In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpres...In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpressure, but also the impulse (hence the duration). For structures with a regular geometry, the blast load may be fairly well estimated using appropriate empirical formulae; however, for more complex situations, a direct simulation using appropriate computational techniques is necessary. This paper presents a numerical simulation study on the prediction of the blast load in free air using a hydrocode, with focus on the sensitivity of the simulated blast load to the mesh grid size. The simulation results are compared with empirical predictions. It is found that the simulated blast load is sensitive to the mesh size, especially in the close-in range, and with a practically affordable mesh grid density, the blast load tends to be systematically underestimated. The study is extended to internal blast cases. An example concrete slab under internal explosion is analyzed using a coupled analysis scheme. The internal blast load from the simulation is examined and the response of the RC slab is commented.展开更多
In order to improve the load capacity, seismic performance and performance-cost ratio of the columns, the concrete at the base of reinforced concrete （RC） columns is substituted with engineered cementitious composit...In order to improve the load capacity, seismic performance and performance-cost ratio of the columns, the concrete at the base of reinforced concrete （RC） columns is substituted with engineered cementitious composites （ECC） to form ECC/RC composite columns. Based on the existing material properties, the mechanical behaviors of the ECC columns, ECC/RC composite columns and RC columns were numerically studied under combined vertical and horizontal loading with the software of ATENA. Then, the failure mechanism of ECC columns and ECC/RC composite columns were comprehensively studied and compared with that of the RC columns. Then, the effects of the height of the ECC, the axial compression ratio, and the transverse reinforcement ratio on the mechanical behaviors of the composite or the ECC column are studied. The calculation results show that the ultimate load capacity, ductility and crack resistance of the ECC or ECC/RC composite columns are superior to those of the RC columns. The ECC/RC composite column with a height of the ECC layer of 1.2h （ h is the height of the cross section） can achieve similar mechanical properties of a full ECC column. With high shear strength, ECC can undertake the shear force and significantly reduce the amount of stirrups, avoiding construction issues and promoting its engineering application.展开更多
文摘In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpressure, but also the impulse (hence the duration). For structures with a regular geometry, the blast load may be fairly well estimated using appropriate empirical formulae; however, for more complex situations, a direct simulation using appropriate computational techniques is necessary. This paper presents a numerical simulation study on the prediction of the blast load in free air using a hydrocode, with focus on the sensitivity of the simulated blast load to the mesh grid size. The simulation results are compared with empirical predictions. It is found that the simulated blast load is sensitive to the mesh size, especially in the close-in range, and with a practically affordable mesh grid density, the blast load tends to be systematically underestimated. The study is extended to internal blast cases. An example concrete slab under internal explosion is analyzed using a coupled analysis scheme. The internal blast load from the simulation is examined and the response of the RC slab is commented.
基金The National Natural Science Foundation of China(No.51278118)the Natural Science Foundation of Jiangsu Province(No.BK2012756)the Key Project of Ministry of Education of China(No.113029A)
文摘In order to improve the load capacity, seismic performance and performance-cost ratio of the columns, the concrete at the base of reinforced concrete （RC） columns is substituted with engineered cementitious composites （ECC） to form ECC/RC composite columns. Based on the existing material properties, the mechanical behaviors of the ECC columns, ECC/RC composite columns and RC columns were numerically studied under combined vertical and horizontal loading with the software of ATENA. Then, the failure mechanism of ECC columns and ECC/RC composite columns were comprehensively studied and compared with that of the RC columns. Then, the effects of the height of the ECC, the axial compression ratio, and the transverse reinforcement ratio on the mechanical behaviors of the composite or the ECC column are studied. The calculation results show that the ultimate load capacity, ductility and crack resistance of the ECC or ECC/RC composite columns are superior to those of the RC columns. The ECC/RC composite column with a height of the ECC layer of 1.2h （ h is the height of the cross section） can achieve similar mechanical properties of a full ECC column. With high shear strength, ECC can undertake the shear force and significantly reduce the amount of stirrups, avoiding construction issues and promoting its engineering application.
