Naito C (1), Olmati P (2), Trasborg P (3), Davidson J (4), Newberry C (5). Assessment of insulated concrete walls to close-in blast demands. Journal of Performance of Constructed Facilities 2014; in press.
(1) Associate Professor, Department of Civil and Environmental Engineering, Lehigh University, 13 E. Packer Ave, Bethlehem, PA 18015
(2) Associate Researcher, P.E., Ph.D., Faculty of Engineering and Physical Sciences, University of Surrey, GU2 7XH - Guildford, UK, Email: pierluigi.olmati@gmail.com
(3) Ph.D. Candidate, Department of Civil and Environmental Engineering, Lehigh University, 13 E. Packer Ave, Bethlehem, PA 18015
(4) Professor, Auburn University, Department of Civil Engineering, 238 Harbert Engineering Center, Auburn, AL 36849-5337
(5) Research Civil Engineer, Jacobs Technology, 104 Research Rd BLDG 9742, Panama City, FL 32403
Abstract
Intentional and accidental impulsive loads from high explosive detonations and munitions can result in significant damage to both civil and military facilities. One demand scenario of particular concern occurs during close-in detonation of high explosives. Even for resilient construction methods, such as reinforced concrete walls, these demands can produce undesirable effects including localized spall and breach. A popular form of exterior cladding in the U.S. consists of precast concrete insulated wall panels. These systems include an exterior concrete wythe, foam insulation layer, and an interior concrete wythe. While insulated wall panels are used to provide an energy efficient building envelope, the insulation layer can provide a means of mitigating spall and breach of the panel. Thus, the performance of insulated wall panels subject to close-in blast demands is investigated. Both numerical simulations and experimental tests are carried out in order to assess the structural response of this wall system to close-in explosions. The numerical solver LS-DYNA is adopted for carrying out the numerical simulations. The results indicate that the use of insulated concrete wall panels provides enhanced resistance to spall and breach. This improvement is due to the sacrificial performance of the exterior wythe of the concrete panel and the increased standoff distance between the protected face and the threat provided by the insulation layer.
Keywords
Close-in detonations; insulated wall panels; spall and breach; experimental tests; numerical simulations.
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Olmati P (1), Petrini F (2), Gkoumas K (2). Fragility analysis for the Performance-Based Design of cladding wall panels subjected to blast load. Engineering Structures 2014; in press.
http://dx.doi.org/10.1016/j.engstruct.2014.06.004.
(1) Associate Researcher, P.E., Ph.D., Faculty of Engineering and Physical Sciences, University of Surrey, GU2 7XH - Guildford, UK, Email: pierluigi.olmati@gmail.com
(2) Associate Researcher, Ph.D., P.E., Sapienza University of Rome, Department of Structural and Geotechnical Engineering, Via Eudossiana 18 - 00184 Rome (ITALY)
Abstract
This paper presents a probabilistic method to support the design of cladding wall systems subjected to blast loads. The proposed method is based on the broadly adopted fragility analysis method (conditional approach), widely used in Performance-Based Design procedures for structures subjected to natural hazards like earthquake and wind. The cladding wall system under investigation is composed by non-load bearing precast concrete wall panels. From the blast design point of view, these wall panels must protect people and equipment from external detonations. The aim of this research is to compute both the fragility curves and the limit states exceedance probability of a typical precast concrete cladding wall panel considering the detonations of vehicle borne improvised explosive devices. Moreover, the limit states exceedance probability of the cladding wall panel is estimated by Monte Carlo simulation (unconditional approach) in order to validate the proposed fragility curves.
Keywords
Performance-Based Blast Engineering; fragility analysis; concrete cladding wall panels; cladding system.
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Olmati P (1), Trasborg P (2), Naito CJ (3), Bontempi F (4). Blast resistant design of precast reinforced concrete walls for strategic infrastructures under uncertainty. International Journal of Critical Infrastructures 2014; in press.
(1) Associate Researcher, P.E., Ph.D., Faculty of Engineering and Physical Sciences, University of Surrey, GU2 7XH - Guildford, UK, Email: pierluigi.olmati@gmail.com
(2) Ph.D. Candidate, Department of Civil and Environmental Engineering, Lehigh University, 13 E. Packer Ave, Bethlehem, PA 18015
(3) Associate Professor, Department of Civil and Environmental Engineering, Lehigh University, 13 E. Packer Ave, Bethlehem, PA 18015
(4) Full Professor, Ph.D., P.E., Sapienza University of Rome, Department of Structural and Geotechnical Engineering, Via Eudossiana 18 - 00184 Rome (ITALY)
Abstract
Extreme loads can have devastating effects on civilian structures since these buildings are not designed to withstand extreme events. Typical buildings and other critical infrastructures are particularly prone to external man-made attacks. This study focuses on probabilistic analyses, and investigates the probability of exceeding a given limit state of a precast concrete wall subjected to blast loads. The wall under investigation is a non-load bearing precast concrete panel used as exterior cladding for buildings. From the blast design point of view, these walls must protect people and equipment from external detonations. The aim of the paper is to compute both the fragility curves and the probability of exceedance of a typical precast concrete cladding system, considering a prescribed detonation of a vehicle borne improvised explosive device. To this aim non-linear dynamic analyses are carried out by the widely adopted equivalent single degree of freedom method. The fragility curves and the probability of exceedance of the precast concrete cladding wall are computed using Monte Carlo simulations.
Keywords
Performance-Based Blast Engineering; fragility curves; Monte Carlo simulation; precast wall panels; conditional approach.
