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Evaluation of required seismic gap between adjacent buildings in relation to the Egyptian Code
Manar M. Hussein,Ahmed A. Mostafa,Walid A. Attia 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.2
International seismic codes stipulate that adjacent buildings should be separated by a specified minimum distance, otherwise the pounding effect should be considered in the design. Recent researches proposed an alternative method (Double Difference Combination Rule) to estimate seismic gap between structures, as this method considers the cross relation of adjacent buildings behavior during earthquakes. Four different criteria were used to calculate the minimum separation distance using this method and results are compared to the international codes for five separation cases. These cases used four case study buildings classified by different heights, lateral load resisting systems and fundamental periods of vibrations to assess the consistency in results for the alternative methods. Non-linear analysis was performed to calculate the inelastic displacements of the four buildings, and the results were used to evaluate the relation between elastic and inelastic displacements due to the ductility of structural elements resisting seismic loads. A verification analysis was conducted to guarantee that the separation distance calculated is sufficient to avoid pounding. Results shows that the use of two out of the four studied methods yields separation distances smaller than that calculated by the code specified equations without under-estimating the minimum separation distance required to avoid pounding.
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Study of wind tunnel test results of high-rise buildings compared to different design codes
Abdulmonem A. Badri,Manar M. Hussein,Walid A. Attia 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.20 No.5
Several international codes have been developed for evaluating wind loads on structures; however, the wind structure interaction could not be accurately captured by these codes due to the gusty nature of wind and the dynamic behavior of structures. Therefore, the alternative wind tunnel testing was introduced. In this study, an introduction to the available approaches for wind load calculations for tall buildings was presented. Then, a comparative study between different codes: the Egyptian code, ECP 201-08, ASCE 7-05, BS 6399-2, and wind tunnel test results was conducted. An investigation has been carried out on two case studies tall buildings located within the Arabian Gulf region. Numerical models using (ETABS) software were produced to obtain the relation between codes analytical values and wind tunnel experimental test results for wind loads in the along and across wind directions. Results for the main structural responses including stories forces, shears, overturning moments, lateral displacements, and drifts were presented graphically in order to give clear comparison between the studied methods. The conclusions and recommendations for future works obtained from this research are finally presented to help improving Egyptian code provisions and show limitations for different cases.
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Study of wind tunnel test results of high-rise buildings compared to different design codes
Badri, Abdulmonem A.,Hussein, Manar M.,Attia, Walid A. Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.5
Several international codes have been developed for evaluating wind loads on structures; however, the wind structure interaction could not be accurately captured by these codes due to the gusty nature of wind and the dynamic behavior of structures. Therefore, the alternative wind tunnel testing was introduced. In this study, an introduction to the available approaches for wind load calculations for tall buildings was presented. Then, a comparative study between different codes: the Egyptian code, ECP 201-08, ASCE 7-05, BS 6399-2, and wind tunnel test results was conducted. An investigation has been carried out on two case studies tall buildings located within the Arabian Gulf region. Numerical models using (ETABS) software were produced to obtain the relation between codes analytical values and wind tunnel experimental test results for wind loads in the along and across wind directions. Results for the main structural responses including stories forces, shears, overturning moments, lateral displacements, and drifts were presented graphically in order to give clear comparison between the studied methods. The conclusions and recommendations for future works obtained from this research are finally presented to help improving Egyptian code provisions and show limitations for different cases.
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( Hoda El Aggan ),( Sabah Mahmoud ),( Nevine El Deeb ),( Amany Elyamany ),( Manar Attia ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1
Aims: Hepatitis C virus (HCV) is a major risk of hepatocellular carcinoma (HCC), however, the molecular mechanism of HCV-related hepatocarcinogenesis is still unclear. The polycistronic microRNA (miR)-17~92 cluster, designated also as “OncomiR-1”, plays a role in tumorigenesis and is transactivated by c-MYC oncogene. The cluster negatively regulates phosphatase and tensin homolog (PTEN) and activates nuclear factor-kappa B (NF-κB). The present study was designed to evaluate plasma levels of miR-17 host gene (MIR17HG) protein, encoded by miR-17~92 cluster host gene, in patients with HCV-related HCC in relation to tumor c-MYC, PTEN and NF-κB expression. Methods: Forty five patients with chronic HCV infection [18 patients with chronic hepatitis C (CHC), 12 patients with cirrhosis and 18 patients with HCC] and 15 healthy subjects were enrolled in the study. The HCC stage was determined according to the Barcelona Clinic Liver Cancer (BCLC) staging system and Cancer of the Liver Italian Program (CLIP). Quantitative measurement of plasma MIR17HG protein levels was performed using an enzyme-linked immunosorbant assay kit. The HCC histologic grade was assessed according to Edmonson and Steiner scoring system. Immunohistochemical staining of liver specimens was done using anti-human antibodies against c-MYC, PTEN and NF-kB and was scored semiquatitatively. Results: Plasma MIR17HG protein levels showed significant increases in CHC and cirrhotic patients with and without HCC compared with healthy subjects and in patients with HCC compared with those without HCC (P < 0.001). By plotting ROC curve, the sensitivity and specificity of plasma MIR17HG protein levels in detecting HCC were 100% and 93.3% respectively at a cut-off level of 257.25 pg/ml [AUC = 0.996]. The HCC tissues showed a significant increase in c-MYC, and NF-kB expression and a significant decrease in PTEN expression compared with CHC, cirrhotic and surrounding non-neoplastic liver tissues (P < 0.05). The plasma MIR17HG protein levels were positively correlated with tumor size (P = 0.001), stage (P = 0.001) and HCC histological grade (P = 0.002) and c-MYC (P = 0.001) and NF-kB expression (P = 0.015) and were inversely correlated with PTEN expression (P = 0.001). Conclusions: Activation of miR-17~92 cluster induced by c-MYC may play an important role in the development and progression of HCV-related HCC, possibly, through inhibition of PTEN and activation of NF-kB and could provide a potential therapeutic target for HCC. Circulating MIR17HG protein could be a useful non-invasive biomarker for the detection of HCC in chronic HCV infection.
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