Protective Structures Research Papers - Academia.edu (original) (raw)

Concrete is basic construction material used for many kind of structure. However, in the majority essential structures such as nuclear plants, Power plants, Weapon Industries, weapons storage places, water retaining structures like dams, & etc., concrete structures have to be designed as self-protective structure endow with defense against any disaster or consciously engendered unpleasant incidents such as terrorist attack, war, missile attacked by war jets, and dynamic loading, dynamic local impact damage and global damage generated by kinetic missiles (steel rods, steel pipes, turbine blades, etc.). This study inquisitively is paying attention on verdict the numerical simulation on the behavior of concrete structures against local impact effect generated by hard missile. The fallout conquer from this study can be used for making design counsel and design procedures for seminal the dynamic retort of the target to foil local and global impact damage. This paper only endow with the appraisal of prior analytical model investigation connected with our study.

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- Civil Engineering, Structural Engineering, Concrete, Structural Dynamics

History has demonstrated that buildings designed to conventional design codes can lack the robustness necessary to withstand localised damage, partial or even complete collapse. This variable performance has led governmental organisations to seek ways of ensuring all buildings of significant size possess a minimum level of robustness. The research community has responded by advancing understanding of how structures behave when subjected to localised damage. Regulations and design recommendations have been developed to help ensure more consistent resilience in all framed buildings of significant size, and rigorous design approaches have been specified for buildings deemed potentially vulnerable to extreme loading events. This paper summarises some of the more important progressive collapse events, to identify key attributes that lead to vulnerability to collapse. Current procedures and guidelines for ensuring a minimum level of performance are reviewed and modelling methods for structures subjected to localised damage are described. These include increasingly sophisticated progressive collapse analysis procedures, including linear static and non-linear static analysis, as well as non-linear static pushover and linear dynamic methods. Finally, fully non-linear dynamic methods are considered. Building connections potentially represent the most vulnerable structural elements in steel-framed buildings; their failure can lead to progressive collapses. Steel connections also present difficulties with respect to frame modelling and this paper highlights benefits and drawbacks of some modelling procedures with respect to their treatment of connections.

- by IJAEM Journal
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- Civil Engineering, Structural Engineering, FEM, Protective Structures
- by IJAEM Journal
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- FEM, Protective Structures, Passive Safety

In this article the author mentioned the various aspects of protective shelter that was using for protecting the archaeological areas against environmental factors and also the applications for presenting this areas to community. These applications are the contemporary additions to the areas. Sometimes there is a need to protective shelter for protecting the architectural remains that was exposing during archaeological excavations from environmental factors, after making the necessary conservation efforts. Protective shelter offers solutions to negative environmental factors and also develop a series of solutions against new climatic conditions occurring within the roof structure as well as drainage system should be carried out around the situation. In other words this system solved problems of protection while it creates new problems. Thus, it is needed very carefully planned before it realized. There is also needed to taking into account of balance between the presentation and the architectural field and organizing the best method to emphasizing the importance of field that gives a new dimension to the field. For this reason the field should be designed with a balance between the field and its main subject the archaeological remains. These implementations for protecting and presenting also require an interdisciplinary study. They can be reached in a sustainable system when the archaeological sites taking into account of “Management Plan”. The principles on the subject were determined in national and international level.

Equivalency is often used to enable calculations of overpressures and impulses for explosives other than TNT. Equivalent mass factors are available for far field detonations but none are available for near field detonations. These reported factors are associated with incident overpressure and impulse and assumed appropriate for reflected overpressure and impulse. Numerical studies of TNT-equivalent mass factors for four high explosives (PETN, Composition B, Pentolite and Tetryl) for incident and normally reflected peak overpressure and impulse are presented for a wide range of scaled distance 0.06 ≤ Z ≤ 40 m/kg 1/3. Emphasis is placed on near-field detonations for which no reliable factors are currently available.

