Blast Resistant Structures Research Articles

Effect on high rise structure expose to blast load

The impression of blast load on building is very important things to consider in a design process. A bomb detonation within structures or straightaway the building can drive damage on the building either in external or internal structural frames, by collapse of walls etc. These kinds of affliction are uncommon and man-made disasters. The impact of blast load is equivalent to a dynamic loads and that demand to take caution while calculating of it. Someone can calculate as other lateral forces like earthquake and wind load. Design fully blast resistant structures is not pragmatic and economic, till the knowledge of mitigating its effect while designing new structures or maintaining old one with its less impact is identical. In this present study, the behavior of G+15 storey RCC structure is analyzed under the blast load with the help of ETAB software. According to the IS code provision, the dead load, live load and wind load has been considered to study the effect of it. Also, the distance of blast and its charge weight is very according to IS 4991-1968.

Assessment of Blast Resistant Structures

According to National Crime Record Bureau (NCRB) report, accidents due to Fire has been ranked fifth it’s up by three positions from the last year’s ranking and accidents due to fire killed more human lives and lead to property loss. Due to explosive accidents, it revealed that loads, for example, the effect of essential sections, and effect of optional parts, and pressure by reflective and blast waves are generated and it collapses the whole structure. To overcome the damages due to fire accidents, strengthening of members, protection to the structure, design the structural member as a more adequate to resist the blast load and design the structure as a blast resistant may be good. In this paper, various structural members due to blast load and the numerical methods to persist the blast load behaviour are reviewed. The behaviours of various type of concrete under blast load were discussed. Based on the review, it may be concluded that to avoid explosive collapse the structural member has to be designed to withstand the blast waves and utilization of adaptable type materials which was light in weight result by decreasing transfer of energy and less strength, less ductile fibres mixed into the concrete will give blast performance to the concrete.

Analysis of Blast Resistant Structure (TNT Storage Case Study)

The explosions produce extreme and unique loading on structures and can cause widespread damage to the building’s structural elements. Design of blast resistant structures provides structural integrity and acceptable levels of safety for buildings. The previous studies show that some structural systems could provide substantial increase in protection against blasts. This paper discussed the behavior of TNT loaded storage (a framed reinforced concrete (. the results of calculated pressure Using Reference (UFC)-3-340-02 [1] Equation and investigated that the average peak reflected pressure close to 5000 Psi. CSI-ETABS Software 3D model shows that the structural system of case study unsafe under 0.5 tons of TNT internal weight charge.

An overview of analysis of Cold-formed steel stud wall subjected to blast loading

This paper is aimed at presenting an overview of research performed worldwide related to analysis of Cold-formed steel (CFS) wall subjected to blast loading. The basics regarding definition of blast, the merits and demerits of using CFS for blast resistant structures, connection details, the methods of improving blast resistance of structures are included in this paper. The overview presented in this paper based on the earlier research works published in journal provide an insight into the topic and the research needs are also highlighted.

Determination of Effective Breadth Width of Steel Plate‐Stiffener Based on Nonlinear FE Analysis

ABSTRACTSteel plate‐stiffener systems are widely used in civil engineering applications especially for offshore and onshore oil and gas production facilities as blast walls and blast resistant steel modular structures, and in naval and aerospace engineering applications. Such structures are typically designed based on effective breadth width concept, which enables designer to estimate behaviour of the structure by use of simple beam theory. Although, most of design guidelines for breadth width are based on several idealized steel plate behaviour, the actual behaviour of steel plate is much more complex due to nonlinear 3D stress distribution and stress transfer between the stiffeners and plate. In this study, three prototype blast wall structures were designed with varying plate thickness and stiffener properties. The walls nonlinear behaviour including force‐deflection and longitudinal stress distribution through plate thickness and along plate width were investigated under out‐of‐plane static loading. The longitudinal stress distribution at different stress levels (i.e., elastic and several plastic levels) was used to determine effective breadth width. In addition, computed force‐deflection curves of walls and corresponding simple beams with different breadth widths were compared to verify computed breadth widths. The outcomes of this study indicate that computation of effective breadth width is much more complex and highly depends on stress levels and relative stiffness of plate and stiffeners.

