Real earthquake accelerograms are used in structural dynamic analysis.The criteria for record database establishment,record screening,selection principle,scaling adjustment,and sampling size are discussed in the prese...Real earthquake accelerograms are used in structural dynamic analysis.The criteria for record database establishment,record screening,selection principle,scaling adjustment,and sampling size are discussed in the present paper.An optimized selection method using coupled genetic and greedy algorithms is proposed,and energy input characteristics for the records which are selected only through matching acceleration design spectrum are analyzed.Using the proposed method,the mean and target spectra can reach a good agreement within a period range of interest.The dispersion among the response spectra of the different records is small,and the tolerance of the spectrum value corresponding to each period in the important period scope can be controlled more strictly than the specified limit.If the structural cumulative damage or structures with energy-dissipation components are considered,the records selected using the method that only match the acceleration design spectrum are not applicable.In this case,the selection method that considers the energy input demand is recommended.展开更多
Objective： To illustrate mechanisms of spine fractures and the pattern of spinal injuries characterized by the major mechanisms in urban population of Iran. Methods： Data regarding spinal injuries including demogra...Objective： To illustrate mechanisms of spine fractures and the pattern of spinal injuries characterized by the major mechanisms in urban population of Iran. Methods： Data regarding spinal injuries including demographics, mechanism and level of spinal injury, abbreviated injury score, associated injuries and final fate of the patients were extracted from the Iranian national trauma registry database from 1999 to 2004. Results： A total of 619 patients with traumatic spine fractures were identified, of whom 68.5% were males. The peak frequency of these injuries occurred in the 21-40 year age-group. Accidental falls and road traffic crashes （RTCs） were the most common mechanisms of spinal fractures （47.2% and 44.1%, respectively）. RTCs tended to occur in younger patients compared with accidental falls. The most common spinal region for spinal fracture was the lumbar spine （53.63%）. Cervical spine fractures were significantly more common in RTCs, while lumbar spine fractures were more common in accidental falls （P〈0.001）. A total of 171 （27.6%）patients had associated non-spinal injuries, of whom 127 had associated extremity injuries, and 55 had head injuries. Thirty-six （5.6%） patients had spinal cord injury （SCI）.The injury severity score of the RTC group was significantly higher than that of accidental falls （P=-0.002）. Fifteen （4%） patients died of traumatic injuries. The rate of death was significantly higher in RTCs compared with accidental falls （5.1% vs 2.1%, P=0.039）. Conclusions： The patterns of spinal fractures are similar to those reported from developed countries. RTCs tend to affect the younger age population and are associated with a higher degree of associated injuries and mortality than accidental falls. Therefore preventive strategies should be based on reduction of the number and severity of RTCs.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 90715016)
文摘Real earthquake accelerograms are used in structural dynamic analysis.The criteria for record database establishment,record screening,selection principle,scaling adjustment,and sampling size are discussed in the present paper.An optimized selection method using coupled genetic and greedy algorithms is proposed,and energy input characteristics for the records which are selected only through matching acceleration design spectrum are analyzed.Using the proposed method,the mean and target spectra can reach a good agreement within a period range of interest.The dispersion among the response spectra of the different records is small,and the tolerance of the spectrum value corresponding to each period in the important period scope can be controlled more strictly than the specified limit.If the structural cumulative damage or structures with energy-dissipation components are considered,the records selected using the method that only match the acceleration design spectrum are not applicable.In this case,the selection method that considers the energy input demand is recommended.
文摘Objective： To illustrate mechanisms of spine fractures and the pattern of spinal injuries characterized by the major mechanisms in urban population of Iran. Methods： Data regarding spinal injuries including demographics, mechanism and level of spinal injury, abbreviated injury score, associated injuries and final fate of the patients were extracted from the Iranian national trauma registry database from 1999 to 2004. Results： A total of 619 patients with traumatic spine fractures were identified, of whom 68.5% were males. The peak frequency of these injuries occurred in the 21-40 year age-group. Accidental falls and road traffic crashes （RTCs） were the most common mechanisms of spinal fractures （47.2% and 44.1%, respectively）. RTCs tended to occur in younger patients compared with accidental falls. The most common spinal region for spinal fracture was the lumbar spine （53.63%）. Cervical spine fractures were significantly more common in RTCs, while lumbar spine fractures were more common in accidental falls （P〈0.001）. A total of 171 （27.6%）patients had associated non-spinal injuries, of whom 127 had associated extremity injuries, and 55 had head injuries. Thirty-six （5.6%） patients had spinal cord injury （SCI）.The injury severity score of the RTC group was significantly higher than that of accidental falls （P=-0.002）. Fifteen （4%） patients died of traumatic injuries. The rate of death was significantly higher in RTCs compared with accidental falls （5.1% vs 2.1%, P=0.039）. Conclusions： The patterns of spinal fractures are similar to those reported from developed countries. RTCs tend to affect the younger age population and are associated with a higher degree of associated injuries and mortality than accidental falls. Therefore preventive strategies should be based on reduction of the number and severity of RTCs.
