Influence of near-fault ground motions characteristics on elastic seismic response of asymmetric buildings

Tabatabaei, R.,Saffari, H. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.4

The elastic seismic response of plan-asymmetric multi storey steel-frame buildings is investigated under earthquake loading with particular emphasis on forward-rupture directivity and fling records. Three asymmetric building systems are generated with different torsional stiffness and varying static eccentricity. The structural characteristic of these systems are designed according to UBC 97 code and their seismic responses subjected to a set of earthquake records are obtained from the response history analysis (RHA) as well as the linear static analysis (LSA). It is shown that, the elastic torsional response is influenced by the intensity of near-fault ground motions with different energy contents. In the extreme case of very strong earthquakes, the behaviour of torsionally stiff buildings and torsionally flexible buildings may differ substantially due to the fact that the displacement envelope of the deck depends on ground motion characteristics.

Influence of near-fault ground motions characteristics on elastic seismic response of asymmetric buildings

R. Tabatabaei,H. Saffari 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.4

The elastic seismic response of plan-asymmetric multi storey steel-frame buildings is investigated under earthquake loading with particular emphasis on forward-rupture directivity and fling records. Three asymmetric building systems are generated with different torsional stiffness and varying static eccentricity. The structural characteristic of these systems are designed according to UBC 97 code and their seismic responses subjected to a set of earthquake records are obtained from the response history analysis (RHA) as well as the linear static analysis (LSA). It is shown that, the elastic torsional response is influenced by the intensity of near-fault ground motions with different energy contents. In the extreme case of very strong earthquakes, the behaviour of torsionally stiff buildings and torsionally flexible buildings may differ substantially due to the fact that the displacement envelope of the deck depends on ground motion characteristics.

Demonstration of Torsional Behaviour Using Vibration-based Single-storey Model with Double Eccentricities

R. Tabatabaei,H. Saffari 대한토목학회 2010 KSCE JOURNAL OF CIVIL ENGINEERING Vol.14 No.4

The use of single-storey schemes appears necessary in order to investigate lateral-torsional coupling in building structures. In this paper, the torsional behaviour of an eccentric single-storey system based on undamped free vibration analysis has been investigated with particular emphasis on double eccentricities. An eccentricity between the center of rigidity and the center of mass in a building system causes the different torsional behaviour during a seismic loading. This approach reveals clearly how the double eccentric system behaves in relationship with the natural frequencies and modes and translational or torsional motion of the modeling system. From the parametric analysis of such an approach the determinative role of the distance from the center of mass to the center of rotation corresponding to the torsional and lateral stiffness ratio of the system becomes an obvious means of defining the torsional behaviour. From the outcome of applying the model, the building model can be classified as Torsionally Stiff (TS) and Torsionally Flexible (TF) based on the way the model has been configured in terms of the loci of the centers of rotation.

Large strain analysis of two-dimensional frames by the normal flow algorithm

Tabatabaei, R.,Saffari, H 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.36 No.5

Nonlinear equations of structures are generally solved numerically by the iterative solution of linear equations. However, this iterative procedure diverges when the tangent stiffness is ill-conditioned which occurs near limit points. In other words, a major challenge with simple iterative methods is failure caused by a singular or near singular Jacobian matrix. In this paper, using the Newton-Raphson algorithm based on Davidenko’s equations, the iterations can traverse the limit point without difficulty. It is argued that the propose algorithm may be both more computationally efficient and more robust compared to the other algorithm when tracing path through severe nonlinearities such as those associated with structural collapse. Two frames are analyzed using the proposed algorithm and the results are compared with the previous methods. The ability of the proposed method, particularly for tracing the limit points, is demonstrated by those numerical examples.

Pyruvate Dehydrogenase Complex and Glucose Oxidation as a Therapeutic Target in Diabetic Heart Disease

Tabatabaei Dakhili Seyed Amirhossein,Amanda A. Greenwell,John R. Ussher 한국지질동맥경화학회 2023 지질·동맥경화학회지 Vol.12 No.1

Diabetic cardiomyopathy was originally described as the presence of ventricular dysfunction in the absence of coronary artery disease and/or hypertension. It is characterized by diastolic dysfunction and is more prevalent in people with diabetes than originally realized, leading to the suggestion in the field that it simply be referred to as diabetic heart disease. While there are currently no approved therapies for diabetic heart disease, a multitude of studies clearly demonstrate that it is characterized by several disturbances in myocardial energy metabolism. One of the most prominent changes in myocardial energy metabolism in diabetes is a robust impairment in glucose oxidation. Herein we will describe the mechanisms responsible for the diabetes-induced decline in myocardial glucose oxidation, and the pharmacological approaches that have been pursued to correct this metabolic disorder. With surmounting evidence that stimulating myocardial glucose oxidation can alleviate diastolic dysfunction and other pathologies associated with diabetic heart disease, this may also represent a novel strategy for decreasing the prevalence of heart failure with preserved ejection fraction in the diabetic population.

Bridge-type structures analysis using RMP concept considering shear and bending flexibility

Mahmoud-Reza Hosseini-Tabatabaei,Mohmmad Rezaiee-Pajand,Mahmoud R. Mollaeinia 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.74 No.2

Researchers have elaborated several accurate methods to calculate member-end rotations or moments, directly, for bridge-type structures. Recently, the concept of rotation and moment propagation (RMP) has been presented considering bending flexibility, only. Through which, in spite of moment distribution method, all joints are free resulting in rotation and moment emit throughout the structure similar to wave motion. This paper proposes a new set of closed-form equations to calculate member-end rotation or moment, directly, comprising both shear and bending flexibility. Furthermore, the authors program the algorithm of Timoshenko beam theory cooperated with the finite element. Several numerical examples, conducted on the procedures, show that the method is superior in not only the dominant algorithm but also the preciseness of results.

Effect of Dietary Cation-Anion Difference during Prepartum and Postpartum Periods on Performance, Blood and Urine Minerals Status of Holstein Dairy Cow

Razzaghi, A.,Aliarabi, H.,Tabatabaei, M.M.,Saki, A.A.,Valizadeh, R.,Zamani, P. Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.4

Twenty four periparturient cows were used to determine the effects of DCAD on acid-base balance, plasma and urine mineral concentrations, health status, and subsequent lactation performance. Each group of 12 cows received either a diet containing -100 DCAD or +100 DCAD for 21 d prepartum. Both anionic and cationic groups were divided into two groups, one received a +200 DCAD and the other +400 DCAD diet for 60 d postpartum. Prepartum reduction of DCAD decreased DMI, urinary and blood pH, urinary concentrations of Na or K and increased plasma and urinary Ca, Mg, Cl and S. Also cows fed -100 DCAD diet consumed the most dry matter in the first 60 d after calving. Postpartum +400 DCAD increased milk fat and total solid percentages, urinary and blood pH and urinary Na and K concentrations, but urinary Ca, P, Cl and S contents decreased. Greater DMI, FCM yields were observed in cows fed a diet of +400 DCAD than +200 DCAD. No case of milk fever occurred for any diets but feeding with a negative DCAD diet reduced placenta expulsion time. In conclusion, feeding negative DCAD in late gestation period and high DCAD in early lactation improves performance and productivity of dairy cows.