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‣ Blast analysis of enclosure masonry walls using homogenization approaches

Milani, G.; Lourenço, Paulo B.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
515.25207%
A simple rigid-plastic homogenization model for the analysis of enclosure masonry walls sub- jected to blast loads is presented. The model is characterized by a few material parameters, is numerically inexpensive and very stable, and allows full parametric studies of entire walls subject to blast pressures. With the aim of considering the actual brickwork strength along vertical and horizontal axes, masonry out-of-plane anisotropic failure surfaces are obtained by means of a compatible homogenized limit analysis approach. In the model, a 3D system of rigid infinitely strong bricks connected by joints reduced to interfaces is identified with a 2D Kirchhoff-Love plate. For the joints, which obey an associated flow rule, aMohr-Coulomb fail- ure criterion with a tension cutoff and a linearized elliptic compressive cap is considered. In this way, the macroscopic masonry failure surface is obtained as a function of the macroscopic bending, torque, and in-plane forces by means of a linear programming problem in which the internal power dissipated is minimized. Triangular Kirchhoff-Love elements with linear in- terpolation of the displacements field and constant moment within each element are used at a structural level. In this framework, a simple quadratic programming problem is obtained to analyze entire walls subjected to blast loads. The multiscale strategy presented is adopted to predict the behavior of a rectangular wall supported on three sides (left...

‣ Security evaluation and design of structures subjected to blast loading

Pereira, João Miguel
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Tese de Doutorado
Publicado em 27/06/2014 Português
Relevância na Pesquisa
495.1003%
Tese de doutoramento em Engenharia Civil; The work presented in this thesis was developed at the Department of Civil Engineering of University of Minho. This work involves experimental and numerical campaigns and intends to give a contribution for a better understanding of the effect of explosions. Blast loading is a subject of much actuality and considerable lack of expertise. Europe has never been so rich and safe, where the violent years of the first half of the 20th century lead to an unprecedented period of peace and stability. Despite the terrorist decades, e.g. connected to ETA and IRA in Europe, the attacks of Madrid (2004), London (2005) and worldwide (New York, Oklahoma, Mumbai) had a major psychological effect in the societies. Clearly, the understanding about the effect of blast loading in structures and their subsystems saves lives and reduces damage in buildings. The Buncefield explosion (2005) resulted in tremendous damage to the outlying area and huge fires involving 23 large oil fuel tanks. Experimental and finite element analyses are carried out for the static and dynamic response of lightweight metal boxes that are similar to the steel junction boxes on the site of this explosion. During the Buncefield Explosion Mechanism Phase I research...

‣ Effect of blast loading on CFRP-Retrofitted RC columns - a numerical study

Elsanadedy,H.M.; Almusallam,T.H.; Abbas,H.; Al-Salloum,Y.A.; Alsayed,S.H.
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 Português
Relevância na Pesquisa
598.2362%
This study aims to investigate the effect of blast loads generated as a result of explosive charges on the existing exterior RC circular columns of a typical building in the city of Riyadh. A procedure has been developed for evaluating the dynamic characteristics of the circular column with and without retrofitting. A wide range of parametric studies have been performed as part of this investigation to examine the effects of stand-off distance, charge weight and the presence of CFRP retrofitting on the level of damage to the RC column. The nonlinear finite element analysis was carried out using LS-DYNA software with explicit time integration algorithms. Different charge weights of 100, 200, 500 and 1000 kg equivalent weight of TNT at stand-off distances of 1, 4 and 15 m were considered. Results described in this paper indicate that CFRP strengthening could be an effective solution to limit the damage caused by moderate explosions. The stand-off distance was found to play a very important role in mitigating the adverse effects of a blast. The results also indicate that the maximum lateral deflection experienced by the column decreased exponentially with the increase in the stand-off distance and also decreased for the columns strengthened with CFRP...

