Lintel Testing for Reduced Shear Reinforcement in Insulating Concrete Form Systems

Authors: NAHB Research Center Inc.    

The purpose of this test program is to investigate the structural capacity and performance of the concrete lintels typically used in ICF construction. Lintels are reinforced concrete structural elements that support loads above openings in concrete walls. In the Prescriptive Method lintel spans were calculated using the Building Code Requirements for Reinforced Concrete (ACI 318-95) [2]. According to ACI 318-95, shear reinforcement is required for all ICF lintels in the Prescriptive Method. Shear reinforcement is generally difficult to install in ICF systems and, therefore, adds to the construction costs.

Results from this research program indicate that shear reinforcement for the ICF lintels in the Prescriptive Method is overly conservative and may be eliminated without sacrificing performance in span less than about 4 ft. (1.2 m). Consequently, future modifications to the Prescriptive Method and ACI 318-95 should be considered to result in more efficient utilization of ICFs in residential construction. Additional experimental and analytical work is recommended to expand this cost-effective benefit to ICF lintels that are longer in span.

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