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Long-span reticulated dome is often considered as a landmark building of a region, so it is very important to investigate the dynamic response and propose the damage assessment method of reticulated dome under blast loading. In this article, a fine finite element model of Kiewitt8 (K8) single-layer reticulated dome was established by using ANSYS/LS-DYNA. The effects of standoff distance, charge weight, rise–span ratio, span, and roof weight on the responses of K8 single-layer reticulated dome were numerically studied. The results showed that the blast-resistant performance of reticulated dome with smaller rise–span ratio and larger span under exterior blast load was more advantageous. Although the blast-resistant capacity of reticulated dome with large span and large roof weight was favorable, the plastic deformations of reticulated dome members were small and the utilization of material was low at failure state. According to the dynamic response characteristics of plentiful K8 single-layer reticulated domes at different damage levels, a damage model of K8 single-layer reticulated dome under exterior blast load was proposed in this article to indicate the damage level and determine the ultimate strength. Besides, a new damage criterion for K8 reticulated dome was also defined. This damage model was defined based on the physical phenomena at different damage levels, which made the strength failure criterion had definite physical meaning. Using the proposed damage criterion and a new search algorithm for pressure and impulse, the pressure–impulse diagrams for the typical K8 reticulated dome were derived from the numerical simulations to evaluate the damage level of reticulated dome under blast loading. Finally, a method to determine the safety standoff distance for reticulated dome under given TNT charge weight was also proposed. [ABSTRACT FROM AUTHOR]

Two type novel aluminum foam filled energy absorption connectors were proposed to be inserted between the blast resistant façade and building to absorb blast energy and reduce blast load transferred to the building. In this paper, the nonlinear finite element (FE) method was adopted to study the energy absorption performances of the two type connectors. The FE models of the connectors under quasi-static compression loading were first established and the accuracies of the FE models were verified by comparing the force–displacement curves obtained from tests and FE analyses. Then, the FE models were used to investigate the effects of filled aluminum foam, plate thickness and geometry as well as aluminum foam width on the energy absorption performances of the two type connectors. It was found that the two type connectors showed comparable energy absorption performances and the specific energy absorption could be significantly improved by filling the connector with aluminum foam. [ABSTRACT FROM AUTHOR]

A novel multilayer façade system, which consisted of a water steel tank integrated with a layer of energy absorbing aluminum foam panel and a stiffened steel panel, was developed to resist blast loading. The blast resistance and response behavior of the proposed façade system were investigated using nonlinear finite element method. The accuracy of the numerical model was verified by comparing the predicted results with the test results. The analyses showed that the energy absorbing aluminum foam layer was capable of reducing the blast load acting on the façade panel and building. The blast resistance of the multilayer façade system could be further enhanced by increasing the aluminum foam layer thickness. An analytical model considering Dynamic Increase Factor (DIF) and coupled deflection mode shapes was developed to predict the displacement response of the façade system subjected to blast loading. The accuracy of the analytical model was validated by comparing the predicted results with the numerical results. It was found that the analytical model with varying DIF could provide better prediction of the displacement response of the multilayer water façade system as compared to the method using a constant DIF. [ABSTRACT FROM AUTHOR]

The blast response behaviors of curved Steel-Concrete-Steel (SCS) sandwich shells were investigated using nonlinear finite element method. The accuracy of the numerical model was verified against the available field blast test results. The numerical results showed that shear connectors played a vital role in bonding the face plates and concrete core and therefore improving the blast resistant capacity of curved SCS sandwich shell. In addition, different failure modes for the curved SCS sandwich shell under close- and far-field blast loading were observed, i.e., separation of rear plate from concrete core and buckling of face plates for the shell under close- and far-field blast loading, respectively. The effects of rise height (or rise to span ratio) and rear to front plate thickness ratio on the blast responses of curved SCS sandwich shells were also studied. Numerical results showed that the damage of curved SCS sandwich shell could be reduced by increasing rise height and rear to front plate thickness ratio. Moreover, the energy absorption efficiency of concrete core also showed increase with increasing rear to front plate thickness ratio. [ABSTRACT FROM AUTHOR]

