provides research information on thread-fixed one-side bolt (TOB), which is anchored through screwed threads in the bolt hole. Although beam-column endplate connections have been studied by many researchers and been widely used in engineering applications, the standard high strength bolts are not convenient for the bolted beam to square tube column endplate connection. The one-side bolts, which can be installed and tightened from outside of the tube column, provide a solution for beam to closed section column bolted connections. This book introduces the basic principles and design methods regarding the failure modes, and the design method of load carrying capacity of endplate connection using thread-fixed one-side bolts.