A frame connection structure for use in connecting tubular or open channel elements one to another includes two or more inserts configured for respective insertion within the elements to be interconnected. Each of the inserts defines one or more channels therein, each channel being configured to be aligned with a respective aperture defined within the tubular/open channel element in which it is to be retained. A connection member is positioned within each aperture and its aligned respective insert channel. A portion of the tubular/open channel member proximate the aperture is displaced into the channel of the insert member whereby the that portion of the tubular/open channel member is disposed intermediate the sidewall of the channel and the connection member. The two inserts are configured to be connectable one to another. Each insert is therefore securely associated with a respective tubular/open channel member and the inserts are connectable one to another to facilitate the construction of a frame assembly.