Structural members with interlocked components

A hollow structural member comprising

• (a) a plurality of rigid wall sections cooperatively laterally enclosing an interior space, each of said wall sections having two parallel straight longitudinal free edges each disposed in proximate parallel relation to one of the longitudinal free edges of another of said wall sections to define therewith a joint between wall sections,
• (b) each of said wall sections having an inner surface bearing two longitudinal lips respectively disposed adjacent the longitudinal free edges of the wall sections and diverging inwardly from the inner surface thereof, each said lip defining with its associated wall section inner surface a recess opening toward the adjacent longitudinal free edge of the wall section, such that at each said joint there are two of said recesses respectively disposed on opposite sides of the joint and both opening toward the joint, each said lip having a free edge formed with a shoulder, and at least one of said joints being defined between longitudinal free wall section edges facing each other such that at said one joint, the recesses respectively disposed on opposite sides thereof open toward each other across the joint;
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• (c) means, receivable in the recesses adjacent the joints between wall sections, for interlocking the wall sections at said joints, said interlocking means including an elongated spline insertable in the recesses respectively disposed on opposite sides of said one joint and comprising a web for bridging said one joint inwardly of the wall sections adjacent said one joint and legs extending inwardly from opposite sides of said web for respectively engaging the lips defining the last-mentioned recesses behind their shoulders,
• (d) a longitudinal rib being formed integrally with and projecting outwardly from said web equidistantly from the sides thereof for engaging the facing longitudinal free wall section edges defining said one joint to limit the extent of lateral insertion of said spline into either of said last-mentioned recesses by acting as a stop for said lateral insertion;
• (e) at least a second of said joints being defined between longitudinal free edges of wall sections respectively having inner surface portions, immediately adjacent said second joint, oriented in substantially perpendicular planes such that the included angle between them is about 270.degree. and the recesses respectively disposed on opposite sides of said second joint open at about 90.degree. to each other;
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• (f) said interlocking means further including a second elongated spline, insertable in the recesses respectively disposed on opposite sides of said second joint, comprising a central portion bent longitudinally at about 90.degree. for bridging said second joint inwardly of said last-mentioned wall sections, and legs extending inwardly from opposite sides of said central portion for respectively engaging the lips defining the last-mentioned recesses behind their shoulders, said central portion bearing two longitudinal ribs respectively projecting inwardly therefrom toward the shoulders of the two last-mentioned lips for engaging the last-mentioned shoulders to limit movement of said central portion toward either of the last-mentioned shoulders.