Calculation of Blast Loads for Application to Structural Components. Administrative Arrangement No JRC 32253-2011 with DG-HOME Activity A5 - Blast Simulation Technology Development

This technical report describes a procedure that can be followed for the calculation of the loads to be applied to a structure as a consequence of a blast. The report considers explosions taking place outside a building, which are not addressed directly at the relevant European Standards (Eurocode EN1991-1-7) dealing with accidental loading scenarios. The aim is the production of a simple, self-contained guide enabling the structural engineer to conduct a preliminary design of buildings for possible terrorist attacks. Aspects of the theory of blast waves have been included at an introductory level. The approach of the empirical methods for the prediction of blast loads has been chosen, which is more straightforward and has resulted from extensive experimental testing. For the determination of the main blast parameters, several graphs and diagrams have been included, which have been collected and properly adapted from several authoritative sources. This should make the load calculation procedure easier to grasp and less demanding in terms of mathematical complexity and computational capacity. Selected case studies are also presented in order to demonstrate through simplified examples the steps that must be followed for the calculation of blast pressures on the surfaces of a structure.JRC.G.4-European laboratory for structural assessmen

Review on vehicle barrier protection guidance

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 list aims at bringing to the interested security stakeholders information on measures to prevent potential attacks and/or mitigate their consequences by properly designed and tested barrier systems.JRC.E.4-Safety and Security of Building

Review on Soft target/Public space protection guidance

The current document provides a list of the available information sources focusing on the protection of soft targets against terrorist and other types of malicious extremist attacks. The list aims at bringing to the interested security stakeholder existing documents with information and practical guidance on measures to prevent a potential attack and to mitigate the consequences, should such an attack materializes. The collected documents do not address critical infrastructure, but they mainly focus on the so-called soft targets, the term being used to represent vulnerable material or human assets, which in principle should not be specifically protected. However, such targets are often selected by terrorists in their effort to maximize casualties, inflict fear to the population and attain media coverage. The documents are grouped according to the following broad domains relating to soft targets: public places, education/religious/health installations, transport, building facades, urban resilience, security planning & risk management, policy/regulation/finance, people involvement, and drones. The referenced information sources originate from various countries and bodies, such as UK, France, Sweden, Czech Republic, USA, Australia etc. The list is quite comprehensive but it is limited to the publicly available documents and practically to those found in English and French.JRC.E.4-Safety and Security of Building

Analysis of blast parameters in the near-field for spherical free-air explosions

The report focuses on the calculation of blast parameters that are used for designing structural elements to resist blast induced loads. It addresses shortcomings encountered with the widely used relationships proposed in the Kingery-Bulmash technical manual. The parameter values in it have proven accurate for medium and large scaled distances, but serious doubts have been raised by researchers on their validity for small scaled distances, i.e. close-in detonations. As supporting experimental data in this distance range are scarce, numerical simulations have been employed in this investigation. The finite element code EUROPLEXUS is used to study the evolution of spherical blast waves and their parameter values for near and far-field explosions. Modelling of both the explosive (through the JWL equation) and of the air is made. The results from one-dimensional and three-dimensional analyses are favourably compared with those of other specialized programs and with limited actual test data. For the numerical discretisation mesh sensitivity studies are conducted and an equation is proposed that allows the use of a variable cell size in relation to the scaled distance, that ensures both accurate results and reduced computational costs. From the analysis it is revealed that the Friedlander equation cannot capture the overpressure-time behaviour at small scaled distances as it fails to take into account the effect of the expanding detonation products. At such distances it is also found that there is a big difference between the peak overpressure and positive impulse values proposed by Kingery-Bulmash and those calculated through the numerical simulations, the latter being considerably higher. As a result a new set of equations in terms of scaled distance are proposed that provide improved parameter accuracy for points close to the detonation centre.JRC.G.4 - European laboratory for structural assessmen

Protection against Unmanned Aircraft Systems: Handbook on UAS Risk Assessment & Principles for Physical Hardening of Buildings and Sites

The purpose of the current handbook is to provide guidance against the growing international threat posed by the malicious use of Unmanned Aircraft Vehicles (UAS), commonly referred to as drones. The focus narrows down into recommendations for a robust and usable approach for the physical hardening of non-military infrastructures and public spaces against this borderless phenomenon. It addresses shortcomings encountered in the design of such security solutions and aims at producing a simple, self-contained guide to enable the selection of appropriate measures that are able to mitigate and/or deter potential attacks. Towards assessing the relevant risk, a detailed analytical procedure is illustrated for identifying the weaknesses of the potential targets and calculating the parameters that influence the likelihood of manifestation of a UAS-driven attack and its consequences. A methodological approach is proposed that facilitates the development of attack scenarios depending on the vulnerabilities of the examined asset, assisting their comparison in terms of severity and probability of occurrence. Advice is provided for the introduction of physical hardening measures that may effectively treat the evaluated threat. This measures span from physical protective measures to concealment or disguising efforts to make the target less attractive. Such an approach overcomes many of the legal and operational shortcomings of counter UAS technologies and provides a variety of methods for securing a site.JRC.E.3 - Safety and Security of Building

