Presented at SEAOC Spring Seminar Series: San Francisco, CA, March 14, 2012, pages 1-9.
The 2009 International Building Code (IBC) has in its scope some significant revisions that greatly affect the design of tilt-up concrete buildings, but to the lay engineer it appears that some of these provisions are a step backwards. With the IBC’s referencing standards including ACI 318-08 (concrete) and the 2008 NDS SDPWS (timber), these documents have significant changes that become effective with the adoption of the IBC. 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. Other changes in timber design are mostly administrative or incorporating errata from the last code cycle.
This paper provides the background for these changes and reviews their impact to tilt-up concrete building design and wall panel design. In addition, a historical context is provided where if may provide some clarity.