The Development of a New Shock Absorbing Uniaxial Graded Auxetic Damper (UGAD).

Auxetic structures are efficient cellular materials that can absorb blast/impact energy through plastic deformation, thus protecting the structure. They are developing sacrificial solutions with light weight, high specific strength, high specific toughness and excellent energy dissipating properties, due to its negative Poison’s ratio nature. The use of auxetic and non-auxetic panels in blast resistant structures had been relatively perceived by researchers. Nonetheless, implementation of those energy dissipaters, explicitly as a uni-axial passive damper is restrained to limited studies, which highlight the potential need for further explorations. The aim of this paper is the design of a new uniaxial graded auxetic damper (UGAD) that can be used as a blast/impact/shock absorber in different scales for different structural applications. First, the geometry, material, numerical model and loading are introduced. Then, a detailed parametric study is conducted to achieve the most efficient graded auxetic system. Moreover, the designed auxetic damper is numerically tested and its static and dynamic constitutive relations are derived and validated analytically. The selection of optimum parameters was based on the ratio of the reaction force to the applied load (RFd/P) and plastic dissipation energy (PDE). The final designed UGAD contains three auxetic cores that have the same geometry, material grade (6063-T4), size and number of layers equal to eight. The cell-wall thickness t of the three auxetic cores is 1.4 mm, 1.8 mm and 2.2 mm, respectively; composing a graded auxetic system. The performance of the three auxetic cores together have led to a wide plateau region (80% of total crushing strain) and variant strength range (1–10 MPa), which in return, can justify the superior performance of the UGAD under different blast levels. Finally, the 3D printed prototype of the UGAD is presented and the possible applications are covered.

Quasi-static compressive behaviour of aluminium cenosphere syntactic foams

ABSTRACTIn this paper, cenosphere particles embedded in AA2014 aluminium matrix are used to fabricate syntactic foam by stir casting method. The particle size is about 100 µm and foam density is about 1990 kg m−3. Compression tests at strain rate 0.001/s are performed on foam samples to characterise their mechanical properties which are then used in numerical analysis on commercial finite element analysis software ABAQUS/CAE with isotropic elastic-plastic material model. Experimental and numerical results show good conformity in deformation behaviour with elastic and plateau zones showing average deviations less than 5% and 20%, respectively. Foams showed high yield stress and energy absorption capabilities that can be useful in making blast and impact resistant structures.

Multi-objective optimisation of steel moment frames subjected to blast

In recent decades, terrorist attacks have been increased all over the world. For this reason, the design of blast resistant structures is very crucial. On the other hand, for decades the optimum design of structures has been an interesting subject for structural engineers and researchers as it can provide cost and behavioural efficiencies. In the current research, the optimum design of steel moment frames under blast loading has been studied. Towards that end, first, a damage index is developed based on the maximum plastic strain in the members. Then, according to the damage index, a multi-objective optimisation methodology is proposed to minimise the structural weight and the damage index. The method utilises explicit nonlinear dynamic finite element analysis as the structural analysis method and NSGA-II optimisation algorithm as the optimisation technique. At the final point, based on the proposed method a framework is developed, and two numerical examples are studied. Results of this research show that the developed method is effective in achieving optimal designs with desired cost and damage.

Positive-Phase Blast Effects on Base-Isolated Structures

The last few decades have shown a dramatic increase in the number of man-made disaster activities resulting in extensive life loss and structural failures. The explosive devices used in these heinous acts result in blast wave loading. Therefore, the present structural engineers require comprehensive expertise to analyze and design blast-resistant structures. The present study aims to develop blast load time history based on the previous research works and demonstrates the effectiveness of base isolation technique such as lead rubber bearings in mitigating the structural responses under the effect of blast loading. Two base-isolated building models systems are analyzed to examine the role of structural control strategies subjected to blast loading. Various isolation parameters are also incorporated in the present investigation in improving the structural performance subjected to this extreme dynamic loading. The study concludes that base isolation is an efficient technique in reducing structural output parameters such as peak storey displacement, storey drift and root mean square absolute acceleration values due to post-blast effects. Energy-based equations are also examined in the study to evaluate the hysteretic energy dissipated by the system subjected to blast loading.

