Identifying the hysteretic energy demand and distribution in regular steel frames

Jay Shen,Bulent Akbas,Hakan Temiz 국제구조공학회 2006 Steel and Composite Structures, An International J Vol.6 No.6

Structures in seismic regions are designed to dissipate seismic energy input through inelastic deformations. Structural or component failure occurs when the hysteretic energy demand for a structure or component subject to an earthquake ground motion (EQGM) exceeds its hysteretic energy dissipation capacity. This paper presents a study on identifying the hysteretic energy demand and distribution throughout the height of regular steel moment resisting frames (SMRFs) subject to severe EQGMs. For this purpose, non-linear dynamic time history (NDTH) analyses were carried out on regular low-, medium-, and high-rise steel SMRFs. An ensemble of ninety EQGMs recorded on different soil types was used in the study. The results show that the hysteretic energy demand decreases from the bottom stories to the upper stories and for high-rise structures, most of the hysteretic energy is dissipated by the bottom stories. The decrease is quite significant, especially, for medium- and high-rise structures.

Seismic Axial Loads in Steel Moment Resisting Frames

Jay Shen,Bulent Akbas,Onur Seker,Bilge Doran,Rou Wen,Eren Uckan 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.2

During the 1994 Northridge Earthquake, many buildings with modern steel moment resisting frames (SMRFs) suffered from connection failures. One year later, similar damage has occurred in the 1995 Kobe earthquake in Japan. The unexpected seismic response of SMRFs resulted in comprehensive analytical and theoretical investigations and major changes in steel building design have been implemented consequently. One of the requirements in the subsequent seismic design codes is the stability check of the columns. Column yielding in a seismic force resisting systems (SFRSs) is not the desired damage mode and might result in column rupture or global buckling and threaten life safety. This study focuses on exploring the seismic axial loads for columns in SMRFs under strong ground motions. For this purpose, the increase in axial loads in low-, medium-, and high-rise SMRFs are investigated at the maximum lateral load level and the corresponding lateral displacement. The results are presented in terms of PHRs, average system overstrength factors (Ωo) of all columns in the frames under the selected ground motions, the distribution of Ωo in the individual columns in the frame, and axial load levels in columns. The results indicate that axial load level remains below 0.4 in the columns for low- and medium-rise frames, whereas it may get as high as 0.95 in highrise frames.

Green Tea Polyphenols Improve Bone Microarchitecture in High-Fat-Diet–Induced Obese Female Rats Through Suppressing Bone Formation and Erosion

Chwan-Li Shen,Ming-Chien Chyu,Jay J. Cao,James K. Yeh 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.5

This study evaluates the effects of green tea polyphenols (GTPs) on bone microarchitecture in high-fat-diet (HFD)–induced obese female rats. Thirty-six 3-month-old female rats were fed either a control diet or a HFD for 4 months. Animals in the control group continued on the control diet for another 4 months. Animals in the HFD group were divided into two groups, with 0.5 g/100 mL GTP (the HFD+GTP group) or without GTP (the HFD group) in drinking water, in addition to the HFD for another 4 months. Compared to the control group, the HFD group increased bone formation and erosion rates at the tibia, decreased trabecular volume and thickness, but had no impact on bone mineral density (BMD), trabecular number (Tb.N), and separation. Compared to the control group, the HFD+GTP group demonstrates a greater Tb.N at the proximal tibia, and a greater trabecular thickness at the femur and the lumbar vertebrae, but a smaller trabecular separation (Tb.Sp) and mineralizing surface at the proximal tibia, and a reduced endocortical mineral apposition rate (MAR) at the tibia shaft. Relative to the HFD group, the HFD+GTP group demonstrates (1) a higher BMD at the femur, a greater trabecular volume, thickness, and number at the proximal tibia, a larger cortical area and thickness at the tibial shaft, and a greater trabecular volume and thickness at the femur and the lumbar vertebrae, (2) a smaller Tb.Sp, MAR, bone formation rate, and eroded surface at the tibia. We concluded that GTP supplementation in drinking water improves bone microarchitecture in the HFD-induced obese female rats, possibly through suppressing bone turnover, resulting in a larger net bone volume.

