New Code Changes under the 2009 IBC

The evolution of building codes typically produce design provisions that are expected to create safer and more accurate designs. We as engineers expect building codes to advance the state of the art with each successive edition. The 2009 International Building Code (IBC) and the Building Code Requirements for Structural Concrete (ACI 318-08) have significant revisions affecting the design of tilt-up buildings, but in some cases not necessarily advancing the state of the art. For example, the latest ACI 318 edition is largely revising slender wall design back to match equations found in the old 1997 UBC. In addition, the latest IBC edition is carving out an exception to an especially troublesome code provision due to an oversight in the adoption process. This paper reviews the more significant code changes and describes the reasons behind their changes. Special attention is paid to the service level deflection revisions to slender wall design with the historical testing program conducted to develop the original slender wall provisions in the late 1970s.