Composite pre-stressed structural member and method of forming same

A method of forming a composite, pre-stressed structural member of the type having an upper molded surface supported by a lower support member comprising:

• connecting a lower support member having a flange at or near the neutral axis with respect to a vertical deflection of the support member to the upper side of a mold so that deflection of the mold causes deflection of the support member and such that support member connector means extend downwardly into said mold;
• supporting the mold and lower support member so that deflection of the mold and lower support member can occur;
• filling the mold with a moldable material which hardens to form a composite structural member with said lower support member;
• deflecting the mold during hardening of the moldable material such that the support member is placed in a pre-stressed condition to form a composite, pre-stressed structural member upon hardening of the moldable material;
• and
• after hardening of the moldable material, inverting the composite, pre-stressed structural member such that the lower support member is beneath and supports the hardened moldable material and such that the composite, pre-stressed structural member has a neutral axis with respect to vertical deflection which is above said flange.