Blast Panels Research Articles

Mitigation of blast effects through novel energy-dissipating connectors

Explosions generate overpressures that can cause irreparable damage to structures. For many buildings, especially critical infrastructure, continued operation after an explosive attack is essential. The use of energy-dissipating methods will enable the protection of a structure and occupants from a blast and permit the timely repair and re-occupation of the building after an event. The concept behind the system presented is the creation of panels that can be used as cladding for structures. The panels are connected to the main structure using energy-dissipating component assemblies around the panel edge. When subjected to a blast load the panels transfer the blast pressure through the assemblies, thereby reducing the forces transmitted to the underlying structure. After an event, the panels and energy-dissipating component assemblies can be replaced quickly and easily, allowing the building to be reoccupied in a short time after an attack. This study focuses on the characterization of energy-dissipating component assemblies using static and dynamic laboratory testing. A predictive theory, supported by a single degree of freedom model, is developed and a general evaluation method proposed. Further laboratory testing expands the characterization of behaviour of the assemblies through experiments, with a blast generator in tension tests and in simulated blast panel tests. The time histories developed from tension tests are then compared to examine the effect of loading rate. The investigations on blast panels also include a comparison with predictions to determine whether the latter can describe the global behaviour of the system. Lastly, the response of the energy-dissipating component assemblies is evaluated in full-scale field blast tests on cladding panels.

Blast Performance of Composite Sandwich Structures

A range of composite sandwich panels with different polymeric foam cores and face-sheets were subjected to full-scale air and underwater blast testing. The air blast panels had glass fiber reinforced polymer (GFRP) face-sheets with three different polymeric foam cores: styrene acrylonitrile (SAN), polyvinylchloride (PVC) and polymethacrylimide (PMI). The panels were subjected to 100kg TNT equivalent charge from a stand-off of 15 m. The SAN panel had the lowest deflection and suffered from the least damage. The underwater blast panels had either a single density or graded density SAN foam core and either glass fiber reinforced polymer or carbon fiber reinforced polymer (CFRP) face-sheets. The research revealed that there is a trade-off between reduced panel deflection and damage. All the blast research that has been performed is part of a program sponsored by the Office of Naval Research (ONR).

Non-linear Finite Element Analysis of Offshore Stainless Steel Blast Wall under High Impulsive Pressure Loads

Typical blast walls of offshore platform are stainless steel light-weight walls installed to contain the effect of an accidental explosion on the topside of an offshore installation. These walls are mostly designed using simplified analytical techniques like single degree of freedom (SDOF) method using global deformation or displacement as primary response parameter. Thin plate structures like stainless steel blast walls when subjected to high impulsive pressure loads, may damage severely in a particular region without experiencing a significant global deformation. This study presents realistic responses of offshore blast walls under various high impulsive pressure loads generated from accidental hydrocarbon explosions by using detailed non-linear finite element analysis (NFEA). The numerical models were verified against past experimental study on similar metal blast panels. An extensive parametric study was conducted using the verified finite element models to construct pressure-impulse (P-I) diagrams for different deformation levels. These P-I curves or iso-damage lines can be used as a quick assessment tool to determine possible level of damage of similar offshore blast walls due to different high impulsive pressure loading caused from different explosion scenarios.

Protective Structures Research at the University of Melbourne

Infrastructure engineering research at the University of Melbourne covers various subjects such as safe and sustainable structures, steel connections, high-strength concrete, earthquake engineering, dynamics of structures, and protective structures. The protective structures research group focuses on development of innovative and effective mitigation technologies for the protection of infrastructure from extreme human-caused acts and natural disasters. This paper presents the developments and future challenges in protective structures research, which falls within the scope of performance of structural components subjected to accidental or intentional blast effects, and the mitigation of these effects. The research group branches out into several key areas of interest such as performance and mitigation of structures against blast pressures, and glazing façade performance assessment under blast pressures. Developments of both analytical and experimental approaches in the key areas of interest will also be presented in this paper through a review of blast trials conducted in Woomera. Firstly, the loading characteristics were established in the blast trials and the analysis phase. Secondly, once the loading conditions were established the performance of local components (such as blast panels, concrete beams and façade components) was analysed. In this part, the performances of the modelling approach were assessed in comparison to the experimental results. The final part of this paper presents a study to establish the global behaviour of structures subjected to blast effects.

