution of residual stress on double-symmetric I-section is better studied than monosymmetric I-section. In this paper, the values and distribution of residual stress of monosymmetric I-section are proposed which lay the foundation for further research on establishing the model of residual stress and analyzing the influence of residual stress to the stability behavior of monosymmetric I-section.Among the mechanical methods for residual stress analyses the blind-hole method is widely used, due to its convenient operate, well applicability and economic and time saving. The residual stress of double-symmetric I-section is measured by the hole-drilling method. It comes out that experimental values are consistent with the distribution model. The residual stress of 15 monosymmetric I-sections are measured followed. Influences of parameters on the residual stress distribution are researched and the parameters include web height-thickness ratio, flange width-thickness ratio, flange width and welding sequence.The experimental results show that:(1) In the welding position of flange and web, residual stress present tensile stress while in the edge of the flange and the middle of web present compressive stress. The peak values of residual stress close to wide flange are greater than close to narrow flange.(2) Keep thickness of web unchanged, increasing with web height-thickness ratio, tensile residual stresses of flange and web have an unobvious tendency to decrease. Meanwhile, compressive residual stress of flange decrease and it of web increase.(3) When the thickness and width ratio of wide and narrow flange remain the same, the value and distribution of residual stress on web essentially unchanged with the increase of flange width-thickness ratio, but tensile and compressive residual stress of flange decrease.(4) Adding the width of wide flange merely, peak values and distribution of residual stress on narrow flange almost the same. Peak values of tensile residual on wide flanges and webs have a tendency to decrease unconspicuous while the peak values of compressive residual stress reduce significantly. When the width of narrow flange added only, the residual stress on wide flange almost keep the same. Peak values of tensile residual on webs and narrow flanges decrease unobvious while the peak values of compressive residual stress reduce clearly.(5) Welding sequence effects residual stress on flange and tensile residual stress on web. Compressive residual stress of web is unchanged. The value of tensile residual stress decrease effectively when using zigzag welding. Peak values of tensile residual when welding wide flange first lower than the values when welding narrow flange first.