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Health monitoring of a bridge system using strong motion data
Mosalam, K.M.,Arici, Y. Techno-Press 2009 Smart Structures and Systems, An International Jou Vol.5 No.4
In this paper, the acceptability of system identification results for health monitoring of instrumented bridges is addressed. This is conducted by comparing the confidence intervals of identified modal parameters for a bridge in California, namely Truckee I80/Truckee river bridge, with the change of these parameters caused by several damage scenarios. A challenge to the accuracy of the identified modal parameters involves consequences regarding the damage detection and health monitoring, as some of the identified modal information is essentially not useable for acquiring a reliable damage diagnosis of the bridge system. Use of strong motion data has limitations that should not be ignored. The results and conclusions underline these limitations while presenting the opportunities offered by system identification using strong motion data for better understanding and monitoring the health of bridge systems.
Health monitoring of a bridge system using strong motion data
K. M. Mosalam,Y. Arici 국제구조공학회 2009 Smart Structures and Systems, An International Jou Vol.5 No.4
In this paper, the acceptability of system identification results for health monitoring of instrumented bridges is addressed. This is conducted by comparing the confidence intervals of identified modal parameters for a bridge in California, namely Truckee I80/Truckee river bridge, with the change of these parameters caused by several damage scenarios. A challenge to the accuracy of the identified modal parameters involves consequences regarding the damage detection and health monitoring, as some of the identified modal information is essentially not useable for acquiring a reliable damage diagnosis of the bridge system. Use of strong motion data has limitations that should not be ignored. The results and conclusions underline these limitations while presenting the opportunities offered by system identification using strong motion data for better understanding and monitoring the health of bridge systems.
Response Spectrum Code-Conforming PEER PBEE using Stochastic Dynamic Analysis and Information Theory
Umberto Alibrandi,Khalid M. Mosalam 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.3
In this paper, the tools of the stochastic dynamic analysis are adopted for Performance-Based Earthquake Engineering (PBEE). The seismic excitation is defined through a evolutionary Power Spectral Density compatible with the response spectrum given by mandatory codes. In this way, the performance-based design is applied considering the excitation coherent with the codes. Inside the framework, the seismic fragility curves are determined through the Kernel Density Maximum Entropy Method (KDMEM), recently proposed by the authors. It is a novel statistical method capable to reconstruct the seismic fragility curves, including the tails, from a small number of code-conforming artificial ground motions. Moreover, KDMEM is based on the Maximum Entropy (ME) principle and it provides the least biased probability distribution given the available information. Comparison between stationary and nonstationary artificial accelerograms is analyzed, and the corresponding model uncertainty discussed. KDMEM provides also credible bounds of the uncertain performances, which is beneficial for risk-informed decisions. The proposed formulation does not require the selection of a suitable set of ground motions. Accordingly, it can be adopted for optimal design in current engineering practice. Therefore, it fills the gap between the classical code-conforming designs and the enhanced performance-based designs.
Resistin and Insulin Resistance: A Link Between Inflammation and Hepatocarcinogenesis
Elsayed, Engy Yousry,Mosalam, Nesreen Ahmed,Mohamed, Noha Refaat Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.16
Background: Hepatocellular carcinoma (HCC) is the sixth most common cancer and the third leading cause of cancer related death overall. The role of insulin resistance in the development of HCC associated with chronic HCV infection has not been established. Resistin is a polypeptide hormone belonging to the adipokine family which could contribute to tumorigenesis and angiogenesis. Our aim was to study serum resistin and insulin resistance as risk factors for HCC in HCV cirrhotic patients. Materials and Methods: This prospective case controlled study included 100 patients with HCV related liver cirrhosis and HCC, 100 patients with HCV related liver cirrhosis without HCC and 50 apparently healthy participants as controls. For all subjects, liver profile, serologic markers for viral hepatitis, lipid profile, alpha-fetoprotein level (AFP), homeostasis model assessment (HOMA) were examined along with resistin. Results: HCC patients had higher mean values of HOMA-IR and resistin than cirrhotic patients and the control subjects (p<0.01). HOMA and resistin were considered independent risk factors in development of HCC, those patients with resistin > 12 ng/ml and HOMA > 4 being 1.6 times more likely to have HCC. Conclusions: HOMA and serum resistin allow for early identification of patients with cirrhosiswho are at substantially increased risk of HCC. Recommendation: HOMA and serum resistin could represent novel markers to identify HCV cirrhotic patients at greater risk of development of HCC.
Investigation of short column effect of RC buildings: failure and prevention
Ismail H. Cagatay,Caner Beklen,Khalid M. Mosalam 한국계산역학회 2010 Computers and Concrete, An International Journal Vol.7 No.6
If an infill wall in a reinforced concrete frame is shorter than the column height and there is no initial gap between the column and the infill wall, the short column effect can occur during an earthquake shaking. This form of damage is frequently observed in many earthquake-damaged buildings all around the world and especially in Turkey. In this study, an effective method, which consists of placing additional infill wall segments surrounding the short column, to prevent this type of failure is examined. The influence of adding infill wall in the reduction of the shear force in the short column is also investigated. A parametric study is carried out for one-storey infilled frames with one to five bays using the percentage of the additional infill wall surrounding the short column and the number of spans as the parameters. Then the investigation is extended to a case of a multistorey building damaged due to short column effect during the 1998 Adana-Ceyhan earthquake in Turkey. The results show that the addition of the infill walls around the potential short columns is an effective way to significantly reduce the shear force.
Zhenyu Yang,Chang He,Khalid M. Mosalam,Qiang Xie 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.82 No.6
The suspension thyristor valve can generate tremendous vertical acceleration responses in layers and large tension forces in hangers. A shaking table test of a scaled-down model of thyristor valves suspended on a hall building is performed to qualify the risk of vertical uplift of two representative types of valves, the chain valve and the rigid valve. Besides, an analytical model is established to investigate the source of the slackening of hangers. The test results show that the valves frequently experience a large vertical acceleration response. The soft spring joint can significantly reduce acceleration, but is still unable to prevent vertical uplift of the chain valve. The analytical model shows a stiffer roof and inter-story connection both contribute to a higher risk of vertical uplift for a rigid valve. In addition, the planar eccentricity and short hangers, which result in torsional motion of the valve, increase the possibility of vertical uplift for a chain valve. Therefore, spring joints with additional viscous dampers and symmetric layout in each layer are recommended for the rigid and chain valve, respectively, to prevent the uplift of valves.