Protective structures research at the University of Melbourne

Infrastructure engineering research at the University of Melbourne covers various subjects such as safe and sustainable structures, steel connections, high-strength concrete, earthquake engineering, dynamics of structures, and protective structures. The protective structures research group focuses on development of innovative and effective mitigation technologies for the protection of infrastructure from extreme human-caused acts and natural disasters. This paper presents the developments and future challenges in protective structures research, which falls within the scope of performance of structural components subjected to accidental or intentional blast effects, and the mitigation of these effects. The research group branches out into several key areas of interest such as performance and mitigation of structures against blast pressures, and glazing facade performance assessment under blast pressures. Developments of both analytical and experimental approaches in the key areas of interest will also be presented in this paper through a review of blast trials conducted in Woomera. Firstly, the loading characteristics were established in the blast trials and the analysis phase. Secondly, once the loading conditions were established the performance of local components (such as blast panels, concrete beams and facade components) was analysed. In this part, the performances of the modelling approach were assessed in comparison to the experimental results. The final part of this paper presents a study to establish the global behaviour of structures subjected to blast effects.

Some aspects of wedge impact on granular layers and attendant flows

We observed and measured impacts of steel wedges on layers of 200 μ m solid glass spheres and the subsequent response with the ultimate aim to establish the effectiveness of these materials for blast panels and energy absorption. The success of the layers to absorb and dissipate energy is quantified, especially as regards the unconfined free surface of the granular material and its ability to dissipate and redirect momentum laterally through wave-like motion. Experiments were conducted with two granular layer depths; two drop elevations; and three wedge angles. As expected, as the wedge included-angle increases the peak force increases significantly, whereas the period associated with the response is much-reduced. It was shown that with a reduction in layer thickness, the bed can be forced to vacate locally, and subsequently the wedge strikes the reservoir bottom causing a rapid rise to a very large peak force. It was seen that the included-angle 180° wedge caused predominantly solid-like response (i.e. compaction); the 102° wedge generated mostly viscous/fluid-like behavior (i.e. similar to a Newtonian fluid); and as might be expected the 141° wedge exhibited both fluid-like and solid-like behavior. High-speed imaging of the surface response for the viscous-like motion showed breaking wavelike characteristics. In addition granular material was forced upward in a thin free sheet with hexagonal structure. Lastly we quantified the peak force ratio, the impulse, and the energy dissipation in the underlying load cells for the 102° wedge impacting the 16.36 cm bed versus the same test with no bed in place. For this last comparison the peak force ratio exceeded 15; the impulse was about a third less for the granular bed; and the ratio of energy dissipation in the load cells was more than 200.

Performance of Hybrid-Fiber ECC Blast/Shelter Panels Subjected to Drop Weight Impact

This paper presents the results of an experimental study to evaluate the damage and failure mode of hybrid-fiber engineered cementitious composite (ECC) panels caused by large projectiles or fragments. The aim is to quantify the extent to which hybrid-fiber ECC improves the resistance of blast panels against impact loading. Drop weight tests were conducted on full-scale hybrid-fiber ECC blast/shelter panels (2 m×1 m×0.05–0.1 m) to study their response and performance under impact loading. Conventional steel reinforced concrete (RC) and steel fiber-reinforced concrete (FRC) blast panels were also tested to identify the advantages of using ECC in this application. Both the drop weight projectile with a hemispherical head and the panel specimen were instrumented to facilitate evaluation of the global and local response. The impact resistance of blast panels of different materials is evaluated in terms of the extent of damage, energy absorption capacity and residual resistance against multiple impacts. The dr...

Experimental investigation of blast wall panels under shock pressure loading

A series of field tests was carried out at the BakerRisk test site in San Antonio, Texas on 1 4 -scale stainless-steel blast panels. The panel design was based on a deep trough trapezoidal profile, with welded angle connections at the top and bottom and free sides. The loading applied to the test panel was a shocked pressure pulse representative of the positive phase of the air blast loading arising from a high-explosive charge. The aim of this work was (1) to show the effect of panel response on the reflected blast loading and (2) to investigate the influence of the connection detail on the overall performance of the panel/connection system under shocked pressure loading. The data were also used to develop appropriate analytical and numerical models for correlation with the test results. Large permanent plastic deformations were produced in the panel without rupture. The work has shown that the connection detail can significantly influence the response and blast resistance of the panel to extreme pressure loading. The results highlight the conservative nature of the design guidance for blast wall design, which limits the deflections to 1 40 th of the height of the blast wall. This in turn should lead to more economical design. The results also concluded that further test work was required to confirm that the panel response had any appreciable effect on the pressure loading.

Validated finite element analysis model of blast wall panels under shock pressure loading

A series of field tests was carried out at the BakerRisk test site in San Antonio, TX, on 1/4 scale stainless steel blast panels. The panel design was based on a deep trough trapezoidal profile with flexible welded angle connections. The loading applied to the test panel was a shocked pressure pulse representative of an air blast. The aim of this work was to investigate the influence of the connection detail on the overall performance of the panel/connection system under shocked pressure loading. The data were also used to develop appropriate analytical and finite element numerical models for correlation with the test results. Large permanent plastic deformations were produced in the panel without rupture. The work has shown that the connection detail can significantly influence the response and blast resistance of the panel to extreme pressure loading. This, in turn, should lead to more economical design.