tngv752:
Can you be more specific as to what you need? Are you in the US? If so, most building codes reference (or defer to) the ANSI/TIA/EIA-222-F for Steel Antenna Supporting Structures.
Is your need for broadcast, 2-way, cellular(wireless), WiFi, or other?
Will it involve a stand alone structure, or will it incorporate a structure of another type such as a building, power line, etc?
Will you be involved with the structure or antenna erection? Or design of same?