To learn more, view our Privacy Policy. To browse Academia. Log in with Facebook Log in with Google. Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Vladimir Sigmund. Hrvoje Draganic. A short summary of this paper. The aim was to become familiar with the issue of blast load because of ever growing terrorist threat and the lack of guidelines from national and European regulations on the verification of structures exposed to explosions.
The blast load was analytically determined as a pressure-time history and numerical model of the structure was created in SAP The results confirm the initial assumption that it is possible with conventional software to simulate an explosion effects and give a preliminary assessment of the structure. It is shown that, with the present knowledge Introduction and common software, it is possible to perform the analysis of structures exposed to blast loads and to The terrorist activities and threats have become a evaluate their response.
In the case of Explosions structures an effective mitigation may also be thought in the terms of structural resistance and physical integrity. If Explosive is widely used for demolition purposes in: the structures are properly designed for these abnormal military applications, construction or development works, loads damage can be contained.
Additionally, in order to demolitions, etc. It is, also, a very common terrorist ensure safety of existing structures against such events, an weapon as it is available, easy to produce, compact and evaluation procedure for their inspection and eventual with a great power to cause structural damage and retrofit is needed. Estimated quantities of explosive in various Within the Eurocodes these types of loads are not vehicles are presented in Tab.
Trunk of a large car There are no guidelines on such topics. On the other hand, Closed van this topic is the interesting one in military circles and Closed truck 2.
Nevertheless, a number of publications are available in the public domain and Truck with two trailers Analysis of structures under blast load requires a good understanding of the In order to be able to use explosives they have to be blast phenomenon and a dynamic response of structural inert and stable, which means that the explosion is a elements.
The analysis consists of several steps: a triggered, rather than a spontaneous reaction. The estimate of the risk; b determination of the explosion is a phenomenon of rapid and abrupt release of computational load according to the estimated hazard; c energy.
Speed of the reaction determines the usefulness of analysis of the structural behaviour; d selection of the explosive materials that can be condensed, solid or liquid.
Most of the explosives detonate by a In this paper we have explored the available literature sufficient excitation and convert into a very hot, dense gas on blast loads, explained special problems in defining under high pressure that presents a source of strong these loads and explored the possibility of vulnerability explosive wave.
Only about one third of the total assessment and risk mitigation of structures with standard chemical energy is released by detonation. The remaining structural analysis software with limited non-linear two thirds are released slowly in the blasts as the explosive products mix with the surrounding air and burn.
Sigmund The explosion effects are presented in a wave of high- There are various proposals for the calculation of the intensity that spreads outward from the source to the main explosion parameters. As the wave propagates, it decreases in Brode [12] gives the following values for the peak strength and speed Fig. The first W step in quantifying the explosive wave from a source other than the TNT, is to convert the charge mass into an R — distance from the centre of a spherical charge, m equivalent mass of the TNT.
It is performed so that the W — charge mass expressed in kilograms of TNT. Specific energy of different explosive types and Newmark and Hansen [13] proposed the use of the their conversion factors to that of the TNT are given in following values: Tab.
Sigmund Djelovanje eksplozija na konstrukcije Where p— is the maximum value of negative pressure 3. They are enhanced by the refraction 9 within the structure. In addition to this, depending on the Z degree of confinement, high temperatures and the accumulation of gaseous products of chemical reactions And the corresponding specific impulse at this stage, in the blast would produce more pressure and increase the is—, is given by: load duration within the structure.
Appropriate ventilation reduces strength and duration of pressure so the effect of pressure is different in structures with openings and structures without 3 openings. Explosion as a loading 3. However, unknown factors may lead to the overestimation of the structural capacity to blast loadings. As the wave propagates through the air, the wave Unexpected shock wave refraction, design methods, front encircles the structure and all its surfaces so that the quality of construction and materials, interaction with whole structure is exposed to the blast pressure.
The ground, are different for each particular structure. This a the characteristics of explosives that depend on the increased value of the charge weight is called the type of explosive material, released energy size of "effective charge weight". Explosion loadings can be divided into two main Time record of the explosion pressure wave is usually groups according to the confinement of an explosive described as an exponential function in the form of charge: confined and unconfined.
This change in pressure over time is shown Confined Partially confined in Fig. The height limitations of these explosions are two to three times of If the rectangular structure is exposed to an the height of a one-story or two-storey structure. The explosion, it will be exposed to pressures on all its explosion near the ground is an explosion occurring near surfaces. Each surface suffers two concurrent components or on the ground and the initial pressure is immediately of the load.
Diffraction of explosion around the structure increased as a result of refraction on the ground. Sigmund slightly to the left as the diffraction ends. Drag force 3. As the shock front expands in surrounding volume of Refracted wave arises as the initial blast wave is refracted the air, the peak initial pressure is reduced and the and increased by reflection of the ground. Unlike an duration of the pressure increases.
Figure 4 Refracted wave of the explosion near the ground Figure 3 Behaviour of the wave during its pass around the structure Wave front comes to a particular location at the time tA, and after the increase to a maximum value of ps0, the peak pressure decreases to the value of atmospheric pressure at the time t0 what represents a positive phase. Figure 5 Parameters of the positive phase blast wave near the ground [6] 3. The refracted wave is the result of the initial wave amplification by refraction of the ground.
Through the front height are occurring variations in pressure, but for the analysis they are ignored, and are regarded as a plane wave across the front height. The parameters are calculated as for an explosion on the ground.
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Mlakar and Darrell Barker.
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