- by David Cormie
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- Civil Engineering, Protective Structures

Concrete is basic construction material used for almost all kind of structure. However, in the majority essential structures such as nuclear plants, Power plants, Weapon Industries, weapons storage places, water retaining structures like dams, highways barriers, bridges, & etc., concrete structures have to be designed as self-protective structure which can afford any disaster or consciously engendered unpleasant incidents such as incident occurs in nuclear plants, incident in any essential industry, terrorist attack, Natural disasters like tsunami and etc missile attack, and local impact damage generated by kinetic missiles dynamic loading (steel rods, steel pipes, turbine blades, etc.). This paper inquisitively is paying attention on verdict of the recent development in formulating analytical behavior of concrete and reinforced concrete structures against local impact effect generated by hard missile with and without the influence of dimensional analysis based on dominant non-dimensional parameters, various nose shape factors at normal and certain inclined oblique angles. The paper comprises the analytical models and methods for predicting penetration, and perforation of concrete and reinforced concrete. The fallout conquer from this study can be used for making design counsel and design procedures for seminal the dynamic retort of the concrete targets to foil local impact damage.

- by Dr Qadir Bux Imran Latif
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- Civil Engineering, Structural Engineering, Concrete, Structural Dynamics

Standards, guidelines, manuals, and researches refer mainly to the required protection of a nuclear power plant (NPP) containment structure (where the reactor's vessel is located) against different internal and external extreme events. However, there is no consideration regarding the man-made extreme event of external explosion resulting from air bomb or cruise missile. A novel integrated blast resistance model (IBRM) of NPP's reinforced concrete (RC) auxiliary facilities due to an external above ground explosion based on two components is suggested. The first is structural dynamic response analysis to the positive phase of an external explosion based on the single degree-of-freedom (SDOF) method combined with spalling and breaching empirical correlations. The second is in-structure shock analysis, resulting from direct-induced ground shock and air-induced ground shock. As a case study, the resistance of Westinghouse commercial NPP AP1000 control room, including a representative equipment, to an external above ground blast loading of Scud B-100 missile at various standoff distances ranging from 250 m (far range) till contact, was analyzed. The structure's damage level is based on its front wall supports' angle of rotation and the ductility ratio (dynamic versus elastic mid-span displacement ratio). Due to the lack of specific structural damage demands and equipment's dynamic capacities, common protective structures standards and manuals are used while requiring that no spalling or breaching shall occur in the control room while it remains in the elastic regime. The engineering systems and equipments' spectral motions should be less than their capacity. The integrated blast resistance model (IBRM) of the structure and its equipment may be used in wider researches concerning other NPP's auxiliary facilities and systems based upon their specifications.

- by I. Brandys
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- Protective Structures

In-structure shock of underground structures subjected to ground shocks is investigated, both theoretically and experimentally. In the theoretical prediction, the ground shock is simplified to a triangular pulse with a rise time. It is found that the acceleration time history of the structure when the rise time of the ground shock is considered is significantly different from that when it is neglected. A small scale test is designed and conducted to validate the theoretical prediction. The comparison of the measured and predicted acceleration time histories suggests that the theoretical prediction with ground shock rise time considered is more reasonable. Further, shock response spectra for the equipment attached to the underground structure are established and a case study indicates that in-structure shock level of the devices predicted by the model with ground shock rise time is higher than that predicted without consideration of the ground shock rise time. It is shown that the present assessment of in-structure shock is reasonably accurate and it can be used for a preliminary design of underground structures where in-structure shock is concerned.