Dynamic behaviour of concrete containing aggregate resonant frequency

The need to design blast resistant civilian structures has arisen due to aggressor attacks on many civilian structures around the world. Achieving vibration and wave attenuation with locally resonant metamaterials has attracted a great deal of consideration due to their frequency dependent negative effective mass density. In this paper, metaconcrete, a new material with exceptional properties is formed. The aggregates in concrete are substituted with spherical inclusions consisting of a heavy metal core coated with a soft outer layer. The physics of the metamaterial was first established, and mass in mass-spring and effective mass system were shown to be equivalent. Then the engineered aggregate was tuned so that band gap was activated due to resonant oscillations of the replaced aggregate. In the numerical experiment conducted, the resonant behaviour causes the wave to be forbidden in the targeted frequencies. The proposed metaconcrete could be very useful in various civil engineering applications where vibration suspension and wave attenuation ability are in high demand.

Modeling, Simulation and Optimization of Steel Sandwich Panels under Blast Loading

Honeycomb sandwich panels are commonly preferred in structural engineering as a design element meant to protect against blast loading, and this owes primarily to the fact that they are light in weight (due to the voids present) whilst carrying high energy absorption capacities. A widespread surge in acts of terrorism, and the resultant threat posed to structures, presents structural engineers with unique challenges pertaining to the design of blast-resistant structures that are both safe and reliable. Researchers worldwide have thus taken to closely studying the effects of sudden loads effected by detonative forces on certain elements and design concepts. To this end, an emergent design concept with proven efficacy is the honeycomb sandwich panel. Due to the practical difficulties associated with the study of explosive materials and replicating blast loads, software-based modeling and simulation may be favorable as a functional and convenient alternative. To this end, this work uses the finite element package ABAQUS® to study the behavior of hexagonal and squared honeycomb steel sandwich panels under the explosive effects of different amounts of trinitrotoluene (TNT). The results of finite element modeling of a specific honeycomb configuration are initially validated by comparing them with the experimental results from literature. Several configurations including different geometrical properties of the honeycomb wall are then investigated and the results are compared. Consequently, an optimization study is conducted with an objective to reduce the plastic strain of the back plate while the wall cell thickness is taken as a variable. Finally, the effectiveness of the core shape and wall thickness is discussed and conclusions are made.

Recommendations for a New Generation of Standards for Testing Numerical Assessment of Blast-Loaded Glass Windows

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 regulations. This is especially true in the case of glass windows and facades, where the intrinsic material brittleness is the major influencing parameter for blast-resistant assemblies. While blast assessment of buildings and systems is usually achieved by means of experimental investigations, as well as Finite-Element numerical simulations, general regulations and guidelines are currently missing. In this regard, the European Reference Network for Critical Infrastructure Protection - Task Group (ERNCIP-TG) “Resistance of Structures to Explosion Effects” attempts to develop guidelines and recommendations aimed to harmonise test procedures in experimental testing of glass windows under blast, as well as standardized approaches for their vulnerability assessment via Finite Element numerical modelling. In this paper, major ERNCIP-TG outcomes and next challenges are briefly summarized.

06.07: Comparison of Blast Performance of Steel Modular Buildings with Anchored and Sliding Foundations