‣ Blast resistance assessment of structures: explicit finite element simulations and fragility analyses

OLMATI, PIERLUIGI
Fonte: La Sapienza Universidade de Roma Publicador: La Sapienza Universidade de Roma
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
395.86984%
A failure of the security system of a community leads to a socio-economic instability and consequently to the decline of the community. Nowadays like in the past, a protective design against man-made attacks is important, especially considering that the Free World is constantly prone to destabilization by terrorism. A protective construction should principally guarantee the maximum reasonable survivability of the occupants. If the prevention strategies of defense fail (e.g. intelligence and police activities), the design for blast offers the only possibility to limit the consequences of an explosion. The resistance of a generic structure subjected to a blast load is measured in terms of collapse resistance, defined as the exceeding of a performance limit. The collapse resistance can be assessed directly by applying the blast demand to the structure (un-decomposed approach) or by decomposing the collapse resistance (decomposed approach) in three components: the hazard mitigation, the local resistance, and the global resistance. In this Thesis the decomposed approach is preferred and methods for a quantitative assessment of the collapse resistance’s components are proposed and applied to case-study structures. Concerning the hazard mitigation...

‣ Numerical analysis of structural progressive collapse to blast loads

Hao, H.; Wu, C.; Li, Z.; Abdullah, A.
Fonte: Tianjin University; China Publicador: Tianjin University; China
Tipo: Conference paper
Publicado em //2006 Português
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487.67023%
After the progressive collapse of Ronan Point apartment in UK in 1968, intensive research effort had been spent on developing guidelines for design of new or strengthening the existing structures to prevent progressive collapse. However,only very few building design codes provide some rather general guidance, no detailed design requirement is given. Progressive collapse of the Alfred P. Murrah Federal building in Oklahoma City and the World Trade Centre (WTC) sparked again tremendous research interest on progressive collapse of structures. Recently,US Department of Defence (DoD) and US General Service Administration (GSA) issued guidelines for structure progressive collapse analysis. These two guidelines are most commonly used,but their accuracy is not known. This paper presents numerical analysis of progressive collapse of an example frame structure to blast loads. The DoD and GSA procedures are also used to analyse the same example structure. Numerical results are compared and discussed. The accuracy and the applicability of the two design guidelines are evaluated.; http://scholar.ilib.cn/A-tianjdxxb-e2006z1006.html; http://202.113.13.67/colleges/civil/lzx/Welcome.html

‣ Retrofitting of RC slabs against explosive loads

Wu, C.; Oehlers, D.; Xia, S.
Fonte: Tianjin University; China Publicador: Tianjin University; China
Tipo: Conference paper
Publicado em //2006 Português
Relevância na Pesquisa
419.32168%
With the increase of terrorist bomb attacks on buildings, there is a need to develop advanced retrofitting techniques to strengthen structures against blast loads. Currently, several guidelines including an Australian version for retrofitting reinforced concrete (RC) structures are available for the design of retrofitting systems against seismic and monotonic loads using steel or fibre reinforced polymer (FRP) plates that can be either adhesively bonded to the surface or near surface mounted to the concrete cover. However, none of these guidelines provide advice suitable for retrofitting structures subjected to blast loads. In this paper, numerical models are used to simulate the performance of retrofitted RC slabs subjected to blast loads. Airblast pressure distributions on the surface of the slabs estimated in a previous study are used as input in the analysis. A material damage model developed previously for concrete and an elastoplastic model for steel bars are employed in this research for modelling reinforced concrete behaviour due to explosive loads. The material models and blast loading are coded into a finite element computer program LS-DYNA3D to do the analysis.With the numerical model, parametric studies are conducted to investigate RC slabs retrofitted by either externally bonded or near-surface mounted plates or GFRP sheets subjected to blast loads. Discussion is made on the effectiveness of the retrofitting system for RC slabs against blast loads.; http://202.113.13.67/colleges/civil/lzx/Welcome.html; http://scholar.ilib.cn/A-tianjdxxb-e2006z1018.html