- by Hongyuan Zhou
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- Structural Dynamics, Protective Structures, Blast Mitigation, In-structure Shock
- by Mukesh Kumar and +1
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- Interaction Design, Soil Mechanics, Soil Dynamics, Soil-Structure Interaction
- by Alireza Farhidzadeh and +1
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- Mechanical Engineering, Civil Engineering, Experimental Mechanics, Protective Structures
- by Gabi Ben-dor and +1
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- Civil Engineering, Protective Structures
- by Andrew S Whittaker
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- Civil Engineering, Protective Structures

Various composite products are made of polyester polymers reinforced with synthetic fibers. In this research work, series of Triaxial fabrics are prepared using Polyester, Kevlar 29 and Vetran. The effect of material type on quasi-static puncture resistance is studied comparatively. The failure mode of the fabrics is analyzed. Findings indicate that the material type affects the quasi-static puncture resistance property of Triaxial fabrics. The contact pressure of fabric-probe represents the main resistance during the quasi-static puncture processes leading to the breakage of the fibers under penetration of the probe caused by tensile stress. The puncture resistance of the triaxial fabric/polyester composite was enhanced through the adding of a certain percentage of glass nanoparticles to the polyester polymer. The polyester/glass Nanoparticle matrix show better puncture resistance than ordinary polyester polymer matrix. The analysis of the results of the punching stress and the punching energy of the triaxial fabric/polyester/glass Nanoparticles composite is enhanced due to the application of the hybrid polyester/glass Nanoparticles using 2.8% glass particle volume fraction.

The response of a blast mitigation cladding consisting of a face sheet and metal foam core subjected to a close-range blast is predicted. While the cladding is sufficiently wide compared to the standoff distance between the explosion center and the cladding, the boundary of the blast induced bulge is released. The face sheet is considered as a rigid perfectly plastic membrane as the deformation of the sheet always exceeds half its thickness. A procedure predicting the depth and extent of the bulge is proposed with energy method. Subsequently, the minimum thickness of the foam layer is calculated based on the bulge depth. This design-oriented approach, in a ready-to-use manner, can be straightforwardly applied, facilitating the preliminary design of blast mitigation claddings with metal foam core.

- by Hongyuan Zhou
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- Metal Foams, Protective Structures, Blast Mitigation

The protection of buildings and structures against blast loads has long been of significance and attracted continued attention of research and industrial communities. Rather than strengthening the structures themselves, possible application of attaching cellular materials and structures to the exterior of structures to alleviate load on them is reviewed. First the properties of cellular solids under typical loading conditions, i.e., quasi-static compression, low to mediate rate compression, as well as high velocity compression, are briefed. Then the dynamic behavior of the composite structures containing cellular materials subjected to blast loads is introduced. The emphasis is placed on the dynamic response of blast mitigation cladding and their protection efficiency. Amongst, the analysis methods in terms of energy absorption and impulse transfer are surveyed and the fundamental problem of whether attaching cladding with cellular solid core to the exterior of protected structure can effectively mitigate blast load is discussed. Throughout the review, merits and drawbacks of the existing models and applications are examined and discussed. Some possible future directions on structure blast mitigation with cellular solid cladding are presented, inclusive of blast mitigation cladding with gradient cellular solid cores of specific density variations, active protection cladding rather than the traditionally studied passive protection methods.

- by Hongyuan Zhou
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- Protective Structures, Blast Mitigation

Concrete is basic construction material used for any kind of structure. However, in most vital and local structures such as nuclear plants, Power plants, Weapon Industries, weapons storage places, water retaining structures like dams, and also local industries, & etc., concrete structures have to be designed as defensive structures to provide protection against any accidents or knowingly generated incidents such as dynamic loading, dynamic local impact damage and global damage generated by kinetic missiles (steel rods, steel pipes, turbine blades, etc.). The impacting missile (projectile) can be classified as ‘Hard’ and ‘Soft’ in nature, depending upon the implication of its deformation with respect to the deformation of target. ‘Hard’ missile impact can generate both local impact damage and also overall dynamic global damage of concrete structure. This paper only provides the review of previous empirical studies related to our study and can be used for making design recommendation and design procedures for determining the dynamic response of the target to prevent local and impact damage.

