Insulated Concrete Forms (ICF) As Blast-Resistant Barriers

摘要

Insulated Concrete Forms (ICF) have been used as residential and commercial building wall systems and in more recent years as floor and roof systems. The ICF consists of a reinforced concrete core formed between 2 panels of EPS (Expanded PolyStyrene foam) which acts as both permanent forms for the concrete core and the permanent insulation for the building. Typically only the concrete core with appropriate steel reinforcing is assumed to be the structural component of the building. Most of the ICF providers have load tables for resisting compression plus lateral pressure due to wind or seismic loads based on the thickness of the core and the amount and spacing of the steel reinforcement. Many building codes including the International Building Code (2009) include these materials in the chapters relating to concrete. FEMA 361 lists ICF as one of the materials to be used as a hurricane and tornado generated missile protection barrier with required core thicknesses depending on wind speed. This paper examines the possibility of the EPS foam panels contributing to the composite action of the ICF system to resist explosive blast loads. Both wind-generated missile impact tests and explosive blast tests have been conducted on ICF. The presence of the EPS outer form, which is usually about 2.5" thick, acts as a shock-absorbing cushion for both missile impact and the compression shock wave from an explosive blast. The plastic form ties that attach the inner EPS panel to the outer EPS panel restrains the hydro-static pressure of the uncured, wet concrete. These plastic ties and the inner EPS foam panel may also restrain any concrete fragments from penetrating into the interior of the building. This paper will summarize the results of these tests and present analytical evidence of the usefulness of not only the concrete core of the ICF, but also the EPS foam panels, as a blastresistant barrier.