17) Blast analysis of integrated framing assemblies at openings in insulated concrete form wall construction (USA, 2012)

ABSTRACT: Insulating concrete forms (ICF) have become increasingly common in commercial projects. In ICF wall construction, wall sections are built by stacking blocks atop each other prior to pouring concrete. A block consists of two foam panels with a cavity between connected by plastic webbing. ICF wall construction has several advantages over traditional assemblies of CMU and stick-frame walls, including: improved structural performance (demonstrated by wind projectile tests, ICF homes surviving hurricanes, and preliminary blast testing), energy efficiency, and speed of construction. STALA® integrated framing assemblies (IFA) were developed by STALA® Integrated Assemblies, LLC to streamline framing of openings in ICF wall construction. The IFAs act as the opening formwork and reinforcement. Protection Engineering Consultants (PEC) and STALA® performed an analytical study to evaluate IFAs used to frame ICF wall, door and window openings subjected to blast loads. The main goal was to develop design guidance for ICF walls with IFAs for Department of Defense (DoD) loads while meeting the DoD low level of protection (LLOP) response criteria (UFC 04-010-01). PEC developed a non-composite resistance function for each ICF wall and IFA combination for use in single-degree-of- freedom (SDOF) analysis program, specifically SBEDS v4.0. Design tables were constructed for DoD charge weights and standoffs based on the results of the SDOF analyses. The design tables illustrate how IFAs impact ICF wall blast performance as a function of opening width and clear spacing. In general, IFAs improve the performance of the typical ICF wall, such that all cases analyzed meet the DoD LLOP response criteria when subjected to DoD charge weights at conventional construction standoffs. This paper presents a summary of our assumptions, analyses, results, and recommendations for future work.