- by Dr Qadir Bux Imran Latif
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- Civil Engineering, Structural Engineering, Concrete, Structural Dynamics

Concrete is basic construction material used for most structures. However, the vital structures have to be designed as self-protective such as nuclear plants, power plants, weapon industries, weapons storage places, water retaining structures, highway structures, & etc. These structures should have to be offer self shield against any natural disaster tragedy incidents and intentionally produced horrible incidents such as dynamic loading, incident occurs in nuclear plants, terrorist attack, missile attack, tsunami and etc. In modern science, the impact energies are crucial way to study the local impact effects on concrete structures together with the influence of relative target thickness (H/d). This study is focused on minimum required kinetic energy for perforation of the concrete structures generated by flat nose hard missile in terms of relative target thickness (H/d), by using curve fitting empirical study with the implementation of dimensional analysis of non-dimensional numbers. For verification, the proposed developed empirical formula was well compared with other established empirical formulae such as NDRC, UMIST and Semi Empirical formulae and it is expected that the outcome of the proposed formulae can be applied in design recommendations and design procedures for determining the dynamic reaction of the concrete target to foil perforation of flat nose hard missile.

- by Dr Qadir Bux Imran Latif
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- Civil Engineering, Structural Engineering, Concrete, Structural Dynamics

A novel woodpecker's head-inspired sandwich beam, comprising carbon fiber laminated skins with rubber and aluminum honeycomb cores, was developed for low-velocity impact behavior improvement. A comparative study against conventional sandwich beam was performed employing three impact energy levels (7.28J, 9.74J, 12.63J) by means of experimental and numerical methods. In all cases, bio-inspired beams were consistently superior to those conventional, with low developed stress, deformation, and damage area while carrying higher maximum impact force. Even with a low added mass, the impact resistance efficiencies of the bio-inspired beams were 2.7 – 5.7 times greater than those of conventional configuration, thus exhibiting an improved impact performance of the developed bio-inspired beam useful for future protection strategy.

- by Tuan Ngo
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- Civil Engineering, Protective Structures

Detonations of nitromethane spherical charges have been carried out to study close-in blast loading of steel plates and the effectiveness of several protective solutions. Three types of bare steel plates, namely mild steel, high-strength steel, and stainless steel were subjected to explosive blast loading. Steel plates of the same type with polyurea coating and composite covers were also subjected to localized blast loading. During an explosive field trial, the blast pressures and displacements of steel plates were measured. Additionally, loading of steel plates by the impinging detonation products was captured by high-speed video recordings. This experimental program has produced results which can be used to calibrate numerical models and to refine the simplified models for predicting blast loads and response of structural elements due to close-in detonations. The effectiveness of polyurea coating for enhancing blast protection of steel plated structures is discussed. The engineering-level model for predicting the blast impact impulse of the detonation gases from the charges in close proximity from the target is introduced and validated using the experimental results obtained during the course of the explosive trials.

In-structure shock poses a great threat to equipment and devices in underground protective structures, preventing them from accomplishing designed tasks. Unlike traditional mitigation methods such as backfilling soft soil or sand around the buried structures and adding shock-isolation cushions to the equipment, a new structural design of underground structures are proposed by constructing an isolation slab, to which the equipment is attached. The excitation mechanism for the equipment attached to the slab is altered from the combination of flexural deflection and rigid body motion of the traditional floor to the response of the isolation slab. Analysis indicates that vertical shock level experienced by the equipment is effectively reduced. The in-structure shock mitigation approach proposed in the present study provides a supplement to the existing shock mitigation methods for underground structures.

