George Solomos

• Hellenic Open University

Adobe is a traditional masonry made with sundried bricks of soil mixed with fibers and joined together using mud mortar. Constructions of adobe are spread in areas of the world currently involved into military operations. In the previous edition of ISIEMS, a ballistic phenomenological model developed by the authors for the penetration depth assessm...

This paper presents the results of an experimental research aimed at assessing the material performance of adobe bricks in compression for a wide range of induced strain rates, from statics to high velocity impact. Adobe connotes a traditional masonry whose bricks are made of sundried soil mixtures possibly reinforced with natural fibres and joined...

The work presents a numerical approach for the determination of the risk of injuries due to explosion events in large closed spaces, such as metro and railway stations, airport terminals, malls. The study is based on the numerical simulation of blast loading scenarios via fluid-structure interaction techniques. Such severe loading conditions induce...

The knowledge of material mechanical behaviour in different physical conditions is necessary to accurately simulate structural response using finite element methods, especially when complex physical processes, such as strain-hardening, large strains etc., are involved. In this context, the material characterization at different temperatures and str...

Adobe is one of the most ancient forms of masonry. Adobe bricks are sundried mixtures of clay, silt, sand and natural fibres locally available joined together using mud mortar. Adobe structures are largely spread in areas of the world prone to earthquakes or involved in military conflicts. Unfortunately, almost no literature concerns the dynamic as...

The current report provides a list of the available information sources with documents focusing on the protection of the so-called soft targets against terrorist attacks. The list aims at bringing to the interested security stakeholders information on measures to prevent potential attacks and/or mitigate their consequences.

A search and review of publicly available documents with guidance on the security of designated spaces against vehicle-ramming attacks has been conducted. The current report provides a list of these sources, which focus on the protection of public spaces, such as pedestrian areas, tourist sites, city squares or other perimeter protected areas. The...

Open-cell metal foams are a new class of cellular materials with structural features resembling those of lightweight load-bearing materials such as cancellous bones and wood. Their high stiffness-to-weight ratio coupled with their typical long, flat stress-strain response make them ideal candidates as cost-effective shock energy absorbers in crashw...

The determination of the blast protection level of civil engineering buildings components against explosive effects represents a design topic of crucial importance, in current practice. However, some key aspects of blast resistant structures design have been only marginally considered in the last decade, and currently still require appropriate regu...

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 des...

An increasing interest in lightweight metallic foams for automotive, aerospace, and other applications has been observed in recent years. This is mainly due to the weight reduction that can be achieved using foams and for their mechanical energy absorption and acoustic damping capabilities. An accurate knowledge of the mechanical behaviour of these...

The determination of the blast protection level of laminated glass windows and façades is of crucial importance, and it is normally done by using experimental investigations. In recent years numerical methods have become much more powerful also with respect to this kind of application. This report attempts to give a first idea of a possible standar...

The mechanical behaviour of concrete when subjected to impact or blast has still many aspects requiring further study. Dam concrete is characterized by large coarse aggregates, hence large specimen sizes are needed in order to study a representative volume of the material. Exploiting an innovative equipment, based on Hopkinson bar techniques, the d...

The development of an innovative apparatus, based on Hopkinson bar techniques, for performing large scale dynamic tests is presented and discussed. The activity is centered at the recently upgraded HOPLAB facility, which is basically a split Hopkinson bar with a total length of approximately 200 m, with bar diameters of 72 mm and where force pulses...

An increasing interest in lightweight metallic foams for automotive, aerospace, and other applications has been observed in recent years. This is mainly due to the weight reduction that can be achieved using foams and for their mechanical energy absorption and acoustic damping capabilities. An accurate knowledge of the mechanical behavior of these...

The structural behaviour of reinforced concrete is governed significantly by the transmission of forces between steel and concrete. The bond is of special importance for the overlapping joint and anchoring of the reinforcement, where rigid bond is required. It also plays an important role in the rotational capacity of plastic hinges, where a ductil...