‣ FRP retrofitted RC slabs using finite difference model

Wu, C.; Oehlers, D.; Whittaker, A.
Fonte: Tianjin Daxue Publicador: Tianjin Daxue
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
Relevância na Pesquisa
504.2197%
Current guidelines recommend using single-degree-of-freedom(SDOF) method for dynamic analysis of reinforced concretec (RC) structures against blast loads, which is not suitable for retrofitted members. Thus, a finite difference procedure developed in another study was used to accurately and efficiently analyze the dynamic response of fibre reinforced polymer (FRP) plated members under blast loads. It can accommodate changes in the mechanical properties of a member’s cross section along its length and through its depth in each time step, making it possible to directly incorporate both strain rate effects (which will vary along the length and depth of a member) and non-uniform member loading to solve the partial differential equation of motion. The accuracy of the proposed method was validated in part using data from field blast testing. The finite difference procedure is implemented easily and enables accurate predictions of FRP-platedmember response.; Chengqing Wu, Deric John Oehlers and Andrew Whittaker; © 2008 Springer. Part of Springer Science+Business Media

‣ Mitigation of blast effects on aluminum foam protected masonry walls

Su, Y.; Wu, C.; Griffith, M.
Fonte: Tianjin Daxue Publicador: Tianjin Daxue
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
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614.0868%
Terrorist attacks using improvised explosive devices (IED) can result in unreinforced masonry (URM) wall collapse. Protecting URM wall from IED attack is very complicated. An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy. However, mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world. In this paper, numerical models are used to simulate the performance of aluminum foam protected URM walls subjected to blast loads. A distinctive model, in which mortar and brick units of masonry are discritized individually, is used to model the performance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model. The aluminum foam is modelled by a nonlinear elastoplastic material model. The material models for masonry, aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads. Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads.; Yu Su, Chengqing Wu and Mike Griffith

‣ Layered Blast Capacity Analysis of FRP Retrofitted RC Member

Wu, C.; Oehlers, D.; Day, I.
Fonte: Multi-science Publishing Co. Ltd. Publicador: Multi-science Publishing Co. Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
505.5865%
Fibre reinforced polymer (FRP) retrofitting of RC structures against blast loading is an emerging research area of major significance. Currently, several guidelines are available for the FRP retrofitting of RC structures against monotonic and seismic loads. However, no advice is provided from these guidelines for the retrofit RC structures against blast loading. This paper formulates a layered model that allows for both FRP strengthening and the consideration of strain rate effects on the blast resistant capacity of flexural structural members. The layered model is incorporated into a single degree of freedom model for dynamic analyses and it is validated with blast tests. The validated model is then used in a parametric study which investigates the changes in strength, ductility and energy absorption capacities of flexural FRP strengthened members under blast loads. It is found that the capacity of a flexural member to resist a blast load can be increased greatly with the use of compressive face plating with the ductility of the flexural member being the key factor.; Chengqing Wu, Deric John Oehlers and Ian Day

‣ Energy-controlled design of reinforced ultra-high performance fiber concrete slabs against airblast loads

Wu, C.; Oehlers, D.; Rebentrost, M.; Leach, J.
Fonte: Trans Tech Publications Publicador: Trans Tech Publications
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
397.3358%
Displacement-controlled design method is now being used by current guidelines such as TM5 and ASCE to design RC members against airblast load. If the maximum deflection of the designed member under airblast loads is less than the allowable deflection, the designed member is considered to be safe. Although the displacement-controlled design method is easy to use, it may not result in a design having maximum energy-absorption capacity against airblast loads, especially for a design of a reinforced ultra-high performance fibre concrete (RUHPFC) member which is of both high strength and high ductility, that is, high energy-absorption capacity. In this paper, a layered analysis model allowing for varying strain rates with time as well as along the depth of the member was used to calculate energy-absorption of a simple supported RUHPFC slab under airblast loads. An optimal reinforcement ratio of the slab was achieved by maximizing the energy absorption of the slab under different reinforcement ratios. The energy-controlled design method was validated by field blast tests. Using the validated design method, a designed slab with the optimal reinforcement ratio was also tested and the effectiveness of the design was demonstrated.; Chengqing Wu...