- by Hongyuan Zhou
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- Structural Dynamics, Protective Structures, Shock Mitigation

This paper describes a conservative analytical approach for quantification of glazing hazard in terms of number of casualties among building occupiers from flying glass fragments produced by shattered windows due to external explosive blast. Three main stages are discussed in the proposed analytical approach: modelling nonlinear transient–dynamic response of monolithic windows subjected to conventional explosions, conservative estimation of glass fragment trajectories influenced by additional aerodynamic forces due to vented blast pressures and estimation of casualties. Four injury severity levels are considered, ranging from minor cuts and bruises to multiple serious injuries with significant blood loss. The total kinetic energy of fragments at impact on occupiers is estimated and used to predict the severity level of injuries, with calculation based on available injury data from archive events. Comparison studies presented in this paper highlight the lack of robustness of existing methods towards quantification of glazing hazard due to explosive blasts. The proposed analytical method will be of direct importance to both engineers and practitioners involved with planning glazing retrofits for existing buildings and identifying cost-effective combinations of protection measures for new buildings.

- by Gayan Wijesundara
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- Structural Dynamics, Aerodynamics, Protective Structures, Damage Assessment

A numerical approach is carried out to investigate the energy absorption efficiency of density graded aluminium foam. Effects of blast load impact velocity, loading duration and sample thickness on the input energy density and output energy density of the graded foam are investigated. The stochastic meso-scale aluminium foam structure is generated by adopting a 2D Voronoi technique and the commercial software ANSYS/LS-DYNA is used for the FE modelling. Parametric study shows that the density graded aluminium foam is effective in improving energy absorption capability while keeping a lower stress transmitted to the substrate or the protected structure if it is properly designed.

- by Hongyuan Zhou
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- Protective Structures, Metallic Foams, Blast Mitigation

Türkiye'de Arkeolojik alanlarda, bilimsel kazı çalışmalarıyla gün yüzüne çıkarılan kalıntıların korunması ve sergilenmesi amacıyla pek çok koruma örtüsü inşa edilmiştir. Söz konusu örtüler, metal veya ahşap destekler üzerinde saç, sentetik branda gibi daha basit uygulamalardan, tüm alanı kaplayan ve destek sayısı azaltılmış uzay çatı sistemleri ile mimari kalıntı ve eser grubunu tümünü kapsayacak ileri tasarımlara kadar çeşitlilik göstermektedir. Uygulandıkları alanlara göre çeşitlikleriyle de dikkat çeken koruma örtülerinin tasarımlarında da çok sayıda kriter belirleyici olmaktadır. Bu çalışmada, koruma örtülerinin tasarım kriterleri, çağdaş koruma ilkelerinin belirlendiği uluslararası tüzük ve yönetmeliklerde yer alan hükümler doğrultusunda, arkeolojik alanlarda uygulanan seçilmiş bazı örneklerdeki gözlem ve incelemelerle belirlenmeye çalışılmıştır Many protective structures have been built in order to protect and display the remains uncovered by archaeological excavations in Turkey. The protective structure designs range from simpler applications such as sheet metal on metal or wooden supports, synthetic tarpaulin to advanced designs such as space truss structure that cover the entire area architectural remains and group of archeological artifacts. A number of criteria are also determinative in the design of the protective structure, which draws attention with their diversity according to the areas they are applied. In this study, protective structure design criteria have been tried to be determined by observations and examinations in selected examples applied in archaeological areas in line with the provisions of international regulations and codes which include modern protection principles.

- by Yaşar S E L Ç U K ŞENER and +1
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- Conservation, Cultural Heritage Conservation, Architectural Conservation, Protective Structures

- by Magdi El Messiry
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- Fabrics, Protective Structures, Knitted Fabrics

This paper details the development of an engineering assessment procedure for reinforced concrete column failure when subject to coupled uplift and shear forces typically induced by vented internal building detonations. This is based on a set of comprehensive parametric studies conducted using advanced Computational Fluid Dynamics and transient structural dynamic modelling techniques. These analyses are ratified and underwritten by independent verification using archive experimental data and alternative advanced numerical simulations. Results from the parametric studies are analysed using a nonlinear curve fitting technique to develop a set of assessment charts quantifying the extent of overall damage and residual axial column capacity when subject to internal building detonations. Application of the assessment procedure is demonstrated and the effect of compressive strength of concrete, column orientation and slenderness on damage behaviour and residual axial capacity are discussed. The developed assessment method will be of direct relevance to both practitioners and engineers involved with the protective design of buildings.

