The fifth-generation seismic hazard map for China's mainland(CSHM5) was developed based on the delineated seismic source models and the ground motion models(GMMs) for the peak ground acceleration(PGA) for four dif...The fifth-generation seismic hazard map for China's mainland(CSHM5) was developed based on the delineated seismic source models and the ground motion models(GMMs) for the peak ground acceleration(PGA) for four different seismic regions. In the present study, we developed a new set of GMMs as functions of the rupture distance or the closest distance to the projection of the rupture plane. The development of the GMMs is based on the projection method and GMMs from the NGA-West2 project. We then estimated, mapped, and compared the seismic hazard in terms of PGA and pseudo-spectral acceleration by using the new set of GMMs and other relevant GMMs, and two seismic source models-one used in developing CSHM5, which includes the fault orientation characterization and the other based on a spatially smoothed source model. The comparison of the estimated seismic hazard indicates that CSHM5 may significantly underestimate the seismic hazard. Part of this is likely due to the inclusion of an additional 15 km focal depth in the original GMM that is adopted for CSHM5. The comparison of the obtained standardized uniform hazard spectra(UHS) to the standardized response spectrum implemented in the current structural design code shows that the value of the latter is greater than that of the former for the natural vibration period less than about 0.1 s or greater than 0.4 s and this is reversed for the natural vibration period around 0.2 s. It is recommended that the use of UHS for design code making should be seriously considered, or at least, the shape of the current implemented standardized design spectrum could be improved.展开更多
Extreme snow loads can collapse roofs.This load is calculated based on the ground snow load(that is,the snow water equivalent on the ground).However,snow water equivalent(SWE) measurements are unavailable for most sit...Extreme snow loads can collapse roofs.This load is calculated based on the ground snow load(that is,the snow water equivalent on the ground).However,snow water equivalent(SWE) measurements are unavailable for most sites,while the ground snow depth is frequently measured and recorded.A new simple practical algorithm was proposed in this study to evaluate the SWE by utilizing ground snow depth,precipitation data,wind speed,and air temperature.For the evaluation,the precipitation was clas sified as snowfall or rainfall according to the air temperature,the snowfall or rainfall was then corrected for measurement error that is mainly caused by wind-induced undercatch,and the effect of snow water loss was considered.The developed algorithm was applied and validated using data from57 meteorological stations located in the northeastern region of China.The annual maximum SWE obtained based on the proposed algorithm was compared with that obtained from the actual SWE measurements.The return period values of the annual maximum ground snow load were estimated and compared to those obtained according to the procedure suggested by the Chinese structural design code.The comparison indicated that the use of the proposed algorithm leads to a good estimated SWE or ground snow load.Its use allowed the estimation of the ground snow load for sites without SWE measurement and facilitated snow hazard mapping.展开更多
The ice accretion load in Canadian structural design codes is developed based on an operational ice accretion prediction model.In the present study,three models are employed to predict the ice accretion amount on a fl...The ice accretion load in Canadian structural design codes is developed based on an operational ice accretion prediction model.In the present study,three models are employed to predict the ice accretion amount on a flat surface and horizontal wire at Canadian sites.The results confirm that the model used by Canadian practice for predicting ice accretion leads to a conservative estimate as compared to the remaining two models.The results also indicate that the use of the Gumbel distribution for the annual maximum ice accretion is adequate for regions prone to ice accretion and that the lognormal distribution may be considered for regions with a moderate or negligible amount of ice accretion.Maps of the ice accretion hazard at five selected Canadian sites are developed.Statistical analysis of an equivalent wind speed that is concurrent with the iced wire is carried out,showing that the concurrent wind speed for the 50-year return period value of the annual maximum ice accretion amount is smaller than the 50-year return period value of the annual maximum wind speed.It is shown that the statistical characteristics of the annual maximum concurrent wind speed on iced wire differ from that of the annual maximum wind speed.展开更多
基金supported by the Fundamental Research Funds for the Central Universities,CHD(Grant No.300102282103)Natural Science Basic Research Program of Shaanxi(Program No.2023-JC-QN-0512)(CF)+1 种基金the National Key R&D Program of China(Grant No.2023YFC3805202)(HPH)the Institute of Geophysics,China Earthquake Administration(WJX)is gratefully acknowledged.
