ABSTRACT
Steel frame piers are commonly used for highway viaducts or bridges in urban areas in Japan. Thick plate might be used in beam-to-column connections of steel frame piers which are located in a higher moment area under earthquake load. Because thick plate may reduce low cycle fatigue strength of welded joints of steel frame piers, it is necessary to improve fatigue strength of welded joints. Although the fatigue design recommendation in Japan (Japan Society of Steel Construction, 1993) provides effects of plate thickness on high cycle fatigue strength, its recommendation still do not provide the effects of weld toe grinding on low-cycle fatigue strength.
Authors investigated the effects of plate thickness on low-cycle fatigue strength of cruciform welded joints (Kinoshita & Ueda, 2010), and the authors’ previous study showed that the decrease of low-cycle fatigue strength with the increasing of the plate thickness is larger than that of high-cycle fatigue strength. Based on the authors’ previous study, this study evaluates the enhancement in low-cycle fatigue strength of weld toes of cruciform welded joints by weld toe grinding.
The enhancement in low-cycle fatigue strength was investigated by bending fatigue tests under large plastic strain on cruciform welded joints as shown in Figure 1. Both 25 mm and 40 mm plate thickness were used for Specimens. Moreover, the enhancement by weld toe grinding were evaluated based on increases/decrease of local strain at weld toes obtained from elasto-plastic FEM analyses. Prior to the fatigue tests, local strain condition in the vicinity of the weld toe of tests using 25 mm plate thickness and 40 mm plate thickness was compared. Configuration and dimensions of the specimen with 40 mm thickness (<xref ref-type="bibr" rid="ref117_2">Kinoshita & Ueda, 2010</xref>). https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig117_1.tif"/>
As shown in Figure 2, it is found that not only weld toe grinding improve the low cycle fatigue, but also effect of plate thickness on the low cycle fatigue strength of weld toe ground joints seems to be less than that of as-welded joint due to changes of geometrical weld profile. Effects of the weld toe grinding on low-cycle fatigue strength. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig117_2.tif"/>
