In the seismic analysis and design of structures, the true velocity and absolute acceleration are usually approximated by their corresponding pseudo-values. This approach is simple and works well for structures with s...In the seismic analysis and design of structures, the true velocity and absolute acceleration are usually approximated by their corresponding pseudo-values. This approach is simple and works well for structures with small damping （say, less than 15%）. When the damping of a structure is enhanced for the purpose of response reduction, it may result in large analysis and design errors. Based on theory of random vibration and the established mechanism of seismic response spectra analysis, a method is developed （1） to predict the relative velocity spectra with any damping ratio level directly from the 5% standard pseudo-acceleration spectrum; and （2） to estimate the peak absolute acceleration. The accuracy of both is validated by using two selected ensembles of ground motion records.展开更多
We present an investigation on the propagation properties of the chirped Airy vortex（CAi V） beams through slabs of left-handed materials（LHMs） and right-handed materials（RHMs）. We discuss the influence of chirpe...We present an investigation on the propagation properties of the chirped Airy vortex（CAi V） beams through slabs of left-handed materials（LHMs） and right-handed materials（RHMs）. We discuss the influence of chirped parameter C on the propagation of the CAi V beams through LHM and RHM slabs. Our simulation results show that a maximum accelerated velocity appears during the propagation process. The intensity concentration of the CAi V beams increases with the absolute value of the chirped parameter. The peak intensity of the CAi V beams changes abruptly, and the chirped parameter plays an active role on the difference of the maximum and the minimum. In the energy flow, we find that the effects of the chirped parameter on the strength of the vortex are different at different propagation distances.展开更多
基金Supported by： the Federal Highway Administration Under Grant No. DTFH61-98-00094Acknowledgement The authors greatly acknowledge the support for this study by the Federal Highway Administration through a contract to MCEER （Contract Number： DTFH61-98- C-00094）.
文摘In the seismic analysis and design of structures, the true velocity and absolute acceleration are usually approximated by their corresponding pseudo-values. This approach is simple and works well for structures with small damping （say, less than 15%）. When the damping of a structure is enhanced for the purpose of response reduction, it may result in large analysis and design errors. Based on theory of random vibration and the established mechanism of seismic response spectra analysis, a method is developed （1） to predict the relative velocity spectra with any damping ratio level directly from the 5% standard pseudo-acceleration spectrum; and （2） to estimate the peak absolute acceleration. The accuracy of both is validated by using two selected ensembles of ground motion records.
基金supported by the National Natural Science Foundation of China(Nos.11374107 and 11374108)the CAS Key Laboratory of Geospace Environment,University of Science and Technology of China,the Extracurricular Scientific Program of School of Information and Optoelectronic Science and Engineering,South China Normal University,the National Training Program of Innovation and Entrepreneurship for Undergraduates(No.20161405)the Special Funds for the Cultivation of Guangdong College Students’Scientific and Technological Innovation(No.pdjh2017b0137)
文摘We present an investigation on the propagation properties of the chirped Airy vortex（CAi V） beams through slabs of left-handed materials（LHMs） and right-handed materials（RHMs）. We discuss the influence of chirped parameter C on the propagation of the CAi V beams through LHM and RHM slabs. Our simulation results show that a maximum accelerated velocity appears during the propagation process. The intensity concentration of the CAi V beams increases with the absolute value of the chirped parameter. The peak intensity of the CAi V beams changes abruptly, and the chirped parameter plays an active role on the difference of the maximum and the minimum. In the energy flow, we find that the effects of the chirped parameter on the strength of the vortex are different at different propagation distances.
