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Article
Publication date: 7 March 2016

Yasser Sharifi and Hamed Aviz

Nowadays, with the expansion of terrorist operations around the world and also the dangers of accidental explosions, the need to design structures resistant to this phenomenon for…

Abstract

Purpose

Nowadays, with the expansion of terrorist operations around the world and also the dangers of accidental explosions, the need to design structures resistant to this phenomenon for the protection and safety of its citizens is inevitable. Tall buildings are one of the most important issues because of which those behavior should be investigated against the blast loading.

Design/methodology/approach

In this paper, the authors used a simple method for investigating the dynamic response of tall buildings with the combined system of framed tube, shear core and outrigger-belt truss located at different heights of the building’s that were subjected to blast loading. This proposed model is based on the development of a continuum model and the ruling equations that have been obtained using the energy principle predict the whole structure idealized as a shear and flexural cantilever beam with rotational springs at the belt truss location.

Findings

The mathematical procedure shows a good understanding of the structural behavior and is suitable for a quick evaluation during the preliminary design stage, which requires less time. Moreover, it was concluded that the present blast load idealization can be used to reasonably assess the response of tall buildings subjected to blast load.

Originality/value

The comparative analysis in this paper could give other engineers a simple analysis method for the preliminary analysis and design of tall building analysis. Numerical example is given to illustrate the ease of application and the accuracy of the suggested model.

Article
Publication date: 1 October 2020

Osama Bedair

This paper reviews engineering work developed for blast analysis and design of industrial/residential and ammunition storage facilities. The review also covers work done for…

Abstract

Purpose

This paper reviews engineering work developed for blast analysis and design of industrial/residential and ammunition storage facilities. The review also covers work done for progressive collapse analysis and blast deflectors.

Design/methodology/approach

The first part of the paper describes characteristics of various types of explosions. Empirical and numerical models that were developed to estimate structural capacity are reviewed. The structural idealization, theoretical basis, and merits of various methods are also described. The influence of various parameters affecting the structural performance is discussed.

Findings

The material of the paper captures recent engineering developments that can be used by practitioners for blast analysis and design for industrial and residential buildings. Little emphasis was given in the published literature to develop simplified analytical models that can be used in practice to compute the dynamic response of buildings subject to accidental explosions. Furthermore, analytical expressions are required to compute the reduction in the stiffness due to impact loading.

Originality/value

Current building codes address conventional live, dead, wind and earthquake loads. Very few guidelines are available in practice for design of buildings subject to blast loading. The objective of this paper is to review and piece together recent engineering work developed for blast analysis and design of industrial/residential buildings and ammunition facilities. The paper provides useful resource material for the engineers in practice using recent techniques to design these structures. The review covers past three decades that can be used as a baseline for future developments.

Details

Multidiscipline Modeling in Materials and Structures, vol. 17 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 8 August 2016

Mica Grujicic, S Ramaswami, Jennifer Snipes, Ramin Yavari and Philip Dudt

The purpose of this paper is to optimize the design of the advanced combat helmet (ACH) currently in use, by its designers in order to attain maximum protection against ballistic…

Abstract

Purpose

The purpose of this paper is to optimize the design of the advanced combat helmet (ACH) currently in use, by its designers in order to attain maximum protection against ballistic impacts (fragments, shrapnel, etc.) and hard-surface/head collisions. Since traumatic brain injury experienced by a significant fraction of the soldiers returning from the recent conflicts is associated with their exposure to blast, the ACH should be redesigned in order to provide the necessary level of protection against blast loads. In the present work, augmentations of the ACH for improved blast protections are considered. These augmentations include the use of a polyurea (a nano-segregated elastomeric copolymer)-based ACH external coating/internal lining.

Design/methodology/approach

To demonstrate the efficacy of this approach, instrumented (unprotected, standard-ACH-protected, and augmented-ACH-protected) head-mannequin blast experiments are carried out. These experimental efforts are complemented with the appropriate combined Eulerian/Lagrangian transient non-linear dynamics computational fluid/solid interaction analysis.

