Many materials are available for retrofitting masonry infill walls to resist explosion loads. Selection of the most suitable material is essential for optimal performance and cost. In this study, a series of trials were conducted in a specially designed test setup to determine and compare the performances of 1/2-scale masonry infill walls retrofitted with carbon fibre-reinforced polymer strips, steel wire mesh and laminated steel bars, respectively, as well as an unreinforced masonry wall, subjected to blast loads. High fidelity FE models with detail modelling of brick, mortar and retrofitting materials are also developed in LS-DYNA to simulate the blast tests. The accuracy of the FE models in predicting the field blast tests is verified with the test data. The calibrated FE models are used to perform intensive numerical simulations to investigate the effectiveness of various retrofitting measures. The displacement response, failure mode, level of damage and fragmentation from both the field blasting tests and numerical simulations are compared and used to assess the effectiveness of the retrofitting measures. The results demonstrate that the URM retrofitted with steel mesh performed the best among the three retrofitting measures in blast loading resistance, the wall retrofitted with closely spaced CFRP strips performed slightly better than that with steel bars.
This paper is composed of two parts: the generation of the sand particulate system and insights into the grain-level response under static and dynamic loadings. First, the algorithms for the generation of sand particles are presented, considering the randomness in their shape and distribution. Improvements to the robustness of the algorithms are obtained using controlling parameters. Second, we employ the take-and-place algorithm, placing sand grains into the specimen and checking how they overlap to form the initial model. In order to improve the porosity of the specimen, we develop the compaction algorithm: self-compaction by gravity and artificial compaction by mechanical vibration and pressure. The steps for the generation of a finite element grid are also introduced. Third, the grain-level configurations of the dry sand particulate system (aspects such as porosity, friction and contact) are taken into account in modelling. Results show that the grain-level responses of grains, i.e. deformation, fracture and damage of sand grains, impose significant effects on the mechanical behavior of dry sand under static and dynamic loadings.
This article is aimed to reveal the dynamic response of layered graded metallic foam under impact loading using a three-dimensional mesoscopic model. First, a mesoscopic model for closed-cell metallic foam is proposed based on the X-ray computed tomography images. Second, a numerical analysis approach is presented and validated with test data. Third, it studies the dynamic behavior of the layered graded metallic foam under impact loading numerically. The metallic foam specimen is composed layer by layer. The porosity, which is a fraction of the voids volume over the total volume, is different with each other for the layers. Simulations are conducted to the specimen with increasing and decreasing porosity arrangement. Results show that the layer arrangement is critical to the dynamic properties. The mesoscopic deformation of cell walls and the energy absorption capability are also affected significantly. This article gives insights into the mechanical properties and mesoscopic deformation of layered graded metallic foam.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.