Life-Sustaining Procedures, Palliative Care, and Cost Trends in Dying COPD Patients in U.S. Hospitals: 2005~2014

김선정,Ji Won Yoo,Jay Shen,Eunjeong Ko,Pearl Kim,Yong-Jae Lee,Jae Hoon Lee,Xibei Liu,Johnson Ukken,Mutsumi Kioka 한국호스피스완화의료학회 2018 한국호스피스.완화의료학회지 Vol.21 No.1

Purpose: Little is known regarding the extent to which dying patients with chronic obstructive pulmonary disease (COPD) receive life-sustaining procedures and palliative care in U.S. hospitals. We examine hospital cost trends and the impact of palliative care utilization on the use of life-sustaining procedures in this population. Methods: Retrospective nationwide cohort analysis was performed using National Inpatient Sample (NIS) data from 2005 and 2014. We examined the receipt of both palliative care and intensive medical procedures, defined as systemic procedures, pulmonary procedures, or surgeries using the International Classification of Diseases, 9th revision (ICD-9-CM). Results: We used compound annual growth rates (CAGR) to determine temporal trends and multilevel multivariate regressions to identify factors associated with hospital cost. Among 77,394,755 hospitalizations, 79,314 patients were examined. The CAGR of hospital cost was 5.83% (P<0.001). The CAGRs of systemic procedures and palliative care were 5.98% and 19.89% respectively (each P<0.001). Systemic procedures, pulmonary procedures, and surgeries were associated with increased hospital cost by 59.04%, 72.00%, 55.26%, respectively (each P<0.001). Palliative care was associated with decreased hospital cost by 28.71% (P<0.001). Conclusion: The volume of systemic procedures is the biggest driver of cost increase although there is a cost-saving effect from greater palliative care utilization.

A methodology to estimate earthquake induced worst failure probability of inelastic systems

Akbas, Bulent,Nadar, Mustafa,Shen, Jay Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.29 No.2

Earthquake induced hysteretic energy demand for a structure can be used as a limiting value of a certain performance level in seismic design of structures. In cases where it is larger than the hysteretic energy dissipation capacity of the structure, failure will occur. To be able to select the limiting value of hysteretic energy for a particular earthquake hazard level, it is required to define the variation of hysteretic energy in terms of probabilistic terms. This study focuses on the probabilistic evaluation of earthquake induced worst failure probability and approximate confidence intervals for inelastic single-degree-of-freedom (SDOF) systems with a typical steel moment connection based on hysteretic energy. For this purpose, hysteretic energy demand is predicted for a set of SDOF systems subject to an ensemble of moderate and severe EQGMs, while the hysteretic energy dissipation capacity is evaluated through the previously published cyclic test data on full-scale steel beam-to-column connections. The failure probability corresponding to the worst possible case is determined based on the hysteretic energy demand and dissipation capacity. The results show that as the capacity to demand ratio increases, the failure probability decreases dramatically. If this ratio is too small, then the failure is inevitable.

Life-Sustaining Procedures, Palliative Care, and Cost Trends in Dying COPD Patients in U.S. Hospitals: 2005~2014

Kim, Sun Jung,Shen, Jay,Ko, Eunjeong,Kim, Pearl,Lee, Yong-Jae,Lee, Jae Hoon,Liu, Xibei,Ukken, Johnson,Kioka, Mutsumi,Yoo, Ji Won Korean Society for Hospice and Palliative Care 2018 한국호스피스.완화의료학회지 Vol.21 No.1