The water storage tank was proposed as a multi-functional facade system characterizing energy saving and blast resisting. The energy saving performance, not presented in this paper, has been evaluated by experimental and numerical methods. The aim of this study is to propose simplified methods to reasonably predict the response of water storage tank under blast loading. Based on the equivalent single-degree-of-freedom (SDOF) method, the shock spectrum and dimensionless pressure–impulse (P–I) diagram were established, which can be used to evaluate the damage levels of water storage tanks subject to blast loading. The equivalent SDOF method cannot capture the varying deflection shape of structure during motion, herein the Lagrange equation method that allows for multiple deflection shape functions was proposed to predict the structural response. It was shown that the Lagrange equation method was better than the SDOF method since it could provide conservative predictions in all response regimes. Furthermore, the varying dynamic increase factor (DIF) with strain rate was incorporated into the Lagrange equation method to capture the strain rate effects. [ABSTRACT FROM AUTHOR]

The blast performance of water tank with an innovative energy absorbing support was studied to reduce the support reaction force and mitigate the damage on the water tank. The aluminum foam was adopted as the energy absorbing material, since it has high energy absorbing potential during crush plateau and safety backup zone after the compaction strain. Finite element model considering fluid and structural interaction in which the water is modeled using the Eulerian formulation and the steel tank by Lagrangian formulation is proposed. The proposed numerical model of water tank was verified by comparing the predicted results with the test results obtained from dynamic pressure tests on steel tanks filled with water. The numerical results showed that the support reaction force depends on the density and yield strength of the aluminum foams and the reaction force could be reduced significantly if softer aluminum foam was chosen. The total displacement of the water tank was increased by up to 38% due to the increase in deformation of the energy absorbing foam. The aluminum foam was proposed to absorb the blast energy and reduce the damage on the water tank. However, more damage on the water tank was observed when a very low density aluminum foam support was used. This was attributed to the increased external work done by blast loading which was higher than the energy absorbed by the aluminum foam support. [ABSTRACT FROM AUTHOR]

The numerical method was adopted in this paper to study the performance of water tank under blast loading. The established numerical model was verified by comparing with the test results and then utilized to study the effects of water on the response of water tank under blast loading. The numerical results showed that water can significantly reduce the response of water tank under blast loading through reducing the external work. As for the boundary reaction force, although the maximum boundary reaction force was increased by filling in water, the increase in maximum boundary reaction force was less significant as compared to the decrease in response. Besides, the positive duration of boundary reaction force was reduced by filling in water. The simply supported and axially restrained boundary conditions were compared to study their effects on the response of water tank. It was found that the blast resistant performance of axially restrained water tank could be significantly improved as compared to the simply supported water tank. This can be attributed to the increased internal energy and reduced external work by adopting the axially restrained boundary condition. [ABSTRACT FROM AUTHOR]

Abstract: The elaborate finite element model of Kiewitt-8 single-layer reticulated dome with span of 40m subjected to eccentric blast loading was established and all the process from the detonation of the explosive charge to the demolition of reticulated dome structure was reproduced. The blast performance of reticulated dome was numerically studied and two approaches to improve the blast resistant capacity of reticulated dome were discussed. Response types of reticulated dome under eccentric blast loadings were defined. Partially reinforcement of reticulated dome is found to be an effective and economical way to improve its blast resistant capacity compared with fully reinforced reticulated dome. The pre-designed openings on the wall to release blast loading were studied, which provided some guidance on the blast resistant design of such structures. [Copyright &y& Elsevier]

Explicit finite element programme LS-DYNA was used to simulate a long-span steel reticulated shell under blast loading to investigate the structural dynamic responses in this paper. The elaborate finite element model of the Kiewitt-8 single-layer reticulated shell with span of 40 m subjected to central blast loading was established and all the process from the detonation of the explosive charge to the demolition, including the propagation of the blast wave and its interaction with structure was reproduced. The peak overpressure from the numerical analysis was compared with empirical formulas to verify the credibility and applicability of numerical simulation for blast loading. The dynamic responses of the structure under blast loading with different TNT equivalent weights of explosive and rise-span ratios were obtained. In addition, the response types of Kiewitt-8 single-layer reticulated shell subjected to central explosive blast loading were defined. [ABSTRACT FROM AUTHOR]