Extreme loads can have devastating effects on civilian structures since these buildings are not designed to have to withstand extreme events. Typical buildings and other critical infrastructure are particularly prone to external man-made attacks. This study focuses on probabilistic analyses, and investigates the probability of failure of a precast concrete wall subjected to blast loads. The wall under investigation is a non-load bearing precast concrete panel used as exterior cladding for buildings. From the blast design point of view, these walls must protect people and equipment from external detonations. The aim of the paper is to compute both the fragility curves of typical precast concrete cladding subjected to blast loads, and the failure probability of the cladding, considering a detonation of a vehicle borne improvised explosive device (VBIED). To this aim non-linear dynamic analyses are carried out by the widely adopted equivalent non-linear SDOF method for the precast concrete panel. The fragility curves and the failure probability of the precast concrete cladding wall are computed using Monte Carlo simulations.

Underground structures are sometimes threatened by ground shocks induced by subsurface detonations. One possible method to mitigate the subsurface blasts is proposed by attaching a cladding consisting of a face sheet and cellular solid core to the exterior of the structure, where the cellular core is foam made from relatively strong materials such as metal or concrete, rather than typical geofoam made from polymer. A simplified model is established to distinguish three scenarios to delineate the dynamic behavior of a foam cladding subjected to a ground shock, by comparing the velocity time histories of the face sheet and the surrounding soil, where the foam crushing velocity is not high and the foam is densified uniformly. Further, the governing equations for possible high velocity foam crushing are established, with progressive collapse as foam crushing mode when alleviating subsurface blasts.

- by Hongyuan Zhou
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- Protective Structures, Blast Mitigation, Ground Shock

In order to prevent the deterioration of immovable architectural artefacts unearthed in archaeological sites, it is observed that protective structures are applied. A considerable number of applications for both temporary and permanent protective structures have significant differences in terms of design, scale and material whereas the visitor impression is not particularly taken into account. In this study protective structures are classified according to their practice in the archaeological sites and a survey-based evaluation is revealed in which visitors indicate responses for their impressions. Furthermore, it has been stated that even though there are principles for new structures provisioned by international charters and regulations, there are not only professional approaches but also visitor impressions and experiences that should be considered as design criteria. In conclusion, the research points out the importance of engagement of visitors in the design process regarding the site effect of the protective structures.

- by Martin Larcher
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- Civil Engineering, Strain Rate, Protective Structures
- by P V KRISHNAKANT
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- Civil Engineering, Structural Engineering, Concrete, Structural Dynamics
- by David Cormie
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- Civil Engineering, Protective Structures

Great demand exists for more efficient design to protect delicate and serious structures such as nuclear plants, Power plants, Weapon Industries, weapons storage places, water retaining structures, & etc, against impact of kinetic missiles generated both accidentally and deliberately such as dynamic loading, incident occurs in nuclear plants, terrorist attack, Natural disasters like tsunami and etc., in various impact and blast scenarios for both civilian and military activities. In many cases, projectiles can be treated as rigid bodies when their damage and erosion are not severe. Due to the intricacy of the local impact damages, investigations are generally based on experimental data. Conclusions of the experimental observations are then used to guide engineering models. Local damages studies normally fall into three categories, i.e. empirical formulae based on data fitting, idealised analytical models based on physic laws and numerical simulations based on computational mechanics and material models. In the present study, 2D asymmetrical numerical simulation have done on concrete slab against the impact of ogive nose hard missile of 26.90mm and 76.20mm diameter with CRH ratio 2.0 and 6.0 respectively, for penetration by using Concrete Damaged Plasticity Model, and ABAQUS/Explicit dynamic analysis in ABAQUS. It is found that the strains/stresses are induced in the concrete slab and a very nicely propagation of the stresses inside the concrete slab in the form of waves, which is a clear indication for vibrations of the concrete. The lack of failure criterion in concrete damaged plasticity model does not allow the removal of elements during the analyses. This means that spalling, scabbing, and perforation cannot be modelled with the Concrete Damage Plasticity Model. The penetration depth results shows that the deeper penetration requires higher critical impact kinetic energies, and comparison shows the simulation results are more accurate than other formulae predicted results.

