Papers by Author: Seung Yong Lee

Abstract: The use of steel plates has been greatly increased in bridge construction, particularly for long-span bridges, and connections between the plates are made usually using high-tension bolts. However, the specifications on the use of large-sized high-tension bolts are not adequately stated in the currently available construction manuals. In order to provide further information on the use of the large-sized high-tension bolts, this study experimentally investigated the relaxation and slip behavior of M30 bolts with varying bolt size and plate thickness. In addition, numerical evaluation using FEM was performed to investigate the compressive stress occurred on the inside of bolt hole. The analyzed results were compared with the stress distribution measured from strain gages attached on the bolts and bolt holes. From the study presented herein, it was found that the relaxation was increased as the size of bolt increased, and that the M30 high-tension bolts developed slip coefficient greater than 0.4. The thickness of plate did not significantly affect the compressive stress distribution around the bolt holes.

Abstract: In the study herein, the fatigue test was conducted on the fillet welds of the load carrying cruciform joint, which is frequently used in the steel structures such as bridges, ships, etc. In addition, the fatigue stress was analyzed with respect to the different post-weld treatment. The treatment methods used include Toe Grinding, TIG Dressing, and Weld Profiling. The fatigue test was under constant amplitude with repeated load for these test specimens. In the load carrying full penetration fillet welded joints, regardless the conduction of the post-weld treatment or not, they all secured the fatigue strength of category "F", which exceeds the fatigue design specifications of BS Code. In the comparison of the fatigue strength upon the post-weld treatment, the fatigue strength tends to increase according to the order: Toe Grinding, TIG Dressing, and Weld Profiling.