Abstract: A joint connection between a concrete tower supporting a surface platform and a sea anchorage or foundation, comprises, an outer hemispherical socket shell which is adapted to be secured to the concrete tower and an inner head which has a hemispherical shell portion within the outer shell portion and a lower cylindrical portion which extends downwardly therefrom and is secured to a foundation plate having an opening therethrough for the passage of conveying lines. Lubricated slide shoe elements are disposed between the inner and outer shells to facilitate their pivotal interengagement. A support gimbal is secured within the inner head and a pull rod is connected to the gimbal and extends upwardly through the head and the outer shell and is connected to a beam mounted on the concrete foundation above hydraulic presses. The hydraulic presses comprise prestressing means connected to the pull rod to prestress it in a direction to urge the inner and outer shells into pivotal interengagement.