ABSTRACTA two‐module blast‐resistant steel building with overall dimensions of 12 m by 6 m floor plan and 3.4 m height was designed to resisted 80 kPa free field overpressure with 140 microsecond duration. The building was designed to remain within “high damage/response” level when it is anchored to its foundation. The effect of anchored and unanchored or sliding (free‐to‐slide) foundation on blast performance of structural elements on the wall and roof, foundation loads, building sliding, and building total friction and kinetic energy were investigated using nonlinear dynamic finite element analysis tools. The comparison of analyses results revealed that building foundation reactions and maximum deflection demands for structural members can significantly decrease with unanchored foundation. For unanchored foundation, several friction coefficients (i.e., 0.2, 0.5, and 0.8) for the interaction between the building and its foundation were considered. The analyses results show that the maximum relative deflections of the structural members of the building with unanchored foundation to be between 43% and 120% with an average of 80% of that for the building with anchored foundations. The most significant effect of unanchored foundation on blast performance of the building was the significant decrease in the foundation maximum horizontal reaction, which was approximately 15% to 60% of that for the building with anchored foundation. However, the unanchored foundation had negligible effect on building vertical foundation reactions. The computed maximum sliding displacements were approximately 10 m, 2 m and 0.3 m for the building with unanchored foundation for friction coefficient of 0.2, 0.5, and 0.8, respectively. For the building with unanchored and anchored foundations, both friction energy and kinetic energy versus time plots were very similar for initial stages of the blast loading. The overall results show that providing even limited permissible sliding between blast resistant structures and their foundation can significantly reduce their foundation reactions and improve blast performance of structural members. A controlled‐sliding mechanism between blast resistant structures and their foundation with steel cables is recommend to improve blast performance of the structure while limiting maximum sliding within desired permissible limits.

Основные методы оценки параметров ударных волн при аварийных взрывах. Принципы проектирования взрывоустойчивых зданий и сооружений

Основные методы оценки параметров ударных волн при аварийных взрывах. Принципы проектирования взрывоустойчивых зданий и сооружений

Mechanical response of V shaped plates under blast loading

An assessment of structural response of blast resistant structures is important for the efficient design of armored personal vehicles (APV). A rigid design of these structures will transfer the blast forces into the crew cabin whereas softer design will lead to excessive structure deformation which is dangerous to the crew. An optimal design should absorb the energy as much as possible and transmit less vibration to the crew in the cabin. For this purpose the effectiveness of different V-shaped plates are investigated here for finding its response under different plate angles, mass and eccentricity of the TNT charge. The assumed geometry is similar to that of plates used in the armored personal carrier CASSIPIR and the material under consideration is mild steel. Three-dimensional (3D) numerical analyses was performed using the non-linear finite element (FE) code ABAQUS/Explicit to predict the maximum central deflection, impulse transmitted and damage mode of V shaped plates. Results of the numerical simulation for failure in V shaped plates with different included angles(145,160,180 degrees), subjected to localized blasts are presented here. It is seen that primary variables like mass of the charge, the V-angle and eccentricity of the explosive affect the response variables of the plate.

Time Domain Spectral Element method to Study Response of a Sandwich Beam with Compliant Core Subjected to Under Water Explosion

A spectral element formulation is developed for a sandwich beam with stiff face sheets and a compliant core. Higher order displacement functions are taken for the core in order to incorporate the core compression effects. Highly efficient spectral element method is used for the study. Accuracy and the computational efficiency of this method are compared with the conventional finite element method in solving transient blast loading case. Using this spectral element method, under water blast loading response of a sandwich beam with composite face sheets and core is studied. A comparison is made between the response of stiff core and compliant core sandwich beam models. The study presents a design approach for an optimal configuration for under water blast resistant structures.

Static and dynamic analyses of insulated concrete sandwich panels using a unified non-linear finite element model

Insulated concrete sandwich panels are comprised of two outer concrete wythes and an inner layer of foam insulation. They have been increasingly used because of their advantages of light weight and energy efficiency. Various shear connectors can be used to connect the two outer concrete wythes. More recently, Fiber-Reinforced Polymer (FRP) shear connectors have been used, which can eliminate thermal bridging and improve the thermal performance. Typical approaches to Finite Element (FE) analysis treat static and dynamic analyses separately. However, due to the flexibility of the FRP shear connectors and the cracking of the concrete in insulated concrete sandwich panels, a nonlinear static analysis model would often diverge early based on a preliminary FE study conducted by the authors. To address this issue, a nonlinear explicit dynamic FE model using ABAQUS© was developed, which can study both the panels’ static behavior under typical flexural loading and dynamic behavior under blast loading. Nonlinear material properties were incorporated and damaged plasticity model was used to model concrete in both compression and tension. In order to simulate the static behavior, the time loading control was applied to the FE model to slow down the rate of loading to smoothly capture the response. For dynamic analysis under blast loading, a verification study was conducted first using the developed FE model, where good correlations can be obtained between the FE and test results on a panel tested in a previous study. The FE model was further used to study the dynamic behavior of two panels under blast loading: one is a solid concrete panel and the other is an insulated concrete sandwich panel. It can be concluded that, although the insulated concrete sandwich panel is lighter, it still performs relatively well compared to the solid panel under blast loading. Therefore, it is promising to use insulated concrete sandwich panels for both conventional and blast-resistant structures.