- by Dr Qadir Bux Imran Latif
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- Civil Engineering, Structural Engineering, Concrete, Structural Dynamics
- by Tuan Ngo
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- Protective Structures

- by Andrew S Whittaker
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- Civil Engineering, Protective Structures
- by Mark Stewart
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- Civil Engineering, Decision Support Systems, Risk Management, Risk assessment
- by Kazunori Fujikake
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- Civil Engineering, Protective Structures
- by Nawawi Chouw
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- Civil Engineering, Protective Structures

This paper details the development of an engineering assessment procedure for reinforced concrete column failure due to time-variant coupled uplift forces and lateral blast pressures characteristic of internal building detonations. This is primarily based on ratified high-resolution computational fluid dynamics simulations and advanced transient structural dynamic modelling techniques. A set of comprehensive parametric studies are conducted and results are analyzed using a non-linear curve fitting technique to develop assessment charts quantifying the extent of overall damage and residual axial column capacity following internal blast actions.

When an underground structure is subjected to a subsurface explosion, an in-structure shock occurs. The in-structure shock can be a major cause of disruption and even damage to the instruments and equipment contained in the structure if the detonation is relatively distant. For this reason, an appropriate analysis and prediction of explosion-induced in-structure shock is an important topic in the area of protective design of underground structures. In this paper, a detailed analysis is conducted on a representative buried structural element subjected to soil-transmitted blast. The soil-structure interactions are considered by introducing an interfacial damping between the structural element and the surrounding soil. Two phases of the structural response to the blast load, i.e., a blast loading phase and a free-vibration phase, are analyzed. Based on the analytically derived time histories of the structural response, which represent the in-structure shock, the response spectra concerning the equipment (sub-structures) attached to the main structure are constructed. Besides providing a theoretical approach for the evaluation of the in-structure shock and its subsequent effects, the present analysis is supplementary to the relevant provisions in TM5-855-1 and TM5-1300, in which only rough predictions of in-structure shock for buried structures are specified.

- by Hongyuan Zhou
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- Structural Dynamics, Protective Structures

Penetration is the basic element of designing protective concrete structure against the local impact of hard missile. Vital structures such as nuclear plants, power plants, weapon industries, weapons storage places, water retaining structures like dams, local industries, highway barriers & etc., have to be designed as self-protective structures in order to resist kinetic impact, natural disaster, consciously engendered unpleasant incidents, or/and against accidentally occur incidents in nuclear plants, local industries etc., (generated by dynamic loading and kinetic missiles and etc.). Critical impact energy is the dominant cause of local damage in concrete structures. Therefore, it is vital to study critical impact energy that causes penetration. An analytical model is developed to predict the required critical impact energy for maximum penetration without rear effects in concrete slabs when it is impacted with ogive nose hard projectile. The newly developed analytical model is examined for CRH =2.0 and CRH=4.25. It was found that the predicted results from analytical model are in close relation with experimental data with less than (8%) and (17%) error in case of CRH =2.0 and CRH=4.25. Furthermore, a nose shape factor (Ni) with introduction of empirical frictional factor (Nf) in Chen and Li nose shape (N*) is proposed. It was found that the predicted results from analytical model with nose shape (Ni) are in close relation with experimental data with less than (17%) error in all cases as compared to predicted results with traditional Li and Chen nose shape (N*). In general, the analytical model generates encouraging prediction which is consistent and follows a general trend of experimental results. Therefore, it is suggested that the proposed analytical model is conservative.