A circular–triangular nested tube (CTNT) was proposed for dissipating impact or blast energy. Experimental studies on CTNT energy absorbers under a lateral quasi-static crushing load were first conducted to reveal their deformation modes, force–displacement responses, and energy absorption performances. In addition, the influences of the circular-tube thickness and triangular-tube shape on the energy absorption performances of CTNTs were also discussed. A new energy absorption parameter, average curvature change (ACC), was proposed for evaluating the influence of geometry on the performance of an energy absorber that dissipates energy through changes in its curvature; further, the optimum geometric performance of the proposed CTNT energy absorbers was demonstrated based on a comparison with other nested energy absorbers reported in extant literature. The blast responses of the CTNT energy absorbers used as sacrificial claddings were numerically studied. The numerical results clearly presented the deformation modes, blast load mitigation, and energy absorption performances of the sacrificial claddings. The deformation mode of a CTNT energy absorber used as sacrificial cladding under blast loading was significantly different from that under quasi-static loading because the inertial effect and energy absorption capacity of the CTNT energy absorber increased as the weight of the trinitrotoluene (TNT) charge was increased. Moreover, the transmitted force was found to be reduced by 50.1%–74.3% on employing the CTNT energy absorber as sacrificial cladding, and the reduction magnitude decreased as the TNT charge weight was increased. • A novel circular-triangular nested tube energy absorber was proposed. • Experimental tests on the energy absorbers under quasi-static load were conducted. • Blast response of the energy absorber as sacrificial cladding was numerically studied. • Different deformation modes were observed for the energy absorber under quasi-static and blast load. • Transmitted force was reduced by 50.1%–74.3% by employing the energy absorber as sacrificial cladding. [ABSTRACT FROM AUTHOR]

• A novel energy absorption connector with PU foam and multiple pleated plates was proposed and two deformation patterns of the connector was observed. • The proposed connector dissipated energy through plastic deformation of multiple plated plates and PU foam compression. • PU foam filler could evidently improve the energy absorption performance in terms of higher EA, SEA and CFE as well as stabilizing the deformation mode. • The developed analytical model considering the transient strain rate effect of steel and PU foam could offer acceptable predictions on the force–displacement responses of the connectors. An innovative energy absorbing connecter with polyurethane (PU) foam and multiple pleated (MP) plates was designed to be placed between blast-resistant façade and structure to absorb blast-related energy along with reducing peak blast pressure transferred to the structure. Since the energy absorbing connector usually experiences impact loading transferred from blast-resistant façade, the deformation modes, force–displacement responses and energy absorbing characteristics of the contrived connectors subjected to impact loading were evaluated via employing drop-weight impact tests and FE simulations. The energy absorption, specific energy absorption as well as crushing force efficiency of the connectors were quantitatively evaluated. The experimental results revealed that filling PU foam could evidently enhance the energy absorbing performance of the connectors via increasing energy absorption, specific energy absorption as well as crushing force efficiency. Besides, increasing angle θ 0 (angle between MP plate and flat plate) and thickness of MP plate also leaded to higher specific energy absorption and absorbed energy. Finally, an energy-balance based analytical model incorporating transient strain rate effects of both steel and PU foam was proposed, which could be employed as a simple alternative to quickly yield the force–displacement relation of the connector. The accuracy of the developed analytical model was also validated with the experimental and finite element results. [ABSTRACT FROM AUTHOR]

• Foam concrete filled aluminum tube is proposed as the energy-absorbing core. • Energy absorption capacity of single filled tube first decreases then increases with increasing foam concrete density. • Tube mutual squeezing improves energy absorption capacity of low-density foam concrete filled cladding. • Protective performance of cladding under blast is experimentally and numerically studied. • High-density foam concrete filler greatly reduces blast energy input to the cladding. • Increasing tube thickness and reducing tube spacing significantly increase peak transferred load. In the present study, a new sacrificial cladding with the core of foam concrete filled aluminum tube is proposed for structural protection to resist the blast load. First of all, the energy absorption capacity of a single aluminum tube filled with different densities of foam concrete and the cladding with the core of different densities of foam concrete filled aluminum tubes is experimentally investigated by the quasi-static compressive test. Then the blast test was conducted on the proposed cladding to experimentally examine its protective performance. In addition, with the validated numerical model by the blast test data, the effect of the density of foam concrete filler, the thickness of the aluminum tube, and the tube spacing on the protective performance of the cladding is numerically investigated. The quasi-static compressive test results show that the density of the foam concrete filler and the mutual squeezing between the tubes have a significant influence on the energy absorption capacity of the proposed cladding. The observed residual deflection of the rear panel in the blast test demonstrates that the protective performance of the proposed cladding could be significantly improved with increasing density of foam concrete filler. The numerical results show that increasing the density of foam concrete filler and the thickness of aluminum tube, reducing the tube spacing are beneficial to reduce the energy input to the system. Meanwhile, the simultaneously increased stiffness of the cladding would lead to a significant increase in the peak load transferred to the protected structure. [ABSTRACT FROM AUTHOR]