Findings

The results obtained indicated that: when the extent of peak over-pressure reduction is used as a measure of the blast-mitigation effectiveness, polyurea-based augmentations do not noticeably improve, and sometimes slightly worsen, the performance of the standard ACH; when the extent of specific impulse reduction is used as a measure of the blast-mitigation effectiveness, application of the polyurea external coating to the standard ACH improves the blast-mitigation effectiveness of the helmet, particularly at shorter values of the charge-detonation standoff distance (SOD). At longer SODs, the effects of the polyurea-based ACH augmentations on the blast-mitigation efficacy of the standard ACH are inconclusive; and the use of the standard ACH significantly lowers the accelerations experienced by the skull and the intracranial matter. As far as the polyurea-based augmentations are concerned, only the internal lining at shorter SODs appears to yield additional reductions in the head accelerations.

Originality/value

To the authors’ knowledge, the present work contains the first report of a combined experimental/computational study addressing the problem of blast-mitigation by polyurea-based augmentation of ACH.

Details

International Journal of Structural Integrity, vol. 7 no. 4
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 9 August 2013

M. Grujicic, J.S. Snipes, N. Chandrasekharan and S. Ramaswami

The purpose of this paper is to assess the blast‐mitigation potential and the protection ability of an air‐vacated buffer placed in front of a target structure under realistic…

Abstract

Purpose

The purpose of this paper is to assess the blast‐mitigation potential and the protection ability of an air‐vacated buffer placed in front of a target structure under realistic combat‐theatre conditions.

Design/methodology/approach

The blast‐mitigation efficacy of the air‐vacated buffer concept is investigated computationally using a combined Eulerian‐Lagrangian (CEL) fluid‐structure interaction (FSI) finite‐element analysis.

Findings

The two main findings resulting from the present work are: the air‐vacated buffer concept yields significant blast‐mitigation effects; and the buffer geometry and vacated‐air material‐state parameters (e.g. pressure, mass density, etc.) may significantly affect the extent of the blast‐mitigation effect.

Originality/value

The main contribution of the present work is a demonstration of the critical importance of timely deployment of the buffer relative to the arrival of the incident wave in order to fully exploit the air‐vacated buffer concept.

Details

Multidiscipline Modeling in Materials and Structures, vol. 9 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 10 October 2016

Mica Grujicic, Jennifer Snipes and S. Ramaswami

The purpose of this paper is to introduce and analyze a new blast-wave impact-mitigation concept using advanced computational methods and tools. The concept involves the use of a…

Abstract

Purpose

The purpose of this paper is to introduce and analyze a new blast-wave impact-mitigation concept using advanced computational methods and tools. The concept involves the use of a protective structure consisting of bimolecular reactants displaying a number of critical characteristics, including: a high level of thermodynamic stability under ambient conditions (to ensure a long shelf-life of the protective structure); the capability to undergo fast/large-yield chemical reactions under blast-impact induced shock-loading conditions; large negative activation and reaction volumes to provide effective attenuation of the pressure-dominated shockwave stress field through the volumetric-energy storing effects; and a large activation energy for efficient energy dissipation. The case of a particular bimolecular chemical reaction involving polyvinyl pyridine and cyclohexyl chloride as reactants and polyvinyl pyridinium ionic salt as the reaction product is analyzed.

Design/methodology/approach

Direct simulations of single planar shockwave propagations through the reactive mixture are carried out, and the structure of the shock front examined, as a function of the occurrence of the chemical reaction. To properly capture the shockwave-induced initiation of the chemical reactions during an impact event, all the calculations carried out in the present work involved the use of all-atom molecular-level equilibrium and non-equilibrium reactive molecular-dynamics simulations. In other words, atomic bonding is not pre-assigned, but is rather determined dynamically and adaptively using the concepts of the bond order and atomic valence.

