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In the event of a bomb blast taking place outside a building at the ground level, a hemispherical pressure wave travels in all directions and impacts the buildings and other structures in its path. The exterior walls, windows, doors and the structural system are impacted. The pressure wave enters the building through broken glass at doors and windows, blast damaged exterior cladding and any other openings in the exterior of the building. The increase in ambient pressure experienced inside the building depends upon the area of openings in the exterior walls and the roof, the air pressure due to the blast at the exterior wall and roof surface, the duration of the blast and the volume of the interior space. Depending upon these factors, the interior pressure can increase above the threshold of human tolerance, thereby causing injuries to the occupants in the form of damage to lungs and eardrums, in addition to injuries caused by broken glass and other damaged building components. This paper will present a simple method of estimating pressure buildup near the exterior walls and other locations subject to leakage of blast pressure from the outside. The threshold of human tolerance to high air pressure will also be indicated. [ABSTRACT FROM AUTHOR]

The increasing number of terrorist attacks brings the need to research on the blast resistance of buildings and transportation systems. Most of these attacks are lastly concentrated on the so called “soft targets” as railways stations, airports, bus stations, shopping centers, etc. In them, high vulnerability is frequently given by fenestrations or novel glass façade systems in general. In this regard, the paper is focused on the analysis of the dynamic behavior of blast loaded glazing windows. Given a reference specimen geometry and wood or plastic frame representative of traditional or new fenestrations respectively, the blast performance of such system is assessed via analytical SDOF calculations. Refined Finite Element (FE) numerical simulations are then presented and discussed, as a preliminary outcome of further exploratory investigations. Following the actual research study, experimental tests will be in fact carried out on the same fenestration systems. [ABSTRACT FROM AUTHOR]

In recent years, improvised explosive devices has been an aspect of crusades by terrorist or movements around the world. The blast wave propagation of an explosive detonation can cause disastrous damage on the buildings, vehicles and also injuries to vehicle occupants. Full scale blast tests are expensive and time consuming but by using computational based numerical simulations can virtually predict these wave propagations and minimize the need of experimental testing. Computational fluid dynamics (CFD) is a common tool to do an analysis of free-field blast wave and against structure. This paper presents two different blast analyses; free field air blast and blast loading towards a structure using ANSYS FLUENT software. A high explosive of 1 kg blast peak overpressure data from an experiment has been patched at the specific domain of the symmetry plane. The computed results were found to be in agreement with theoretical and additional experimental data. The verified free field air blast model was expanded to study the blast loading response towards a structure. It was found that developed CFD can be further used to predict the blast wave propagation subjected to the vehicle structures or buildings. [ABSTRACT FROM AUTHOR]

Abstract: The design of all spatial scales in a manufactured environment is part of the architectural skills and knowledge. Therefore, an architectural design should be drafted to reduce the vulnerability of humans and buildings against unexpected events, such as terrorist attacks and bombardments. Human casualties and equipment destruction inside the buildings could be prevented by designing a suitable architectural space. This study addresses the absence of a codified and detailed criterion to evaluate architectural spaces and their design. Hence, all proposed indices for architectural spaces have been extracted using the ideas of experts in the field of architecture and explosives. Questionnaires were presented to 25 experts to weigh the effective indices using the analytic hierarchy process method. The human-oriented (ergonomic) characteristics of the building space is found to be the most important factor in facilitating crisis management, followed by the location of critical spaces. [Copyright &y& Elsevier]

Impulsive blast sound from activity at DoD facilities, generated by artillery firing or ordnance, or demolition explosions, can cause structural blast damage or adverse community impact. This paper provides a detailed model, not widely available, for the probability of such damage starting with models for blast pressure loading and blast duration as a function of distance and TNTequivalent weight of the blast charge. This is followed by summaries of statistical models for blast propagation and diffraction and reflection effects on blast loading on buildings. Then, analytical models for the velocity response of building structures to the blast loads and key evaluation of the stress response to this structural velocity are provided. All of this is supported by data on critical configuration and physical parameters of the various types of responding structure to the blast loads and a summary of the failure data for these structures to the blast loads. Emphasis is placed on blast damage to windows. The paper ends with a useful and extensive development of the Probability of Damage (POD) for structure to blast loading. A comparison is also made between predicted and actual window damage observed from an accidental explosion near an apartment complex. Two Appendices are provided for: (A), the TNT-equivalent weight for a wide range of explosives and ordnance and (B), a definition of the Step-by-Step procedures used to carry out computation of the POD from blast from military training operations for a wide range of structures but mostly windows. [ABSTRACT FROM AUTHOR]