Special Issue "Advancements in Design, Analysis, and Retrofitting of Structures Exposed to Blast" The determination of the blast protection level of laminated glass windows and facades is of crucial importance, and it is normally done by using experimental investigations. In recent years numerical methods have become much more powerful also with r...

It is important to protect critical buildings (shopping centres, government buildings and embassies), infrastructure and utilities, train and underground stations from being damaged, destroyed or disrupted by deliberate acts of terrorism, criminal activity and malicious behaviour. Normal regulations and building guidelines do not generally take int...

The development of the blast actuator experimental device is now entering the second phase, where reinforced concrete beams are used as specimens. This demanding phase needs a lot of support from numerical simulation to both predict and resolve possible failures and to validate the test results. The current report presents the comparison between th...

In this work a particular cement composite material for protection of structures and infrastructures against accidental actions, such as blast or impact, has been investigated. An experimental procedure has been developed in order to assess static and dynamic behaviour of energy absorbing cementitious composites. The granular cementitious composite...

The rail bound sector has become a preferred target of terrorist attacks because of its vulnerability, and the most frequent way to carry out these attacks has been the use of explosive devices. The aim of this study is to investigate the effectiveness of modelling detonation effects inside train carriages using explicit finite element (FE) techniq...

This study presents a numerical approach for the calculation of fatality risk caused by the impact of flying debris on the human body. Following an explosion, the formation of a large number of high velocity flying fragments, especially from glass panels, is very possible. The velocity, the mass and the shape of these projectiles define their hazar...

It is important to protect critical buildings (shopping centres, government buildings and embassies), infrastructure and utilities, train and underground stations against being damaged, destroyed or disrupted by deliberate acts of terrorism, criminal activity and malicious behaviour. Normal regulations and building guidelines do not generally take...

It is important to protect critical buildings (shopping centres, government buildings and embassies), infrastructure and utilities, train and underground stations against being damaged, destroyed or disrupted by deliberate acts of terrorism, criminal activity and malicious behaviour. Normal regulations and building guidelines do not generally take...

This technical report focuses on the calculation of blast parameters due to an explosion paying special attention to the blast wave decay coefficient needed for modeling the pressure-time curve with the Friedlander equation, and strongly influencing the value of the blast impulse. Engineers rely on a set of blast parameters that are available from...

Shock absorption often needs stiff but lightweight materials that exhibit a large kinetic energy absorption capability. Open-cell metal foams are artificial structures, which due to their plateau stress, including a strong hysteresis, can in principle absorb large amounts of energy. However, their plateau stress is too low for many applications. In...

Critical infrastructures may become the target of terrorist bombing attacks or may have to withstand explosive loads due to accidents. The impulsive load connected to explosions is delivered to the structure in a few milliseconds forcing it to respond or fail in a peculiar mode. With reference to the above scientific framework this work presents an...

Major efforts have been devoted in the last years to enhance transport security by detecting the vulnerabilities in the current public transportation structures, in particular rail and metro stations, and to propose measures to improve their resilience. The present work shows a complete study of an explosion event in a real metro station, by numeri...

A brief review of the technological advances of the Hopkinson bar technique in tension for the study of irradiated/non-irradiated nuclear materials and the development of this technology for large specimens is presented. Comparisons are made of the dynamic behaviour of non-irradiated and irradiated materials previously subjected to creep, low cycle...

Due to the recent threat levels knowledge of the behaviour of masonry materials under extreme dynamic loads has become very important. As a first step, it is necessary to establish whether the strength of these materials is increased with the strain rate that occurs for example under blast and impact loads. Thus the current investigation concerns t...

While in service, pipelines may from time to time be exposed to impact loads from anchors or trawl gear. A lot of parameters influence the behaviour of the pipeline during impact, e.g. the diameter and thickness of the pipeline, the impactor's mass and velocity, and of course the material used. Also potentially influencing the deformation pattern i...

Direct tensile tests on cubic concrete specimens of 60 mm side were performed at strain rates from 1 S-1 to 10 S-1 by means of a modified Hopkinson bar. The results of 26 such high strain rate tests on two concrete types, with 5 and 10 mm maximum aggregate size, are presented in this paper. As reference for these dynamic tests, a series of 14 stati...