Findings

The results obtained clearly reveal that when the chemical reactions are allowed to take place at the shock front and in the shockwave, the resulting shock front undergoes a considerable level of dispersion. Consequently, the (conserved) linear momentum is transferred (during the interaction of the protective-structure borne shockwaves with the protected structure) to the protected structure over a longer time period, while the peak loading experienced by the protected structure is substantially reduced.

Originality/value

To the authors’ knowledge, the present work is the first attempt to simulate shock-induced chemical reactions at the molecular level, for purposes of blast-mitigation.

Details

Multidiscipline Modeling in Materials and Structures, vol. 12 no. 3
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 14 June 2019

Chao Liu, Mingyang Yang, Haoyu Han and Wenping Yue

To study fracture characteristics of jointed rock masses under blasting load, the RFPA2D analysis software for dynamic fracture of rocks based on the finite element method and…

Abstract

Purpose

To study fracture characteristics of jointed rock masses under blasting load, the RFPA2D analysis software for dynamic fracture of rocks based on the finite element method and statistical damage theory was used.

Design/methodology/approach

On this basis, this research simulated the fracture process of rock masses in blasting with different joint geometrical characteristics and mainly analysed the influences of distance from joints to blasting holes, the length of joints, the number of joints and joint angle on fracture of rock masses.

Findings

The calculation results show that with the constant increase of the distance from joints to blasting holes, the influences of joints on blasting effects of rock masses gradually reduced. Rock masses with long joints experienced more serious damages than those with short joints. Damages obviously increased with the changing from rock masses without joints to rock masses with joints, and when there were three joints, the further increase of the number of joints had unobvious changes on blasting effects of rock masses. Joints showed significant guidance effect on the propagation of cracks in blasting: promoting propagation of main vertical cracks deflecting to the ends of joints.

Originality/value

The research results are expected to provide some theoretical bases in practical application of engineering blasting.

Details

Engineering Computations, vol. 36 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 February 2008

M. Grujicic, B. Pandurangan, G.M. Mocko, S.T. Hung, B.A. Cheeseman, W.N. Roy and R.R. Skaggs

Detonation of landmines buried to different depths in water‐saturated sand is analyzed computationally using transient non‐linear dynamics simulations in order to quantify impulse…

Abstract

Detonation of landmines buried to different depths in water‐saturated sand is analyzed computationally using transient non‐linear dynamics simulations in order to quantify impulse loading. The computational results are compared with the corresponding experimental results obtained using the Vertical Impulse Measurement Fixture (VIMF), a structural mechanical device that enables direct experimental determination of the blastloading impulse. The structural‐dynamic/ballistic response of the Rolled Homogenized Armor (RHA) used in the construction of the VIMF witness plate and the remainder of the VIMF and the hydrodynamic response of the TNT high‐energy explosive of a mine and of the air surrounding the VIMF are represented using the standard materials models available in literature. The structural‐dynamic/ballistic response of the sand surrounding the mine, on the other hand, is represented using our recent modified compaction model which incorporates the effects of degree of saturation and the rate of deformation, two important effects which are generally neglected in standard material models for sand. The results obtained indicate that the use of the modified compaction model yields a substantially better agreement with the experimentally‐determined impulse loads over the use the original compaction model. Furthermore, the results suggest that, in the case of fully saturated sand, the blast loading is of a bubble type rather than of a shock type, i.e. the detonation‐induced momentum transfer to the witness plate is accomplished primarily through the interaction of the sand‐over‐burden (propelled by the high‐pressure expanding gaseous detonation by‐products) with the witness plate.

Details

Multidiscipline Modeling in Materials and Structures, vol. 4 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 24 December 2021

Mohammadsina Sharifi Ghalehnoei

The purpose of this study is to develop the performance model of buildings designed by the seismic code 2800 against the explosion wave and determination of safety distance.