- by Dr Qadir Bux Imran Latif
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- Civil Engineering, Structural Engineering, Concrete, Structural Dynamics

Background and Problem: Concrete is basic construction material used for structures. However, in case of the vital structures such as nuclear plants, power plants, weapon industries, weapons storage places, water retaining structures like dams, & etc., have to be designed as self-protective structures, which provides protection against local impact effects of hard missile against disastrous incidents or intentionally produced horrible incidents such as incident occurs in nuclear plants, terrorist attack, war, tsunami and etc. Methodology: The local impact effects can be studied by using dimensional analysis of non dimensional numbers in terms of the critical impact energies. The way in which the kinetic energy is distributed through the concrete target is also noteworthy in determining its response. In this paper, the influence of the relative target thickness (H/d) on those critical impact energies, at which scabbing occurs are explored. A dimensional analysis was conducted to identify influential non-dimensional numbers, which were subsequently employed in the development of proposed empirical formula relevant to required critical impact kinetic energy for scabbing by flat nose hard missiles. Results and Verification: The study is focused on judgment of minimum required kinetic energy for scabbing generated by flat nosed hard missile on the concrete structures. The results of proposed developed empirical formula are compared with other well established empirical and semi-empirical formulae, in order to examine the effects of (H/d) on the critical impact energy for scabbing failure. Conclusion: It is expected that the overcome from proposed developed empirical formula can be used for making design recommendations and design procedures for determining the dynamic reaction of the target to frustrate scabbing in terms of kinetic energy

- by Dr Qadir Bux Imran Latif
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- Civil Engineering, Structural Engineering, Concrete, Structural Dynamics

Penetration is one of the elements in design consideration effects of the local impact damage phenomena. It has to be investigated for designing protective concrete structures in order to resist kinetic impact by hard projectile. Kinetic energy is the dominant cause of damage in moving accidents. When hard projectile collides with concrete target, it is the kinetic energy of the projectile that makes concrete target to deform. Therefore, it is vital to study critical impact kinetic energy that causes penetration (local impact phenomena). A two dimension (2D) asymmetrical numerical simulation analysis has been conducted on ABAQUS software using dynamic explicit analysis function with constitutive model of Concrete Damaged Plasticity. The simulation was to determine the critical impact energy of ogive nose hard projectile which causes maximum penetration in to the concrete structures during local impact. It was found that the simulation results are in close relation with experimental data with less than 7% error in all cases. The limitation of Concrete damaged plasticity model is it contains no failure criteria. The effects of diameter and CRH ratio of ogive nose hard projectile on critical impact energy were also analysed. It is found that bigger diameter of ogive nose projectiles requires more critical impact energy for maximum penetration of concrete target as compared to the smaller diameter of ogive nose. For small CRH ratio of hard missile, it requires higher critical impact energy for maximum penetration of concrete target.

- by Vasilis Karlos
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- Engineering, Civil Engineering, Protective Structures

In the present study, a comparative assessment on the performance of conventional and advanced tunnel lining materials subjected to blast loading is done using a three-dimensional non-linear finite element analysis procedure. The conventional tunnel lining materials analyzed herein are plain concrete, steel, reinforced cement concrete, and steel fiber–reinforced concrete. The advanced tunnel lining materials analyzed herein are dytherm, polyurethane, and aluminum syntactic foam sandwich panels with steel–foam–steel composites. The pressure generated by 10 kg Trinitrotoluene (TNT) is applied to each element on the inner wall of the tunnel which has an effect equal to the scaled distance Z = 1.16 m/kg1/3. Analyses are conducted by varying the thickness of lining materials for a tunnel built in rock domain. The response of the tunnel lining materials, for example, deformation, stresses, and strains generated at different interfaces, is compared with each other to assess the best suitab...

- by Vasant Matsagar
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- Civil Engineering, Protective Structures