A guide to key information on the protection of Public Spaces

The purpose of the current document is to provide a list of the available information sources focusing on the protection of public spaces against terrorist and other types of malicious extremist attacks. Public spaces represent vulnerable assets under public or private ownership, that allow open, easy access and may attract a great number of people. Their vulnerability lies to the fact that they usually lack specialised protective measures and consequently, can be attacked by aggressors using both simple and more elaborated tactics. Such targets are often selected by terrorists in their effort to maximize casualties, attain media coverage and inflict fear to the population. The information sources presented herein aim at raising awareness and bringing to the interested security stakeholder existing documents with specialized information and practical guidance on available measures that facilitate the prevention of a potential attack and mitigation of the consequences, should such an attack materialize. The documents are grouped according to the following broad domains relating to public spaces: public space/soft target definition, protection of public places during events, protection of education/religious/health sites, protection of retail/entertainment facilities, protection from hostile vehicles, risk assessment/management, protection of transport facilities, protection of critical infrastructures/buildings and protection against Unmanned Aerial Systems (UAS). The referenced information sources originate from various countries and bodies, such as UK, France, Sweden, Czech Republic, USA, Australia etc. and they mainly focus on aspects of physical protection against terrorism threats. The list is mainly limited to publicly available documents and practically to those found in English, German and French.JRC.E.4 - Safety and Security of Building

A numerical framework to support the certification of barrier testing

This report describes the numerical framework to study the impact of vehicles on barriers, as part of the vehicle ramming protection strategy development. The numerical framework covers the set-up of the desired parameters of the model and also the computational efficiency of the analysis. Numerical results of passengers and heavy weight vehicle impact against bollards are presented. Finally, we discuss how the numerical simulations can assist in obtaining a better certification of the Hostile Vehicle Mitigation (HVM) systems via guidelines and enhancement of the existing specifications. It is expressed the clear need to develop European models for different vehicle types to support the development of barriers and to foster the European market of barriers.JRC.E.4-Safety and Security of Building

Guideline - Building Perimeter Protection: Design Recommendations for Enhanced Security against Terrorist Attacks

The purpose of the current document is to provide guidance to security and law enforcement officials, building/site owners, venue organizers, state organizations, engineers and other stakeholders that are in charge of securing facilities and critical infrastructures against the growing international terrorist threat. The focus of the report narrows down into recommendations for a robust and usable approach for the physical protection of infrastructures against this borderless phenomenon. It addresses shortcomings encountered in the design of such security solutions and aims at producing a simple, self-contained practical guide to enable the selections and installation of elements that are able to stop and/or deter potential terrorist attacks. A detailed analytical procedure is illustrated for identifying the weaknesses of potential terrorist targets and assess the relevant risk for different terrorist tactics. Advice is provided for the introduction of protection measures against both external and internal explosions and design methodologies are presented for minimizing the likelihood for the development of a progressive collapse mechanism. Moreover, specialized perimeter physical protection measures are proposed that may successfully restrict unauthorized vehicle and intruder access, supplemented by the employment of modern digital technologies, such as video surveillance, smart sensors and video analytics. The novel and emerging threat landscape is also addressed, such as the malicious use of Unmanned Aircraft Systems, requiring new response strategies that call for the adoption of state-of-the-art counter technologies.JRC.E.4-Safety and Security of Building

Methodology for numerical simulations of vehicle impact on security barriers considering soil-barrier interaction

Vehicle Security Barriers (VSBs) are frequently utilised in urban settings to defend against vehicular terrorist attacks. They may come in various forms, including bollards, street furniture and landscape features. The effectiveness of such barriers is usually assessed through a singular vehicle impact test, in accordance with various test standards and guidelines. The substantial cost of impact tests significantly restricts the amount of impact scenarios that can be analysed. Numerical simulation methods can substitute physical tests by virtually testing barriers. Various practical configurations can be assessed, such as different impact speeds, impact angles, and site conditions. As stated in several VSB-related impact test standards, such as the new ISO 22343, soil conditions can significantly influence the performance of VSBs. Nevertheless, test standards frequently lack comprehensive guidance on how to deal with soil conditions. However, it is crucial to be aware of the mechanical properties of the soil, especially when dealing with numerical simulations of the interaction between the soil and the embedded barrier foundation. This report investigates the relationship between soil conditions and the performance, underscores the importance of considering soil conditions during the VSB design, highlights the need for consistent soil assessments, and provides guidance for enhancing security in urban areas. While numerical vehicle models of specific vehicle categories are already available and can be utilized, the focus is on a methodology for numerically modelling the surrounding soil domain. The critical role of the soil domain dimensions, the influence of the finite element size in the meshed soil domain, and the soil modelling strategies are investigated. The basics on the characteristics of coarse-grained soil is presented, which are usually used in traffic infrastructure such as roadways or walkways. Sensitivity studies further highlight the role of soil material properties, such as the angle of internal friction, the angle of dilatancy, the cohesion and the Young's modulus on the VSB response. Furthermore, the influence of impacting vehicle’s type on the VSB response is demonstrated, i.e., EU-truck type versus US-truck type. While the primarily focus is on the soil conditions, the report also addresses the vital role of the surface courses of traffic infrastructure, such as asphalt surface courses. Furthermore, it discusses the interaction between the VSB-foundation and underground infrastructure, encompassing elements like sewers and gas networks. This report contributes towards the goal of further using numerical simulations to assess the performance of vehicle security barriers. It demonstrates that numerical simulations can be a useful tool for studying variations in the soil type, drawing inspiration from practical applications, e.g., due to different traffic infrastructure constructions. The findings emphasize the need for soil-focused guidelines for the testing and installation of vehicle security barriers.JRC.E.3 - Safety and Security of Building