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Abstract

Purpose

The purpose of this study is to develop the performance model of buildings designed by the seismic code 2800 against the explosion wave and determination of safety distance.

Design/methodology/approach

Analytical models of three-, five- and ten story structures that used moment frame system and also a ten-storey building with shaer wall designed based on the seismic code 2800 in term of design and nonlinear analysis were generated for use with Perform-3D software. Extensive parametric analysis is executed on different explosive loads with 100, 500, 1,000 and 5,000 Trinitrotoluene, soil types 2 and 3, models eqs and eqbs, the number of story buildings and the effect of shear wall to determine the safety distance based on collapse threshold performance (CP) level criterion.

Findings

The results indicate that by increasing the explosives mass from 100 to 5,000 kg and the number of the stories three and five induce increasing the safety distance of CP level in buildings to 4.5 meter and 3 meter times, respectively. Ten-story structures modeled on shear wall show very good performance because of stiffness rising and high energy absorption. In addition, by increasing the stories from five to ten, the amount of the safety distance reduces the CP level to 3.9 meter times.

Originality/value

The results of this work are meaningful for explosion-resistant design and damage assessments of reinforced concrete moment framed structures subjected to explosive explosion.

Details

World Journal of Engineering, vol. 20 no. 3
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 16 November 2012

M. Grujicic, J.S. Snipes and N. Chandrasekharan

This paper aims to utilize purpose advanced fluid‐structure interaction, non‐linear dynamics, finite‐element analyses in order to investigate various phenomena and processes…

Abstract

Purpose

This paper aims to utilize purpose advanced fluid‐structure interaction, non‐linear dynamics, finite‐element analyses in order to investigate various phenomena and processes accompanying blast wave generation, propagation and interaction and to assess the blast‐wave‐mitigation potential of a piston‐cylinder assembly placed in front of the target structure.

Design/methodology/approach

The employed computational methods and tools are verified and validated by first demonstrating that they can quite accurately reproduce analytical solutions for a couple of well‐defined blast wave propagation and interaction problems.

Findings

The methods/tools are used to investigate the piston‐cylinder blast‐mitigation concept and the results obtained clearly reveal that significant blast‐mitigation effects can be achieved through the use of this concept. Furthermore, the results showed that the extent of the blast‐mitigation effect is a sensitive function of the piston‐cylinder geometrical parameters. Specifically, the mass of the piston and the length of the cylinder are found to be the dominant factors controlling the extent of the blast‐wave‐mitigation.

Originality/value

The work demonstrates that, when assessing the blast‐wave‐mitigation potential of the piston‐cylinder concept, it is critical that loading experienced by the piston be defined by explicitly modeling (fluid/structure) interactions between the blast wave(s) and the piston.

Details

Multidiscipline Modeling in Materials and Structures, vol. 8 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 3 July 2009

Haydar Uyanık and Zahit Mecitoğlu

The purpose of this paper is to develop a structural vibration control system by using a state observer which estimates system states using displacements measured from sensors.

Abstract

Purpose

The purpose of this paper is to develop a structural vibration control system by using a state observer which estimates system states using displacements measured from sensors.

Design/methodology/approach

Friedlander's exponential decay function is used for expressing the blast load model. A semiloof shell element is developed in order to account for piezoelectric effects. The composite plate is discretized by using the semiloof shell elements, and stiffness and mass matrices of the plate are obtained from the finite element model. In order to reduce the degrees of freedom of the finite element model, mode summation method is used with weighted modal vector including initial dominant modes in the dynamic behavior.

Findings

The structural vibrations are suppressed successfully and in an optimal way by using a state observer control system which estimates system states using displacements measured from sensors.

Originality/value

This paper shows, for the first time, that vibrations of a cantilevered composite plate subjected to blast loading are suppressed by the use of piezoelectric actuators. The state observer and optimal linear quadratic regulator are both used at the same time to suppress the vibrations.

Details

Aircraft Engineering and Aerospace Technology, vol. 81 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

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