Single and multi degree of freedom analysis of steel beams under blast loading

Nassr, Amr A.; Razaqpur, A. Ghani; Tait, Michael J.; Campidelli, Manuel; Foo, Simon

doi:10.1016/j.nucengdes.2011.10.020

Cited by 46 publications

(24 citation statements)

References 20 publications

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“…It should be noted that the pressure resulted by blast is multiplied to column width and is applied as uniform distributed throughout the column's external surface. This blast loading method is consistent with design references, such as [1,2] and other studies [7,13,34].…”

Section: Blast Loadingsupporting

confidence: 89%

“…The SDOF method is a simple approach with acceptable precision and is the basis of many references of analysis and design of structures under blast and explosion [1][2][3][4][5]. In the conducted studies it has been shown that equivalent SDOF system can model the behavior of steel beams and columns [6][7][8][9], slabs and walls [10][11][12] and reinforced concrete beams [13][14][15][16] under blast loading with acceptable accuracy. The SDOF method for modeling the response of retrofitted structural members in the face of blast has also been used [17,18].…”

Section: Introductionmentioning

confidence: 99%

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Preparing Pressure-Impulse Diagrams for Reinforced Concrete Columns with Constant Axial Load using Single Degree of Freedom Approach

Izadifard¹,

Mollaei²,

Omran³

2016

Int J Adv Tech

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In this paper, moment-curvature behavior of reinforced concrete column with constant axial load is determined using finite element method and then it is introduced to a single degree of freedom (SDOF) model based on EulerBernoulli theory. Using this SDOF model, dynamic response of the RC column under the blast loading is estimated. The introduced SDOF includes secondary moments (P-δ) effects, nonlinear behavior of the material and effects of strain rate on concrete and steel materials through the time calculation of the model. Results obtained from SDOF model for transverse displacement of RC column under blast loading is compared to analysis by finite element software OPENSEES. Then, introduced SDOF method is used for drawing Pressure-Impulse (P-I) diagram of the column with considering the presence of axial compressive load. According to the results, introduced SDOF model has simple and quick computations and accuracy of predictions is acceptable.P-δ effects and overall and local damages and their impact on the P-I diagram can be evaluated. However, this method due to the high complexity, high time of calculations and the need to have enough skills and experience of using software, for extensive parametric studies isn't very appropriate.In this paper, the flexural behavior (moment-curvature) of a reinforced concrete column section using finite element software of open system for earthquake engineering simulation (OpenSees) has been determined and introduced to the calculation of SDOF analytical model in order to estimate transverse displacement response of column under simultaneous compressive axial force and lateral loading of blast. The SDOF introduced model includes the effects of secondary moments (P-δ) and also the effects of high strain rates on the behavior specifications of concrete and steel rebar. In this method, to consider the effects of the existence of column axial loading (P-δ) the concept of reduced resistance function is used. Using the introduced process, P-I dimensionless curves have been plotted for reinforced concrete column. Figure 2 shows the distribution of stress and strain in the rectangular RC section at the ultimate state. Strain distribution in the height of the section has been assumed to be linear and curvature of section (θ) is equal to the slope of this line. Also, the tensile strength of concrete has been ignored. In the figure above, f yk is the yield stress of reinforcement steel, f cu is the ultimate strength of concrete, ε cu is the ultimate strain of concrete, xu is the depth of neutral axis in the ultimate state, b is the width, h is Equivalent Single Degree of Freedom Model

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Section: Blast Loadingsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Preparing Pressure-Impulse Diagrams for Reinforced Concrete Columns with Constant Axial Load using Single Degree of Freedom Approach

Izadifard¹,

Mollaei²,

Omran³

2016

Int J Adv Tech

View full text Add to dashboard Cite

show abstract

“…A simplified method, such as the SDOF analysis, is often used to estimate initial structural response while detailed finite element analysis is employed for detailed design (Bao and Li 2010;Biggs 1964;Nassr et al 2012).…”

Section: Some Of Those Challenges Beingmentioning

confidence: 99%

“…The following are some of the simplifications that limit the use of the equivalent SDOF model for detailed structural response analysis.  The first mode shape is assumed to govern the dynamic response of the structural component (Biggs 1964;Nassr et al 2012). This tends to be a good assumption when most of deflections occur during the plastic response phase which is dominated by the first mode shape and the blast loading is also uniform.…”

Section: [2-9]mentioning

confidence: 99%

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Effects of Blast Loading on Seismically Detailed Reinforced Concrete Columns

Kyei¹

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The rise in the number of terrorist attacks over the past few decades has led to growing concerns about the performance of buildings designed by well-established conventional design methods under blast loading. The concerns arise from the response of buildings and loss of lives in some of the more popular terrorist attacks such as those involving the Alfred P. Murrah Building, the Khobar Towers, and Marriott Hotel in Islamabad. Whereas most damage during these attacks was to non-structural elements such as infill wall systems and window glass, the collapse of the Alfred P. Murrah Building revealed that failure of load-bearing members can lead to widespread buildings failure. Thus, it has become imperative to investigate the performance of load-bearing building members to blast loading. More specifically, to quantify the blast resistance offered by buildings designed and detailed for other load types such as wind and earthquake.The effect of seismically detailed reinforced concrete columns on their blast resistance was investigated. Reinforced concrete columns not forming part of the seismic force resisting system were detailed according to CSA A23.3-04 -Design of Concrete Structures. The detailed reinforced concrete columns were subjected to blast loading in a numerical study using the high fidelity physics based finite element code (LS-DYNA). The numerical study was undertaken to investigate the effects of columns designed for different levels of seismicity in the National Building Code of Canada (NBCC) on their blast resistance.The results of the numerical study show that the lateral reinforcement detailing has a significant effect on the behaviour of columns under blast loading. When the reinforced concrete columns were detailed for high levels of seismicity by reducing the lateral reinforcement spacing in the plastic hinge region, the maximum lateral displacement was observed to reduce significantly in comparison with columns detailed with lateral reinforcement spaced for conventional design.ii Also, reducing the lateral reinforcement spacing at mid-height of the column, where plastic hinge formations is expected under blast loading, further reduced the maximum lateral displacement.The closely spaced lateral reinforcement in the seismically-detailed columns was observed to increase the blast resistance, especially to close-in blast loading.The effect of axial loading was also investigated in the numerical study. As the axial load ratio increased, the blast resistance of the concrete columns increased. However, at high, axial load ratios, the columns suffered concrete crushing in the compression zone leading to higher lateral displacements and instability. At higher scaled distances, increasing axial load ratios resulted in reduced maximum lateral displacements; with the seismically-detailed columns not offering any significant advantage over the conventionally-detailed columns.iii

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Analytical Models for Axially-Restrained Steel–Concrete-Steel Sandwich Panel Under Blast

Wang

2022

Innovations in Impact and Blast Protections

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Single and multi degree of freedom analysis of steel beams under blast loading

Cited by 46 publications

References 20 publications

Preparing Pressure-Impulse Diagrams for Reinforced Concrete Columns with Constant Axial Load using Single Degree of Freedom Approach

Preparing Pressure-Impulse Diagrams for Reinforced Concrete Columns with Constant Axial Load using Single Degree of Freedom Approach

Effects of Blast Loading on Seismically Detailed Reinforced Concrete Columns

Analytical Models for Axially-Restrained Steel–Concrete-Steel Sandwich Panel Under Blast

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