15.10: Probabilistic analysis of steel columns under blast induced loads

Karlos, Vasilis; Solomos, George; Larcher, Martin

doi:10.1002/cepa.452

Cited by 13 publications

(19 citation statements)

References 14 publications

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“…A comparative study determined the quantitative pressure changes due to effects of diffraction, superposition of shock wave of the incident pressure wave, and multi-reflection within the confined space. The blast assessment of structure and façades, which are shielded by circular columns, by using the standard free-field blast wave peak incident pressure values, as suggested by the US design code (UFC:3-340-2:2008, 2008) and the European JRC Technical Reports (Karlos and Solomos, 2011) constitutes a security risk. Those are implemented in software such as LS-DYNA or CONWEP and are normally used as “Standard Blast Loads” for structures (e.g.…”

Section: Resultsmentioning

confidence: 99%

“…The incident peak pressure can be calculated with the semi-empirical formula (1) (see Kinney and Graham, 1985, equation (6-2)). Other approaches, for example, from Kingery and Bulmash (1984), are summarized in a study by Karlos and Solomos (2011). For assessment of ps, the charge sizes W , the ambient pressure in front of the shock front p0=101.332 kPa, and the distance to the GP R=5.47 m are required, as shown in equation (1), where Z is the scaled distance.…”

Section: Verification and Validationmentioning

confidence: 99%

“…The specific scenario of circular columns built in front of a façade cannot be assessed by using incident pressure and respective reflected pressure, as known for the planar surface (e.g. Anderson et al, 2006; Karlos and Solomos, 2011; Kinney and Graham, 1985, among others), but demands a precise understanding of shock wave progression and interaction in the area between the façade and the back face of the circular columns standing in front of the façade. In the following text, this area is termed as confined space.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Peak overpressure and impulse due to diffraction over a cylinder and/or multi-reflection of a shock wave in structural design- Part I

Hahn

Mensinger

Rutner

2020

International Journal of Protective Structures

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The design and planning of structural components, such as columns, to resist blast loads is a complex task. Often standard free-field blast loads, specified in design codes or other literature, are used for the analysis of the object. These loads are then further increased or decreased depending on the topology of the surrounding geometry (Mach-Stem), the shape of the impacted object itself, and blast wave reflection. However, most of these research works focus purely on the assessment of the structural components itself, ignoring a complex fluid mechanics phenomenon such as diffraction, which is of particular interest when circular columns are standing next to each other or placed in front of a façade. The article addresses three main topics. First, the article answers the question whether the area behind the column is protected, meaning constituting a shadowed area. We present findings that the close area behind a column is subjected to higher pressure and impulse values as there would be without the column. Hence, the incident pressure sees significant pressure buildup due to diffraction. This pressure buildup is quantified using pressure increase factors and presented together with the accompanying impulse. Second, this pressure buildup is of relevance for realistic design of a façade behind the column, which is not covered in current design codes at all. We discuss relevant parameters in the design process. Third, directly coupled with the assessment of the pressure buildup behind the column due to diffraction is the assessment of pressure and impulse in the area behind the column due to multi-wave reflection at a façade, leading to a significant pressure and impulse scale-up, which might be relevant for design of a column and/or a façade. This article identifies gaps in understanding diffraction and subsequent multi-reflection of blast wave within a structural design framework and provides insights on how to establish safe design accounting for these effects.

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Section: Resultsmentioning

confidence: 99%

Section: Verification and Validationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Peak overpressure and impulse due to diffraction over a cylinder and/or multi-reflection of a shock wave in structural design- Part I

Hahn

Mensinger

Rutner

2020

International Journal of Protective Structures

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“…This source contains polynomial equations for calculating the main blast parameters of both incident and reflected blast waves from spherical and hemispherical bursts. Their metric version can be reproduced in the Unified Facilities Criteria (2008) and is included in Karlos and Solomos (2013). The relevant curves of the above formulations have been compiled and coherently compared below.…”

Section: Blast Wave Characteristicsmentioning

confidence: 99%

Analysis of the blast wave decay coefficient using the Kingery–Bulmash data

Karlos

Solomos

Larcher

2016

International Journal of Protective Structures

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A growing interest for the design of structures to sustain blast-induced loads has been observed in recent years as a result of the worldwide rise of terrorist bombing attacks. The blast loading is usually characterized by a sudden increase in the pressure followed by an exponential decay. The parameters of this pressure pulse are essential for design and can be found in various blast design manuals available in the open literature. One of the most widely used sources is a technical report by Kingery-Bulmash, which provides values for many blast parameters in diagrams and polynomial form. However, it does not include an equation for calculating the blast wave decay coefficient, necessary for constructing the pressure-time history of an explosion at a certain point. In this study, a review of the technical literature that contains expressions for the blast pressure decay coefficient is performed, and relevant comparisons have been made. New equations describing the decay coefficient of the Friedlander equation for both incident and reflected cases for free-air and surface bursts are proposed. These equations express the decay coefficient in terms of the scaled distance and are not valid for close-in detonations. They are entirely based on the Kingery-Bulmash data, and their accuracy is satisfactorily checked against new experimental results and their trends assessed through a sensitivity analysis. Accordingly, the positive phase of the pressure-time curve at a point can be reliably and efficiently generated.

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“…Ding et al, 2017 considers the effect of the blast load on the member capacity but does not distinguish between the different limit states. Karlos et al, 2017 presented failure curves for steel columns subject to blast loads using the probabilisitc models presented in Netherton & Stewart (2010). In the study global buckling was assumed as the predominant failure mode.…”

Section: Introductionmentioning

confidence: 99%

Probabilistic models for blast parameters and fragility estimates of steel columns subject to blast loads

Singh

Gardoni

Stochino

2020

Engineering Structures

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This thesis proposes a probabilistic framework to predict the failure probabilities of steel columns subject to blast loads. The framework considers the uncertainties in the blast phenomenon, the demands imposed on the column, and the capacities of the column for the limit states of flexure, local buckling and global buckling. As part of the work, we propose four probabilistic blast load models. For different types of explosives and atmospheric conditions, two models predict the incident and reflected peak pressure generated by the explosion and two models predict the incident and reflected positive time duration of the blast wave. The models are probabilistic to capture the associated uncertainties, including variations in the atmospheric conditions, the inherent variability in the blast load data even for identical experimental conditions, and model error. The blast load models are used to predict the structural demands (maximum internal moment and deflection) imposed by the blast on a column. The demand models are combined with strain-rate dependent capacity models for flexure and global buckling to estimate the conditional probability of failure (or fragility) of a steel column for given scaled distance. As an example, fragility estimates for different columns representative of typical columns in steel frames are developed. The results highlight the effect of column dimensions and axial load on the failure probabilities.

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15.10: Probabilistic analysis of steel columns under blast induced loads

Cited by 13 publications

References 14 publications

Peak overpressure and impulse due to diffraction over a cylinder and/or multi-reflection of a shock wave in structural design- Part I

Peak overpressure and impulse due to diffraction over a cylinder and/or multi-reflection of a shock wave in structural design- Part I

Analysis of the blast wave decay coefficient using the Kingery–Bulmash data

Probabilistic models for blast parameters and fragility estimates of steel columns subject to blast loads

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