목적: 미국 병원에서 만성폐색성폐질환으로 사망하는 환자의 연명치료 및 완화의료에 대한 연구는 부족한 현실이다. 이 연구에서는 병원의 의료비 추세 및 완화의료 이용 및 연명치료 이용과의 관련성을 파악하고자 하였다. 방법: 이 연구는 2005~2014년 미국 입원환자 샘플(National Inpatient Sample, NIS)을 후향적 코호트 디자인으로 전환하였으며, ICD-9-CM (International Classification of Diseases, 9th revision) 코드를 활용하여 완화의료 및 집중치료(전신지지치료, 호흡기치료, 호흡기 수술)를 받은 환자를 구분하였다. 결과: 연평균성장률(Compound Annual Growth Rates, CAGR)을 활용하여 병원 의료비의 시계열변화를 확인하였으며, 다수준 다변량 회귀분석을 통해 병원의 의료비에 영향을 미치는 요소를 파악하였다. 전체 77,394,755 입원 건 중 79,314명의 환자가 최종 분석에 사용되었다. 병원 의료비는 연평균성장률이 5.83% (P<0.001)였으며, 전신지지치료와 완화의료의 연평균성장률은 각각 5.98%와 19.89% 였다(모두, P<0.001). 전신지지치료, 호흡기 치료, 호흡기 수술은 각각 59.04%, 72.00%, 55.26%의 병원 의료비 상승에 영향을(모두, P<0.001) 주었던 반면 완화의료는 28.71%의 병원 의료비 감소에 영향을 주었다(P<0.001). 결론: 미국에서 만성폐색성폐질환으로 사망하는 환자 중 전신지지 치료는 병원 의료비 상승의 주된 원인인 반면 완화의료 이용은 비용절감에 영향이 있는 것으로 파악되었다. Purpose: Little is known regarding the extent to which dying patients with chronic obstructive pulmonary disease (COPD) receive life-sustaining procedures and palliative care in U.S. hospitals. We examine hospital cost trends and the impact of palliative care utilization on the use of life-sustaining procedures in this population. Methods: Retrospective nationwide cohort analysis was performed using National Inpatient Sample (NIS) data from 2005 and 2014. We examined the receipt of both palliative care and intensive medical procedures, defined as systemic procedures, pulmonary procedures, or surgeries using the International Classification of Diseases, 9th revision (ICD-9-CM). Results: We used compound annual growth rates (CAGR) to determine temporal trends and multilevel multivariate regressions to identify factors associated with hospital cost. Among 77,394,755 hospitalizations, 79,314 patients were examined. The CAGR of hospital cost was 5.83% (P<0.001). The CAGRs of systemic procedures and palliative care were 5.98% and 19.89% respectively (each P<0.001). Systemic procedures, pulmonary procedures, and surgeries were associated with increased hospital cost by 59.04%, 72.00%, 55.26%, respectively (each P<0.001). Palliative care was associated with decreased hospital cost by 28.71% (P<0.001). Conclusion: The volume of systemic procedures is the biggest driver of cost increase although there is a cost-saving effect from greater palliative care utilization.

Seismic behavior of liquid storage tanks with 2D and 3D base isolation systems

Samet Kılıç,Bülent Akbaş,Jay Shen,Fabrizio Paolacci 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.83 No.5

In past major earthquakes (1994 Northridge, 1995 Kobe, Chi-Chi 1999, Kocaeli 1999), significant damages occurred in the liquid storage tanks. The basic failure patterns were observed to be the buckling of the tank wall and uplift of the anchorage system. The damages in the industrial facilities and nuclear power plants have caused the spread of toxic substances to the environment and significant fires. Seismic isolation can be used in liquid storage tanks to decouple the structure and decrease the structural demand in the superstructure in case of ground shaking. Previous studies on the use of seismic isolation systems on liquid storage tanks show that an isolation system reduces the impulsive response but might slightly increase the convective one. There is still a lack of understanding of the seismic response of seismically isolated liquid storage tanks considering the fluid-structure interaction. In this study, one broad tank, one medium tank, and one slender tank are selected and designed. Two- and three-dimensional elastomeric bearings are used as seismic isolation systems. The seismic performance of the tanks is then investigated through nonlinear dynamic time-history analyses. The effectiveness of each seismic isolation system on tanks’ performance was investigated. Isolator tension forces, modal analysis results, hydrodynamic stresses, strains, sloshing heights and base shear forces of the tanks are compared. The results show that the total base shear is lower in 3D-isolators compared to 2D-isolators. Even though the tank wall stresses, and strains are slightly higher in 3D-isolators, they are more efficient to prevent the tension problem.