To dissipate a large amount of blast energy as well as realize a reasonable load transfer to the beam and column instead of the vulnerable wall in the frame structure, this study employs a novel double-layered system to protect the infilled vulnerable masonry wall to resist blast loads. The system comprises a sacrificial cladding directly exposed to the blast to dissipate energy and connectors to facilitate load transfer and mitigation. Based on the quasi-static compressive test on the connector, the field blast test on the sacrificial cladding and frame structure with an infilled masonry wall, their respective numerical models are established and validated with ANSYS/LS-DYNA, which facilitates the model establishment of the frame structure protected by the double-layered system subjected to blast load. The numerical results indicate that the system effectively mitigates the damage to the masonry wall and reduces the load transferred to the frame compared to that without protection. However, large bending deformation of the sacrificial cladding may still result in collision damage to the vulnerable wall which makes it difficult to be applied in engineering practice. To improve the protective performance of the double-layered system and reduce the possibility of the occurrence of a collision between the sacrificial cladding and the wall, several measures, including connector layout optimization, rear plate strengthening with stiffeners, and appropriate connector height determination have been proposed. The numerical results demonstrate that installing connectors at four edges, adding 5 × 5 stiffeners on the rear surface of the sacrificial cladding, and appropriately designing the height of the connector can significantly enhance the double-layered system's protective performance, which has practical significance in protecting vulnerable masonry wall in frame structure from blast loads. • A double-layered system is employed to protect masonry wall subjected to blast. • The system with merits of energy dissipation and reasonable load transfer. • The system with connector at four edges is superior to that at opposite edges. • Adding stiffeners can improve the protective performance of double-layered system. • Height of the connector affects allowable and maximum deformation of cladding. [ABSTRACT FROM AUTHOR]

A novel cladding–connector system with excellent energy absorption capacity was proposed to protect vulnerable walls in frame structures subjected to blast load in the present study. The cladding–connector system was constructed by combining a sacrificial cladding consisting of an aluminum foam core sandwiched by two steel plates and four connectors made of corrugated steel tubes. On one hand, the cladding absorbed a considerable amount of blast energy. On the other hand, the connectors controlled the load transfer to the protected structure to certain specific pre-defined value. With this approach, both relatively high energy absorption and relatively low load transfer can be achieved simultaneously. Specifically, based on the quasi-static compression test on the connectors and the field blast test on the sacrificial cladding, the numerical model of the proposed system was established with ANSYS/LS-DYNA and validated with the test results. Then the deformation mode, energy dissipation, and load transfer of the cladding–connector systems with flexible or rigid connectors under various charge weights were numerically studied and compared. Results showed that the proposed cladding–connector​ systems could dissipate a considerable amount of energy under blast, in which the major part was dissipated by the cladding and the rest by the connectors. Particularly, compared to the cladding–connector system with rigid connectors, the cladding–connector system with flexible connectors exhibited superior performance in terms of energy absorption and load transfer, especially under intense blast. With the merits of excellent energy absorption, significant blast intensity reduction, and load shift from the vulnerable walls to the load-bearing components, the proposed cladding–connector system with flexible connectors was more promising to effectively protect the existing frame structures against blast. • A cladding–connector system is proposed to protect walls of frame structures subjected to blast. • The proposed system shifts the blast load applied on the wall to the load-bearing frame. • The system simultaneously realizes favorable energy absorption and load transfer control. • The system absorbs a considerable amount of energy in a designable manner. • The system reduces the transferred load intensity in a designable manner. [ABSTRACT FROM AUTHOR]