Analyzing SMI Concrete for Adaptive Reuse
by D. Matthew Stuart
Owners and developers are increasingly opting, for many reasons, to convert existing buildings for new uses.
If no drawings are available for an older building, a structural engineer will often turn to industry resources to try and determine the nature and capacity of the existing structural system. Available information is then used to confirm that the facility meets the current building code requirements or to determine what strengthening or remediation must occur to accommodate the new use intended by the architect or owner.
If available general information is inadequate, the structural engineer must resort to either expensive nondestructive testing or exploratory demolition methods to try to ascertain the nature and capacity of the structure. In some cases, it becomes necessary to abandon parts of the building in place and construct independent structures around the existing one in order to support any new imposed loads or uses with assured safety.
Some existing structural systems that are no longer applied in current practice can still be adapted or reanalyzed for safe reuse today. One such system is the Smulski (SMI), or circumferential, system.
The Smulski System
The SMI system of designing reinforced concrete flat-plate slabs was developed by Edward Smulski, a consulting engineer from New York City, prior to the 1920s. The system was unique in that the primary flexural reinforcement consisted of concentric rings of smooth reinforcing bars supplemented with diagonal and orthogonal trussed bars placed between the supporting columns and radial hairpin bars located at the columns.
Discuss this article in the Architecture Forum...
This article is reprinted from the September 2007 issue of STRUCTURE magazine, with permission of the publisher, the National Council of Structural Engineers Associations (NCSEA).
The California State Printing Office in Sacramento, California, was built with a reinforced concrete structural system.
Photo: Bob Droke/ Historic American Buildings Survey
Extra Large Image
The structure of the California State Printing Office (1923) employs the so-called "mushroom" column and thickened slab shared in common by the Smulski (SMI) system and other contemporaries.
Photo: Bob Droke/ HABS
Extra Large Image
Click on thumbnail images
to view full-size pictures.