There is strong interest in employing lightweight metallic foams for automotive and aerospace applications, where weight reduction, and mechanical energy absorption and acoustic damping capacity are required. Knowledge of the mechanical behaviour of these materials, especially under dynamic loadings, is thus necessary. This work presents an extensi...

It is important to protect critical buildings (shopping centres, government buildings and embassies), infrastructure and utilities, train and underground stations against being damaged, destroyed or disrupted by deliberate acts of terrorism, criminal activity and malicious behaviour. Normal regulations and building guidelines do not generally take...

This work presents a finite element approach for modeling longitudinal wave propagation in thick cylindrical rods with circular cross-section. The formulation is based on simple time domain response of the structure to a properly chosen excitation, and is calculated with an explicit finite element solver. The proposed post-treatment procedure ident...

The compression behavior of aluminum cenosphere syntactic foam has been studied and full stress–strain diagrams have been obtained for strain rates ranging from quasi-static to 1400/s. The foam exhibits peak stress at a strain of about 5%, especially during quasi-static compression, and the maximum value of stress around this strain is used to exam...

This work presents the stages of development of some innovative equipment, based on Hopkinson bar techniques, for performing large scale dynamic tests of concrete specimens. The activity is centered at the recently upgraded HOPLAB facility, which is basically a split Hopkinson bar with a total length of approximately 200 m and with bar diameters of...

The purpose of this work is to assess the dynamic mechanical behaviour of a commercial glass similar to that of the laminated glass structures used for protection and security applications in buildings. In particular, the study has been focussed on the influence of the strain-rate on the compressive (standard compression test) and tensile (splittin...

In this paper, several material models are analyzed in order to represent and compare the behaviour of laminated glass subjected to blast loads. LS-DYNA and EUROPLEXUS are used for numerical simulation. These codes have different capabilities to describe the mechanical problem, especially the failure behaviour. The results of the simulations are co...

The influence of venting areas built from glass on the peak pressure and impulse of explosions due to high explosives is investigated. The pressure-time function of an air blast wave resulting from a high explosive is different from that of a gas or dust explosion. Its peak pressure is higher but the duration of the positive phase is much shorter....

Land mass transport systems have an open architecture and are vulnerable to terrorist attacks. In case of an explosion inside trains or stations, the risk of injuries and fatalities may be mitigated by properly strengthening and optimizing these structures. This risk depends on the peak overpressure and impulse, which are estimated here using numer...

Aufgrund terroristischer Anschläge sind Baustrukturen auch Explosionen ausgesetzt. In der vorliegenden Untersuchung werden numerische Simulationen verwendet, um die Auswirkungen von Detonationen in schienengebundenen Massenverkehrsmitteln zu untersuchen. Es werden verschiedene Parameter für die Detonation innerhalb eines Waggons variiert. An einem...

The effects of explosions inside trains and the subsequent risk of injuries and fatalities have been investigated. The work has been carried out through numerical simulations with models developed in the explicit finite element program Europlexus. Fluid–structure interaction calculations have been performed capturing all blast wave propagation phen...

The influence of venting areas built from glass on the peak pressure and the impulse of explosions due to high explosives is investigated in this paper. The pressure-time function of an air blast wave resulting from a high explosive is different from that of a gas or dust explosion. Its peak pressure is higher but the duration of the positive phase...

In case of a terrorist bomb attack the influence and efficiency of venting areas in tubular structures like train carriages is of interest. The pressure-time function of an air blast wave resulting from a solid charge is first compared to that of a gas or dust explosion and the capability of a venting structure to fly away is assessed. Several calc...

The dynamic behavior of the bond slip between a deformed reinforcing bar and plain concrete has been experimentally investigated by employing Hopkinson bar techniques. Pullout tests with various specimen types (unconfined, confined, cast-in-place, post-installed etc.) have been performed. Pullout of the steel rebar and splitting of the concrete cyl...

Numerical simulation tools have been developed suitable for the assessment of the physical vulnerabilities of rail transport infrastructures to explosion loads, mainly due to terrorist bomb attacks. The source term, the air medium and the structure are properly modeled using the computational framework of the explicit finite element code Europlexus...

