March 31, 2009
The value of Metal Composite Material is being devalued by a small element of the International Building Code – Section 1407 – METAL COMPOSITE MATERIALS (MCM). A small footnote (a. – Table 1604.3 – DEFLECTION LIMITS) requires that the deflection from total loads be limited to L/60 of the span.
Appropriate deflection limitations should be determined by the following criteria:
- Assure structural integrity so that the panel system will remain on the building during design wind load conditions.
- Assure that sealant joints do not fail due to movement of panels during design wind load conditions because of excessive deflection.
- Assure that “permanent set” of panels is not visually objectionable after occurrence of design wind load conditions.
Deflection Limitations should be based upon the inherent qualities of the material. For example, Masonry walls are brittle and do not “flex”, therefore, they should be held to very strict Deflection Limitations – L/360. However, Metal Composite Material is very “flexible” so a more liberal Deflection Limitation is appropriate.
For these reasons, the deflection criteria should be changed for Section 1407 of the IBC to take better advantage of the ability of Metal Composite Material to “flex” during significant wind loads and return to its original condition without damage. This would allow for more efficient design of panels and therefore reduce the cost of the panel systems to the building owner.
Currently, a small group of MCM Fabricators actually design their panel systems to meet the Code and many more depend on the lack of inspection of Code Enforcement Bodies to not require compliance. So, you have the best Fabricators providing needless reinforcement competing with lower quality Fabricators not providing the unneeded reinforcement. Obviously, many Projects end up with lower quality panels because the better Fabricators are at a disadvantage.
If the Code is changed, the better Fabricators would be able to be more competitive, obtain more Projects, and Building Owners would receive better value. This is really change you can believe in.
So, let us start a discussion on how we can initiate this change for the advancement of our industry. Post you ideas on the Blog.
Thanks,
Ted S. Miller