A modified layered-section method for responses of fire-damaged reinforced concrete beams under static and blast loads

Reinforced concrete structures are currently under the threat of both fire and blast. The absence of theoretical methods demonstrates a drawback in the assessment of blast-resistant structures after exposure to fire. A modified layered-section method was developed in this article, which was not only able to determine the complete static resistance–deflection curves of fire-damaged reinforced concrete beams but also able to predict the responses of reinforced concrete beams subjected to blast after fire exposure. The high-temperature effects and the strain-rate effects were included in the concrete and steel material models in the proposed method. A corresponding calculation program FBBA was also compiled based on the explicit Newmark algorithm on the platform of Maple software. The developed method and program were validated by the existing test results. Analytical results showed that after fire exposure, the reinforced concrete beams show significant degradation in the residual bearing capacity, but increase in the ductility. The higher the steel reinforcement ratio, the more degradation the bearing capacity of reinforced concrete beams after fire exposure suffers. The blast resistance of the fired reinforced concrete beams was underestimated without considering the strain-rate effects or just considering the average strain-rate effects.

Design and Analysis of HPFRCC Blast Resistant Structures

In the past few years, the increase in the number of terrorist attacks has shown that the effect of blast loads on buildings is a serious matter that should be taken into design consideration. These man-made disasters has created a challenge to structural engineers world over about the deficiency in the design process. Blast loads are extreme, instantaneous, unpredictive impulses acting over milliseconds. Due to this nature of blast loads, it is complicated to analyse the dynamic responses of the structures. Usage of advanced engineering materials for construction can solve these structural problems to an extent. This paper presents the design and analysis of an underground blast resistant shelter made up of high performance fiber reinforced cementitious composites (HPFRCC). This research focuses on an alternative section of cylindrical module of the shelter. The dynamic behavior of module under blast load is studied in finite element software Abaqus CAE 6.12. It is observed that the material stress-strain behavior is greatly influenced by strain rates of loadings. Shelter manually designed using codes in limit state method is verified with the analytical analysis.

Influence of barrier material and barrier shape on blast wave mitigation

This paper investigates means for increasing the effectiveness of a blast barrier using various types of surfacing. It builds on previous research on the blast effect mitigation properties of rigid concrete blast barriers. Previous research has studied barriers with a smooth surface. The effectiveness of rigid smooth barriers in reducing shock wave overpressure has been proven to be low. Their main contribution is in absorbing flying debris or shrapnel created by an explosion, and thereby reducing the risk of injury to the occupants of a building. This paper suggests ways to achieve greater safety by increasing the blast mitigation properties of barriers. It studies the influence of various materials and shapes on the effectiveness of a barrier, and proposes methods for providing increased overpressure reduction while keeping the same overall dimensions. A barrier of this kind provides additional security for the occupants of a building without disrupting the functionality of the interior with a massive obstacle. The use of a deformable porous material is compared with the use of rigid durable ultra-high performance fibre-reinforced self-compacting concrete (UHPFRSCC), developed by the authors especially for application in blast-resistant structures. The results of an original experimental program are used to determine the influence of barrier shape and barrier material on blast wave mitigation. The effect of uneven barrier surfacing on a shock wave is demonstrated on a finite element numerical model calculated using LS-DYNA. Results of the analysis proved that the use of uneven surface has a positive effect on blast mitigation properties of a barrier without affecting its shrapnel absorption capabilities. All experiments and FEM models consistently proved that a barrier has significant overpressure reduction effect in the area directly behind the barrier. The comparison of experimental measurements of rigid and deformable barrier material showed no drastic increase in mitigation properties of deformable barrier.