‣ Response of earthquake-resistant reinforced-concrete buildings to blast loading

Saatcioglu, M.; Ozbakkaloglu, T.; Naumoski, N.; Lloyd, A.
Fonte: Natl Research Council Canada Publicador: Natl Research Council Canada
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
516.18887%
Recent bomb attacks on buildings have raised awareness about the vulnerability of structures to blast effects. The resiliency of structures against blast-induced impulsive loads is affected by structural characteristics that are also important for seismic resistance. Deformability and continuity of structural elements, strength, stiffness, and stability of the structural framing system and resistance to progressive collapse are factors that play important roles on the survivability of buildings under both blast and seismic loads. The significance of these structural parameters on blast resistance of reinforced concrete buildings is assessed through structural analysis. Both local element performance and global structural response are considered while also assessing the progressive collapse potential. The buildings under investigation include 10-storey moment resisting frames with or without shear walls. The blast loads selected consist of different charge-weight and standoff distance combinations. The results are presented in terms of ductility and drift demands. They indicate improved performance of seismic-resistant buildings when subjected to blast loads, in terms of local column performance, overall structural response, and progressive collapse potential.; Murat Saatcioglu...

‣ Analysis of retrofitted RC beam with fixed end supports against blast loads

Wu, C.; Cheng, W.; Oehlers, D.
Fonte: Trans Tech Publications Publicador: Trans Tech Publications
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
611.56992%
Currently, there are adequate guidelines available for FRP retrofitting RC structures against static and seismic loads. However, there is still limited information on retrofitting RC structures against short-duration dynamic loading effects such as blast loading. Due to the increasing threat of terrorism in recent years, retrofitting of RC structures against blast loading is of paramount importance in structural engineering. In this paper, a dynamic model that is based on single-degree-of-freedom (SDOF) approach is developed for the analysis of the response of retrofitted fixed end supported RC slabs subjected to blast loads. A previously validated layered capacity analysis method is used to determine the yielded and ultimate blast resistant capacity of a cross-section of a RC slab which allows varying strain rates with time along the depth of the member. The corresponding deflections are determined by plastic hinge analysis. To simplify the calculation process, a tri-linear resistance-deflection function which consists of elastic, elasto-plastic and plastic region for fixed end supported RC slabs is converted to an equivalent bilinear function. This developed model can adequately predict the retrofitted members’ response to blast loading. It is then is used to conduct a parametric study to optimise the retrofitting of RC slabs subjected to blast loading by varying the quantity...

‣ Characteristics of confined blast loading in unvented structures

Hu, Y.; Wu, C.; Lukaszewicz, M.; Dragos, J.; Ren, J.; Haskett, M.
Fonte: Multi-Science Publishing Co Ltd Publicador: Multi-Science Publishing Co Ltd
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
395.86984%
Confined blast loading occurs in many scenarios and the effects of confined blast loading may result in more serious damage to buildings due to multiple shock reflections (Shi et al. 2009). However, spherical charges are assumed for all confined explosive-effects computations in modern standards for blast-resistant design such as UFC-3-340-02 (2008) and the soon-to-be published ASCE Standard for the Blast Protection of Buildings (ASCE forthcoming) without consideration of effects of charge shape on the distribution of reflected overpressure and impulse. As confinement is an aggravation factor of explosion effects, analysis and design of infrastructure under critical scenarios of confined blast loading should take the aggravation factor into consideration. This paper is to develop a numerical model for prediction of blast loads inside unvented structures as a result of variation of the charge shape, charge orientation, geometries and volumes of confined chambers. A finite element program, AUTODYN (Century Dynamics, 2003), is utilized extensively to generate a model which is capable of being calibrated with the experimental results conducted by Wu et al. (2010) in external conditions and by Zyskowski et al. (2004) in a confined small box. The calibrated AUTODYN model is then used to conduct parametric studies to analyze the effects of the variation of charge shape...

