Hardened Facades Effects on Structural Systems
Analytical Study and Test of Blast-Resistant Facades Effects on Structural Braced Frames
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Overview
Abstract
To ensure the safety of U.S diplomatic personnel overseas, the U.S Department of State (DoS) has developed facade retrofits capable of resisting high blast loads. Historically, these hardened facades have been primarily used in reinforced concrete frame structures that are perceived to perform better against high lateral forces generated by these facades. As the DoS builds and renovates existing steel-framed buildings, it is vital to understand the effects of hardened facades on steel structures to avoid potential collapse situations that would pose a threat to the building occupants.
An analytical study evaluated the global lateral response of steel frames representative of typical diplomatic facilities using hardened and conventional facades against high blast loads. Conventionally-designed steel frame buildings when used in conjunction with blast-resistant facades could be susceptible to failure due to the high blast reactions transferred to the Lateral-Force-Resisting-System (LFRS). However, when used with conventional facades, the rapid failure of the facade significantly reduces the loads on the LFRS. A test program was initiated to validate the findings from the study. Two tests have been planned using a full-scale, conventionally designed three-story steel braced frame. Test 1, in which a conventional curtainwall was installed on the steel frame structure has been conducted and the results validated the initial findings that conventional facades do not generate significant lateral loads in the LFRS. Test 2 which is in progress, will use a hardened facade and is expected to be performed in the fall of 2018. A review of the research program findings along with a brief discussion of new tools and methods to reduce blast reactions transferred to the LFRS are presented.
Authors
Aldo E. McKay, PE
Protection Engineering Consultants
amckay@protection-consultants.com
Cliff A. Jones, SE, PE, PSP
Protection Engineering Consultants
cjones@protection-consultants.com
Phillip Benshoof, PE
US Department of State Bureau of Diplomatic Security
BenshoofPC@state.gov
Keywords
Introduction
The U.S. State Department owns buildings and leases space in buildings for diplomatic purposes worldwide. Many of these buildings were not built considering any blast-resistant requirements, are not on an
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Background
Beginning in late 2010, an analytical study (McKay et. al., 2011) evaluated the global lateral response of different types steel frames representative of typical diplomatic facilities using hardened and conventional
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Research Method
First, an analytical study (McKay et. al., 2011) was performed to that included an extensive literature review and simple analytical modeling of a variety of typical steel building types. The
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Analysis Data
In order to be consistent in the evaluation of the different LRFS and to be able to relate their performance to existing consensus documents, PEC used the Structural Performance Levels
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Test 1 Data
Drift Displacement Response: Nine (9) displacement gauges consisting of string potentiometers and scratch gauges were used to measure the lateral (drift) displacement vs. time of the structure (as shown in
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Discussion of Results from Analytical Study and Test 1
Effects of Blast-Resistant (Hardened) vs. Conventional (Non-Hardened) Façade Systems – In the analytical study, all three and six-story buildings, shown in Table 2, were analyzed dynamically for reactions transferred from
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Conclusion and Future Work
An analytical study, performed using conventional structural analysis methods and tools, evaluated the lateral response of typical steel LFRS against the effects of blast loads using conventional and blast-hardened façade
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Acknowledgements
We would like to acknowledge State Department’s Bureau of Diplomatic Security Research and Development branch, and The Energetic Materials Research and Testing Center (EMRTC) for their contributions to this effort.
Rights and Permissions
American Institute of Steel Construction (AISC), 2010, Seismic Provisions for Structural Steel Buildings, AISC.
American Institute of Steel Construction (AISC), 2011, Steel Construction Manual, 14th Edition, AISC.
American Society of Civil Engineers (ASCE), 2010, Minimum Design Loads for Buildings and Other Structures, ASCE 7, ASCE.
American Society of Civil Engineers (ASCE), 2007, Seismic Rehabilitation of Buildings, ASCE 41, ASCE.
Department of Defense (DoD), 2014, "Unified Facilities Criteria (UFC) 3-340-02: Structures to Resist the Effects of Accidental Explosions," DoD.
Federal Emergency Management Agency (FEMA), 2000, Prestandard and Commentary for the Seismic Rehabilitation of Buildings, FEMA 356, FEMA/ASCE.
McKay, A., Bazan, M., Gomez, M., Marchand, K., Steel Frame Structure Performance in Blast Environments, Task 2
Analysis and Final Reporting, San Antonio, Texas, USA, December 2011.
McKay, A., Jones, C., Bewick, B., Test Plan Report for: Full Scale Test of Steel Braced Frame Structure, San Antonio, Texas, USA, March 2013.
McKay, A., Jones, C., Test Results Report for: Full Scale Test of Steel Braced Frame Structure, San Antonio, Texas, USA, March 2015.
McKay, A., Jones, C., and P. Benshoof, Investigation of Conventionally Designed Steel Frame Structures’ Inherent Resistance to Lateral Blast Loading, Test 1 Results. Paper presented at the Military Aspects of Blast and Shock Symposium (MABS 24), Halifax, Nova Scotia, Canada, September 2016.
U.S Army Corps of Engineers Protective Design Center (PDC), 2008, Methodology Manual for the Single-Degree-of-Freedom Blast Effects Design Spreadsheets (SBEDS), TR-06-01 Rev 1.
U.S Army Corps of Engineers Protective Design Center (PDC), 2008, Single Degree of Freedom Structural Response Limits for Antiterrorism Design), TR-06-08 Rev 1.