Terrorist attacks in New York have shocked the world community showing clearly the vulnerability of air transport in such events. However, the terrorist attacks in Madrid and London showed that land mass transport infrastructure is equally vulnerable in case of similar attacks. The fact that there has not been substantial investment in the domain o...

Reliable material models for concrete behaviour at higher strain rates are necessary for the design and assessment of concrete structures subject to impact and blast. This information should be obtained from experiments performed on large-size concrete specimens (up to 200 mm side cubes) with aggregates of realistic maximum size (16?32 mm). Such ty...

An analysis was undertaken to estimate the total annual dollar benefit, to airlines and other airspace users, of air Traffic Flow Management (TFM). Two major components of TFM were considered: managing airport volume and managing airspace during severe weather. Using Total Airport and Airspace Modeler (TAAM), the phenomenon of airport demand volume...

Owner: Ezio, Added to JabRef: 2009.11.11

Research on the United States (U.S.) National Airspace System (NAS) has sought answers to the following questions: Is there measurable excess flying time in the NAS? If so, where does it occur? Using aircraft track and flight information for multiple years, we have discovered a significant level of excess flying time when using a "best observed" fl...

The tensile dynamic behaviour of anchors in concrete has been experimentally investigated by employing Hopkinson bar techniques. Dynamic pull-out tests with two anchor size diameters have been performed, concrete cone breakout failure has been predominantly induced, and full force-displacement curves have been obtained. The test results show that...

The strain-rate sensitivity of concrete in tension has been investigated employing Hopkinson bar techniques. The devices used have allowed the successful testing of large specimens with real size aggregates. Full stress-strain curves, including the softening branch, have been obtained for several strain rates. The use of bar bundles for holding the...

An investigation of strain rate, temperature and size effects in three nuclear steels has been conducted. The materials are: ferritic steel 20MnMoNi55 (vessel head), austenitic steel X6CrNiNb1810 (upper internal structure), and ferritic steel 26NiCrMo146 (bolting). Smooth cylindrical tensile specimens of three sizes have been tested at strain rates...

Tests on tubular columns made of the aluminium alloy 6060-T4 under axial and oblique, quasi-static loading have been performed. The columns were fixed at one extremity, while a concentrated force was applied at the other through a rigid collar. Empty and foam-filled columns were tested for load angles equal to 0, 5, 15 and 30 degrees with respect t...

In order to allow more reliable predictions on the lower head response under core melt-down conditions, the temperature distribution has been analysed including the natural convection in the corium pool. Furthermore, the mechanical models and the failure criteria have been improved based on the RUPTHER and FASTHER experiments where typical temperat...

The failure strains for a large variety of specimens from reactor pressure vessel material will be investigated. Of special interest is the dependence of the failure strains on the size of the specimens. The research program and first results are outlined. Based on the findings limit strains will be proposed which should be acceptable under severe...

The results obtained during a testing program for tensile behavior over a large range of strain-rates (10-6 to 10 s-1) are summarized in this paper. The tests have been performed on cube specimens of 200 mm and 60 mm sides with aggregates of 5, 10 and 25 mm size. The high strain-rate tests have been carried out using a large Hopkinson bar bundle eq...

Uniaxial tensile tests have been performed on smooth and notched specimens with three different diameters and in a large range of strain rate and at different temperatures. A modified Hopkinson bar is used for the high strain rates tests for the small diameter specimens (3 mm) and the Large Dynamic Testing facility of the Joint Research Centre of I...

Constitutive equations are usually calibrated only trough the experimental results obtained by means of uniaxial tests because of the lack of adequate biaxial experimental data especially at high strain rate conditions. These data are however important for the validation of analytical models and also for the predictions of mechanical behaviour of r...

1 The application of a large Hopkinson bar bundle (bar transducers) as precision crash test technique of vehicle body cross-sections is proposed. This technique is under development at the Joint Research Centre (JRC) of the European Commission [1] and some successful results have already been obtained. The overall objective is to measure accurately...