A methodology to estimate earthquake induced worst failure probability of inelastic systems

Bulent Akbas,Mustafa Nadar,Jay Shen 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.29 No.2

Earthquake induced hysteretic energy demand for a structure can be used as a limiting value of a certain performance level in seismic design of structures. In cases where it is larger than the hysteretic energy dissipation capacity of the structure, failure will occur. To be able to select the limiting value of hysteretic energy for a particular earthquake hazard level, it is required to define the variation of hysteretic energy in terms of probabilistic terms. This study focuses on the probabilistic evaluation of earthquake induced worst failure probability and approximate confidence intervals for inelastic singledegree-of-freedom (SDOF) systems with a typical steel moment connection based on hysteretic energy. For this purpose, hysteretic energy demand is predicted for a set of SDOF systems subject to an ensemble of moderate and severe EQGMs, while the hysteretic energy dissipation capacity is evaluated through the previously published cyclic test data on full-scale steel beam-to-column connections. The failure probability corresponding to the worst possible case is determined based on the hysteretic energy demand and dissipation capacity. The results show that as the capacity to demand ratio increases, the failure probability decreases dramatically. If this ratio is too small, then the failure is inevitable.

Parametric study on energy demands for steel special concentrically braced frames

Selçuk Doğru,Bora Akşar,Bülent Akbaş,Jay Shen 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.24 No.2

Structures are designed in such a way that they behave in a nonlinear manner when subject to strong ground motions. Energy concepts have been widely used to evaluate the structural performance for the last few decades. Energy based design can be expressed as the balance of energy input and the energy dissipation capacity of the structure. New research is needed for multi degree of freedom systems (MDOFs)-real structures- within the framework of the energy based design methodology. In this paper, energy parameters are evaluated for low-, medium- and high-rise steel special concentrically braced frames (SCBFs) in terms of total energy input and hysteretic energy. Nonlinear dynamic time history analyses are carried out to assess the variation of energy terms along the height of the frames. A seismic energy demand spectrum is developed and hysteretic energy distributions within the frames are presented.

흰쥐의 간질 소발작에 대한 전침자극의 억제

김여진 ( Yun Jin Kim ),김재효 ( Jay Hyo Kim ),마빙 ( Cheng Ma ),심매홍 ( Mei Hong Shen ),이충인 ( Zhong Ren Li ),손인철 ( In Chul Sohn ) 대한경락경혈학회 2006 Korean Journal of Acupuncture Vol.23 No.2

Objectives: We investigated the effect of electroacupuncture on epileptic rat model and its underlying mechanisms on suppression of the epilepsy. Methods: It was used pentylenetetrazol (35∼40 mg/kg. i.p) induced epileptic rat model and square wave electrical stimulations (5 mA, 5, 40 or 80 Hz frequency) was applied to acupoints on "Dazhui" and "Taichong" for 30min. Results: Electroacupuncture suppressed spikes and slow waves of EEG due to the epileptic condition. Out of electroacupuncture, a high frequency of 80Hz had a better effect for suppress epileptic EEG wave. Conclusions: Electroacupuncture can markedly reduce the excitability of cerebral cortex and strengthen the inhibitory process, checking epilepsy wave. Some intrathalamic nuclei have a promoting or inhibiting effect on epileptic EEG wave. This experimental study we are proposed to Electro-acupuncture can suppression epileptic rat model and it`s scientific mechanisms.