Abstract: An offshore structure and method of constructing same are disclosed. The offshore structure comprises a jacket assembly, a bottom tank secured to the bottom of said jacket assembly and a movable tank which is vertically slidable along said jacket assembly and which can be positioned on said bottom tank as a ballasting and storage tank. The offshore structure further includes a guide mechanism between said jacket assembly and movable tank to guide the vertical sliding of said movable tank, a frictional plate disposed on the contact surface between said bottom tank and movable tank so as to permit the two tanks to slide relative to each other in a given horizontal movement, and a buffer disposed between said jacket assembly and movable tank.

Abstract: A pipe joint construction comprises a main pipe having a circular section of outer diameter D and one or more branch pipes having a circular section of outer diameter d. The wall thickness To of the main pipe is increased at the interior of the main pipe to a value T at the portion to which branch pipes are welded. The angle .phi. subtended by the portion of increased thickness at the center of the main pipe is determined by the following relationship, that is,1>.phi./2.pi..gtoreq.(.alpha..sup.2 /k)(d/D).sup.1/4 (D/T).sup.1/2 (T/To)where .alpha. represents a rigidity ratio and k is a constant.