The basis for the NEHRP site coefficients is summarized in the paper. The comparison of site classification between China and US code provisions has been carried out. The relationship between two site classifications ...The basis for the NEHRP site coefficients is summarized in the paper. The comparison of site classification between China and US code provisions has been carried out. The relationship between two site classifications has been found by the analysis of wave velocity of site soil. Thus amplitude-dependent site amplification factors for China site classification has been gained by transformation from US amplification factors. Two amplification factors are specified： Fa for short periods and Fv for longer periods. On the contrast, there is only one long period factor and not a short period factor in the current China code provision.展开更多
Newmark design spectra have been implemented in many building codes, especially in building codes for critical structures. Previous studies show that Newmark design spectra exhibit lower amplitudes at high frequencies...Newmark design spectra have been implemented in many building codes, especially in building codes for critical structures. Previous studies show that Newmark design spectra exhibit lower amplitudes at high frequencies and larger amplitudes at low frequencies in comparison with spectra developed by statistical methods. To resolve this problem, this study considers three suites of ground motions recorded at three types of sites. Using these ground motions, influences of the shear-wave velocity, earthquake magnitudes, source-to-site distances on the ratios of ground motion parameters are studied, and spectrum amplification factors are statistically calculated. Spectral bounds for combinations of three site categories and two cases of earthquake magnitudes are estimated. Site design spectrum coefficients for the three site categories considering earthquake magnitudes are established. The problems of Newmark design spectra could be resolved by using the site design spectrum coefficients to modify the spectral values of Newmark design spectra in the acceleration sensitive, velocity sensitive, and displacement sensitive regions.展开更多
The adsorption of methyl orange（MO） on chitosan（CS） beads in aqueous solutions was investigated by a batch equilibration technique. Special emphasis was focused on the effect of sorbent concentration（cs） on the ...The adsorption of methyl orange（MO） on chitosan（CS） beads in aqueous solutions was investigated by a batch equilibration technique. Special emphasis was focused on the effect of sorbent concentration（cs） on the adsorp- tion equilibration of MO on CS beads. An obvious Cs-effect was observed in the adsorption equilibration, i.e., the ad- sorption amount（F） was declined with Cs increase. The classical Langmuir model adequately described the adsorption isotherm for each given cs. However, it could not be used to predict the cs-effect observed. The applicability of the Langmuir-SCA isotherm, a surface component activity（SCA） model equation, to fit the cs-effect data was examined. In the SCA model, the activity coefficient of sorbent surface sites, fsH2O, was assumed to be a function of cs due to the deviation of a real adsorption system from an ideal one, arisen from sorbent particle-particle interactions in real systems. The results show that the Langmuir-SCA isotherm could accurately describe the c：effect observed under the studied conditions. Furthermore, the effects of temperature（t）, pH, and electrolyte（NaNO3） concentration（ CNaNO3 ） on fsH2O were examined. The results show that fsH2O clearly decreased with increasing t（20-35℃） and pH（5-8）, but no obvious change in fsH2O was observed as CNaNO3 varied in a range 0.001-0.010 mol/L. These results give a better understanding of the cs-effect.展开更多
基金Joint Seismological Science Foundation of China (A07046).
文摘The basis for the NEHRP site coefficients is summarized in the paper. The comparison of site classification between China and US code provisions has been carried out. The relationship between two site classifications has been found by the analysis of wave velocity of site soil. Thus amplitude-dependent site amplification factors for China site classification has been gained by transformation from US amplification factors. Two amplification factors are specified： Fa for short periods and Fv for longer periods. On the contrast, there is only one long period factor and not a short period factor in the current China code provision.
基金Natural Sciences and Engineering Research Council of Canada (NSERC)University Network of Excellence in Nuclear Engineering (UNENE)
文摘Newmark design spectra have been implemented in many building codes, especially in building codes for critical structures. Previous studies show that Newmark design spectra exhibit lower amplitudes at high frequencies and larger amplitudes at low frequencies in comparison with spectra developed by statistical methods. To resolve this problem, this study considers three suites of ground motions recorded at three types of sites. Using these ground motions, influences of the shear-wave velocity, earthquake magnitudes, source-to-site distances on the ratios of ground motion parameters are studied, and spectrum amplification factors are statistically calculated. Spectral bounds for combinations of three site categories and two cases of earthquake magnitudes are estimated. Site design spectrum coefficients for the three site categories considering earthquake magnitudes are established. The problems of Newmark design spectra could be resolved by using the site design spectrum coefficients to modify the spectral values of Newmark design spectra in the acceleration sensitive, velocity sensitive, and displacement sensitive regions.
基金Supported by the National Natural Science Foundation of China（Nos.21173135, 51372141） and the Specialized Research Fund for the Doctoral Program of Higher Education of China（No.20110131130008）,
文摘The adsorption of methyl orange（MO） on chitosan（CS） beads in aqueous solutions was investigated by a batch equilibration technique. Special emphasis was focused on the effect of sorbent concentration（cs） on the adsorp- tion equilibration of MO on CS beads. An obvious Cs-effect was observed in the adsorption equilibration, i.e., the ad- sorption amount（F） was declined with Cs increase. The classical Langmuir model adequately described the adsorption isotherm for each given cs. However, it could not be used to predict the cs-effect observed. The applicability of the Langmuir-SCA isotherm, a surface component activity（SCA） model equation, to fit the cs-effect data was examined. In the SCA model, the activity coefficient of sorbent surface sites, fsH2O, was assumed to be a function of cs due to the deviation of a real adsorption system from an ideal one, arisen from sorbent particle-particle interactions in real systems. The results show that the Langmuir-SCA isotherm could accurately describe the c：effect observed under the studied conditions. Furthermore, the effects of temperature（t）, pH, and electrolyte（NaNO3） concentration（ CNaNO3 ） on fsH2O were examined. The results show that fsH2O clearly decreased with increasing t（20-35℃） and pH（5-8）, but no obvious change in fsH2O was observed as CNaNO3 varied in a range 0.001-0.010 mol/L. These results give a better understanding of the cs-effect.