‣ Research development on protection of structures against blast loading at University of Adelaide

Wu, C.
Fonte: Institution of Engineers Australia Publicador: Institution of Engineers Australia
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
Relevância na Pesquisa
496.5132%
This paper presents a review of research into the protection of structural members against blast loading at The University of Adelaide, including experimental, analytical and numerical studies on characteristics of blast loading, blast resistance of structural members and mitigation of blasts effects on structural members using retrofitting techniques. Explosive blasts are investigated experimentally and numerically to study the distributions of peak overpressure and impulse generated from spherical charges and cylindrical charges with different orientations in unconfined and confined environments. A series of blast tests on reinforced concrete (RC) slabs, ultra-high performance concrete (UHPC) slabs, and aluminium foam protected RC slabs was conducted to investigate the performance of those slabs under blast loads. With the blast testing data numerical models including single degree of freedom model, finite difference model and final element model, have been developed and validated and those numerical models are then used to analyse the blast effects of RC, UHPC and foam protected RC slabs. Investigation of mitigation of blast effects on masonry structures is also addressed.; C Wu

‣ Derivation of normalized pressure impulse curves for flexural ultra high performance concrete slabs

Dragos, J.; Wu, C.; Haskett, M.; Oehlers, D.
Fonte: ASCE-Amer Soc Civil Engineers Publicador: ASCE-Amer Soc Civil Engineers
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
Relevância na Pesquisa
408.9157%
In previous studies, a finite-difference procedure was developed to analyze the dynamic response of simply supported normal reinforced concrete (NRC) slabs under blast loads. Ultra high performance concrete (UHPC) is a relatively new material with high strength and high deformation capacity in comparison with conventional normal strength concrete. Therefore, the finite-difference procedure for analysis of conventional reinforced concrete members against blast loads needs to be significantly adapted and extended to accommodate UHPC. In this paper, an advanced moment-rotation analysis model, employed to simulate the behavior of the plastic hinge of an UHPC member, is incorporated into the finite-difference procedure for the dynamic response analysis of reinforced UHPC slabs under blast loads. The accuracy of the finite-difference analysis model that utilized the moment-rotation analysis technique was validated using results from blast tests conducted on UHPC slabs. The validated finite-difference model was then used to generate pressure impulse (PI) curves. Parametric studies were then conducted to investigate the effects of various sectional and member properties on PI curves. Based on the simulated results, two equations were derived that can be used to normalize a PI curve. Further numerical testing of the normalization equations for UHPC members was then undertaken. The generated normalized PI curve...

‣ A numerical investigation of blast loading and clearing on small targets

Rigby, S.E.; Tyas, A.; Bennett, T.; Fay, S.D.; Clarke, S.D.; Warren, J.A.
Fonte: Multi Science Publishing Publicador: Multi Science Publishing
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Relevância na Pesquisa
491.50926%
When a blast wave strikes a finite target, diffraction of the blast wave around the free edge causes a rarefaction clearing wave to propagate along the loaded face and relieve the pressure acting at any point it passes over. For small targets, the time taken for this clearing wave to traverse the loaded face will be small in relation to the duration of loading. Previous studies have not shown what happens in the late-time stages of clearing relief, nor the mechanism by which the cleared reflected pressure decays to approach the incident pressure. Current design guidance assumes a series of interacting clearing waves propagate over the target face – this assumption is tested in this article by using numerical analysis to evaluate the blast pressure acting on small targets subjected to blast loads. It is shown that repeat propagations of the rarefaction waves do not occur and new model is proposed, based on an over-expanded region of air in front of the loaded face of the target.; Sam E. Rigby, Andrew Tyas, Terry Bennett, Stephen D. Fay, Sam D. Clarke, James A. Warren

‣ A two-step numerical method for efficient analysis of structural response to blast load

