Multimodal Response Spectrum Method Analysis of Integral Abutment Curved Box Girder Bridge
In order to simplify analysis of the dynamic characteristics and seismic response of the integral abutment curved box bridge(IACBB), automatic iteration of the multimode modal response spectrum(MMRS) is realized by APDL language of the structure analysis software ANSYS according to the IACBB's structural characteristics. The realization flow of iterative MMRS in Ansys were presented. and the availability and precision of the iterative MMRS were examined by the time-history analysis. The result shows that 1）the iterative MMRS is a efficient simplify method, and can be used as an estimating method of seismic analysis for the bridge. And the method provides a reference for future similar structures. 2）several conclusions of earthquake response are given. The research results are helpful for the knowledge of mechanics property of the type of the bridges.
STATIC SOIL-STRUCTURE INTERACTION EFFECTS IN SEISMIC-ISOLATED BRIDGES
In this paper, the effect of soil–structure interaction on the seismic performance of seismic-isolated bridges is studied. For this purpose, two typical seismically isolated bridges are selected. The selected bridges have distinct features to represent those bridges with: (1) Heavy superstructure and light substructure and (2) light superstructure and heavy substructure. Detailed structural models of both bridges excluding and including the soil–structure interaction effects are first constructed. Iterative multimode response spectrum analyses of the bridges are then conducted considering the nonlinear behavior of the isolation bearings. The analyses results have revealed that soil–structure interaction effects may be neglected in the seismic analysis of seismic-isolated bridges with heavy superstructure and light substructure constructed on stiff soil. However, the soil–structure interaction effects need to be considered for bridges with light superstructure and heavy substructures regardless of the stif...
Study on Electrical Explosion Mechanism and Ignition Characteristics of Copper and Aluminum Powder Under Ignition Solid Propellant
In order to study the characteristic of the electrical explosion of copper and aluminum powders, a multilayer generator was designed, an experimental system was set up, and the parameters of metal powder electrical explosion were measured and analyzed. The results show that the duration of the electrical explosion process increases significantly due to the addition of metal powder. The duration of aluminum powder electrical explosion jet flow is ~86.36 ms due to its self-sustained combustion, which releases a large amount of energy, and a small fraction of aluminum powder particles is not burned. The duration of copper powder electrical explosion jet flow is ~15.84 ms, and most of the copper powder particles are in the solid state. The current pause process is absent; instead, the first discharge process is connected to the second discharge process. The effect of copper powder on the first discharge process is greater than that of aluminum powder. Furthermore, the ignition ability of copper powder electrical explosion to solid propellant is stronger than that of aluminum powder in a closed bomb experiment. These results are indubitably meaningful for the application of metal powder electrical explosion and ignition of solid propellant in an electrothermal chemical gun.