The characteristic response of a structure to blast load may be divided into two distinctive phases, namely the direct blast response during which the shock wave effect and localized damage take place, and the post-blast phase whereby progressive collapse may occur. A reliable post-blast analysis depends on a sound understanding of the direct blast effect. Because of the complex loading environment and the stress wave effects, the analysis on the direct effect often necessitates a high fidelity numerical model with coupled fluid (air) and solid subdomains. In such a modelling framework, an appropriate representation of the blast load and the high nonlinearity of the material response is a key to a reliable outcome. This paper presents a series of calibration study on these two important modelling considerations in a coupled Eulerian-Lagrangian framework using a hydrocode. The calibration of the simulated blast load is carried out for both free air and internal explosions. The simulation of the extreme dynamic response of concrete components is achieved using an advanced concrete damage model in conjunction with an element erosion scheme. Validation simulations are conducted for two representative scenarios; one involves a concrete slab under internal blast, and the other with a RC column under air blast, with a particular focus on the simulation sensitivity to the mesh size and the erosion criterion. [ABSTRACT FROM AUTHOR]

Responding to the threat of terrorist attacks around the world, numerous studies have been conducted to search for new methods of vulnerability assessment and protective technologies for critical infrastructure under extreme bomb blasts or high velocity impacts. In this paper, a two-dimensional behavioral rate dependent lattice model (RDLM) capable of analyzing reinforced concrete members subjected to blast and impact loading is presented. The model inherently takes into account several major influencing factors: the progressive cracking of concrete in tension, the inelastic response in compression, the yielding of reinforcing steel, and strain rate sensitivity of both concrete and steel. A computer code using the explicit algorithm was developed based on the proposed lattice model. The explicit code along with the proposed numerical model was validated using experimental test results from the Woomera blast trial. [ABSTRACT FROM AUTHOR]

The resilience of a city confronted with a terrorist bomb attack is the background of the paper. The resilience strongly depends on vital infrastructure and the physical protection of people. The protection buildings provide in case of an external explosion is one of the important elements in safety assessment. Besides the aspect of protection, buildings facilitate and enable many functions, e.g., offices, data storage, -handling and -transfer, energy supply, banks, shopping malls etc. When a building is damaged, the loss of functions is directly related to the location, amount of damage and the damage level. At TNO Defence, Security and Safety methods are developed to quantify the resilience of city infrastructure systems (Weerheijm et al. 2007b). In this framework, the dynamic response, damage levels and residual bearing capacity of multi-storey RC buildings is studied. The current paper addresses the aspects of dynamic response and progressive collapse, as well as the proposed method to relate the structural damage to a volume-damage parameter, which can be linked to the loss of functionality. After a general introduction to the research programme and progressive collapse, the study of the dynamic response and damage due to blast loading for a single RC element is described. Shock tube experiments on plates are used as a reference to study the possibilities of engineering methods and an explicit finite element code to quantify the response and residual bearing capacity. Next the dynamic response and progressive collapse of a multi storey RC building is studied numerically, using a number of models. Conclusions are drawn on the ability to predict initial blast damage and progressive collapse. Finally the link between the structural damage of a building and its loss of functionality is described, which is essential input for the envisaged method to quantify the resilience of city infrastructure. [ABSTRACT FROM AUTHOR]

A transient non-linear dynamics analysis of the detonation of a landmine buried to different depths in water-saturated sand is carried out in order to determine the resulting impulse loading. The results obtained are compared with their experimental counterparts obtained using the vertical impulse measurement fixture (VIMF), a structural mechanical device that enables direct experimental determination of the blast-loading impulse. The mechanical response of the structural steel used in the construction of the VIMF and the hydrodynamic response of the TNT high-energy high-pressure detonation products generated during detonation of a mine and of the air surrounding the VIMF are represented using the standard materials models available in the literature. The mechanical response of the sand surrounding the mine, on the other hand, is represented using the present authors' recent modified compaction model [1], which incorporates the effects of degree of saturation and the rate of deformation, two important effects, that are generally neglected in standard constitutive 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. it resembles under-water explosion. [ABSTRACT FROM AUTHOR]