Li, J.; Hao, H.
Fonte: Multi-Science Publishing Publicador: Multi-Science Publishing
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
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Even with modern computer power, detailed numerical modeling and simulation of structure response to blast loads are still extremely expensive and sometimes prohibitive because it is very time consuming and requires huge computer memory. Often compromise has to be made between simulation efficiency and simulation accuracy. A lot of research efforts have been spent on improving the computational efficiency. Most of these researches concentrate on simplifying the structures, such as simplifying a structure to an equivalent SDOF system, use smeared reinforcement steel and concrete model, use substructure approach to only model part of the structure in detail. Although these approaches under certain conditions yield reliable predictions, each of them has its associated limitations. Recently a two-step method was developed to improve the computation and modeling efficiency of structure response to blast loads. Instead of simplifying the structure, the proposed method calculates the structural responses in two steps. The first step calculates the structural responses in the loading phase and the second calculates the free vibration responses with the velocity profile of the structure at the end of the loading phase as initial conditions. Using a reinforced concrete beam as the example...

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

KARLOS VASILEIOS; SOLOMOS George
Fonte: Publications Office of the European Union Publicador: Publications Office of the European Union
Tipo: EUR - Scientific and Technical Research Reports Formato: Online
Português
Relevância na Pesquisa
510.4047%
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 assessment

‣ THE DYNAMIC RESPONSE OF CONCRETE FILLED FRP TUBES SUBJECTED TO BLAST AND IMPACT LOADING

Qasrawi, YAZAN
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
421.11098%
Blasts and impacts are two of the severest loads a structure can experience. Blast experimenters, however, have observed that the load imparted to a circular member was lower than the predicted design load. Additionally, numerous investigations have established the superiority of concrete filled FRP tubes (CFFTs) over conventional reinforced concrete members. These observations indicated CFFTs’ potential to resist dynamic blast and impact loads. The experimental and numerical investigations presented in this thesis aimed to demonstrate the suitability of CFFTs to resist blast and impact loads, to determine the parameters that influence their behaviour under such loads, and to develop a design procedure for resisting these loads. The initial numerical investigation determined the reflected blast loading parameters experienced by a circular cross section. The experimental phase consisted of testing twelve full scale specimens, two monotonically, four under impact loading, and six under close-in blast loading. The monotonically tested specimens acted as controls for the entire program. The results of the impact testing investigation were used to develop and validate a non-linear single degree of freedom (SDOF) model. This impact phase also led to the development of relatively simple procedures for designing CFFTs under impact loading using either SDOF modeling or the conservation of energy. Analysis of the blast testing results led to the development of numerical procedures for obtaining an equivalent close-in blast loading for SDOF analysis of CFFTs and Pressure-Impulse diagrams. The use of SDOF modeling and conservation of energy in blast design were also discussed. Finally...

‣ High strain rate constitutive modeling forhistorical structures subjected to blast loading

Rafsanjani, Seyedebrahim Hashemi
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Tese de Doutorado
Publicado em 07/05/2015 Português
Relevância na Pesquisa
516.0143%
Doctoral Thesis Civil Engineering; The work presented here was accomplished at the Department of Civil Engineering of University of Minho. This work involves detailed numerical studies intended to better understand the blast response of masonry structures, develops strain dependent constitutive material plasticity model for masonry, and addresses iso-damage curves for typical masonry infill walls in Portugal under blast with different loading conditions, which can be adopted for practical use in the case of enclosures. A bomb explosion near a building, in addition to a great deal of casualties and losses, can cause serious effects on the building itself, such as noticeable damage on internal and external frames, collapsing walls or shutting down of critical life safety systems. Until Oklahoma City bombing in 1995, studies dealing with the blast behavior of structures were a field of limited interest in the civil engineering community. After this terrorist attack, a great deal of effort has been done to better understand the blast response of the structures and devise solutions to reduce destructive damages and casualties due to such devastative loads. Moreover, the studies on the influence of the high strain rate on mechanical characteristics of construction materials such as steel and concrete have been carried out intensively. Unfortunately...