文摘The fifth-generation seismic hazard map for China's mainland(CSHM5) was developed based on the delineated seismic source models and the ground motion models(GMMs) for the peak ground acceleration(PGA) for four different seismic regions. In the present study, we developed a new set of GMMs as functions of the rupture distance or the closest distance to the projection of the rupture plane. The development of the GMMs is based on the projection method and GMMs from the NGA-West2 project. We then estimated, mapped, and compared the seismic hazard in terms of PGA and pseudo-spectral acceleration by using the new set of GMMs and other relevant GMMs, and two seismic source models-one used in developing CSHM5, which includes the fault orientation characterization and the other based on a spatially smoothed source model. The comparison of the estimated seismic hazard indicates that CSHM5 may significantly underestimate the seismic hazard. Part of this is likely due to the inclusion of an additional 15 km focal depth in the original GMM that is adopted for CSHM5. The comparison of the obtained standardized uniform hazard spectra(UHS) to the standardized response spectrum implemented in the current structural design code shows that the value of the latter is greater than that of the former for the natural vibration period less than about 0.1 s or greater than 0.4 s and this is reversed for the natural vibration period around 0.2 s. It is recommended that the use of UHS for design code making should be seriously considered, or at least, the shape of the current implemented standardized design spectrum could be improved.
基金Financial support from the National Natural Science Foundation of China(Grant Nos.51808169 and 51927813)the Fundamental Research Funds for the Central Universities(Grant No.HIT.NSRIF.2020083)are gratefully acknowledged.
文摘Extreme snow loads can collapse roofs.This load is calculated based on the ground snow load(that is,the snow water equivalent on the ground).However,snow water equivalent(SWE) measurements are unavailable for most sites,while the ground snow depth is frequently measured and recorded.A new simple practical algorithm was proposed in this study to evaluate the SWE by utilizing ground snow depth,precipitation data,wind speed,and air temperature.For the evaluation,the precipitation was clas sified as snowfall or rainfall according to the air temperature,the snowfall or rainfall was then corrected for measurement error that is mainly caused by wind-induced undercatch,and the effect of snow water loss was considered.The developed algorithm was applied and validated using data from57 meteorological stations located in the northeastern region of China.The annual maximum SWE obtained based on the proposed algorithm was compared with that obtained from the actual SWE measurements.The return period values of the annual maximum ground snow load were estimated and compared to those obtained according to the procedure suggested by the Chinese structural design code.The comparison indicated that the use of the proposed algorithm leads to a good estimated SWE or ground snow load.Its use allowed the estimation of the ground snow load for sites without SWE measurement and facilitated snow hazard mapping.
基金financial support received from several agencies:the University of Western Ontario,the China Scholarship Council(No.201706260256,for Chao Sheng)the Natural Sciences and Engineering Research Council of Canada(RGPIN-2016-04814,for H.P.Hong),and the National Research Council(NRC)Canada.
文摘The ice accretion load in Canadian structural design codes is developed based on an operational ice accretion prediction model.In the present study,three models are employed to predict the ice accretion amount on a flat surface and horizontal wire at Canadian sites.The results confirm that the model used by Canadian practice for predicting ice accretion leads to a conservative estimate as compared to the remaining two models.The results also indicate that the use of the Gumbel distribution for the annual maximum ice accretion is adequate for regions prone to ice accretion and that the lognormal distribution may be considered for regions with a moderate or negligible amount of ice accretion.Maps of the ice accretion hazard at five selected Canadian sites are developed.Statistical analysis of an equivalent wind speed that is concurrent with the iced wire is carried out,showing that the concurrent wind speed for the 50-year return period value of the annual maximum ice accretion amount is smaller than the 50-year return period value of the annual maximum wind speed.It is shown that the statistical characteristics of the annual maximum concurrent wind speed on iced wire differ from that of the annual maximum wind speed.
