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    • List of Articles Mehran Seyed Razzaghi

      • Open Access Article

        1 - Performance of industrial facilities and lifelines during the October 23rd, 2011 Van, Turkey Earthquake
        Kiarash Nasserasadi Mehran Seyed Razzaghi
        Damage to essential facilities (e.g. lifelines and industrial facilities) due to extreme loads may cause remarkable indirect impact as well as direct physical loss. Hence understanding seismic performance of essential facilities is very important in high seismic risk re More
        Damage to essential facilities (e.g. lifelines and industrial facilities) due to extreme loads may cause remarkable indirect impact as well as direct physical loss. Hence understanding seismic performance of essential facilities is very important in high seismic risk regions. On October 23, 2011 an earthquake of magnitude Mw7.2 occurred in Van province in eastern Turkey. Several damages occurred at industrial plants. Damage to equipment and buildings caused work abandon in some industrial plants. In this paper the observed damage to essential facilities such as transportation systems, silos and gas stations are presented. Manuscript profile
      • Open Access Article

        2 - Neural Prediction of Buckling Capacity of Stiffened Cylindrical Shells
        Mehran Seyed Razzaghi N. Rahmani
        Estimation of the nonlinear buckling capacity of thin walled shells is one of the most important aspects of structural mechanics. In this study the axial buckling load of 132 stiffened shells were numerically calculated. The applicability of artificial neural networks ( More
        Estimation of the nonlinear buckling capacity of thin walled shells is one of the most important aspects of structural mechanics. In this study the axial buckling load of 132 stiffened shells were numerically calculated. The applicability of artificial neural networks (ANN) in predicting the buckling capacity of vertically stiffened shells was studied. To this end feed forward (FF) multi-layer perceptron (MLP) neural networks were used. The shell height (H), shell diameter (D), shell thickness (t), width (b), thickness of stiffeners (ts), and unstiffened length of the cylinder (l) were considered as the input vector; the relative buckling capacities of stiffened shells to unstiffened ones (Pcr/Pcr0) were considered as the output of the MLP networks. The back propagation algorithm was used to train the networks. Different structures of ANN were trained by 100 of the outputs of the numerical analysis and tested by 32 remains. The best ANN structure was selected based on the mean square error (MSE) and correlation coefficient (R2). The results of this study revealed that MLP neural networks can remarkably predict the axial capacity of stiffened shells. A parametric study on the buckling loads of the stiffened shells was performed by using the neural prediction and FEM. Manuscript profile
      • Open Access Article

        3 - The Behavior of Type of RC Column-to-Steel Beam Connections and Scrutiny Of Behavior Coefficients
        Hassan Aghabarati Mehran Seyed Razzaghi Kavian Parhizkar
        (RCS) frames which are systems that dwell of concrete columns and steel beams , by optimizing the act of compressive strength of concrete and bending strength of steel due to not only a decrease in building weight in comparison to concrete structures but also having a b More
        (RCS) frames which are systems that dwell of concrete columns and steel beams , by optimizing the act of compressive strength of concrete and bending strength of steel due to not only a decrease in building weight in comparison to concrete structures but also having a better action in long spans frames . In this paper for analysis RCS behavior, a category of nonlinear Push Over analyses were achieved on typical low to mid-rise RCS buildings. 1,2,3,4 and 5 span frames with span length of 6 meters in 1 to 5 stories were elected for this project. The systems were controlled by using FEMA-273 and ATC-40 codes. Manuscript profile
      • Open Access Article

        4 - Probabilistic Evaluation of Seismic Performance of RC Bridges in Iran
        Mehran Seyed Razzaghi M. Safarkhanlou
        Many existing bridges were designed without adequate consideration of seismic risk. The full or partial collapse of even one major bridge in a city or community would have destroying results. There has been focuses on developing fragility-based seismic vulnerability of More
        Many existing bridges were designed without adequate consideration of seismic risk. The full or partial collapse of even one major bridge in a city or community would have destroying results. There has been focuses on developing fragility-based seismic vulnerability of existing usual bridges in Iran or support decision making on seismic upgrade. This article focuses on developing performance based seismic fragility curves for typical RC bridges in Iran. Ground motions compatible with the seismic hazard were used as input excitations for bridge vulnerability assessment. The fragility curves thus developed will quantify the vulnerability of existing RC bridges and help in proper decision making to increase the safety for humans and the serviceability of essential facilities. Results obtained from this study show that the properties of materials have a significant effect on the damage probability of the bridges. The findings can serve as a guide to declare the impact of seismic vulnerability on the bridges. Manuscript profile
      • Open Access Article

        5 - Buckling of Cylindrical Steel Shells with Random Imperfections due to Global Shear
        Nima Rahmani Mehran S. Razzaghi Mahmoud Hosseini
        This study aims to investigate the effects of geometric imperfections on buckling of thin cylindrical shells due to global shear. To this end, more than 320 finite element models of cylindrical shells with different diameter to thickness ratios were prepared. Random imp More
        This study aims to investigate the effects of geometric imperfections on buckling of thin cylindrical shells due to global shear. To this end, more than 320 finite element models of cylindrical shells with different diameter to thickness ratios were prepared. Random imperfections with different amplitudes were applied to numerical models. The results revealed that global buckling of cylindrical shells are susceptible to imperfection patterns. It was also shown that Yamaki’s expression can be considered as upper band for plastic shear buckling of thin cylindrical shells. Manuscript profile
      • Open Access Article

        6 - The Effect of Compressive Strength Reduction of Column Section Expose due to Freezing-Thawing Cycles on the Seismic Performance of Bridges
        Saeideh Alsadat Mousavi Mehran Seyed Razzaghi
        One of the serious damages of tremendous earthquakes is the damage to bridges as the major components in an arterial road network, as relief operation is interrupted following cutting roads. Regardless of the magnitude and severity of an earthquake, other factors are al More
        One of the serious damages of tremendous earthquakes is the damage to bridges as the major components in an arterial road network, as relief operation is interrupted following cutting roads. Regardless of the magnitude and severity of an earthquake, other factors are also important in the strength and seismic performance of concrete bridges. Freezing-thawing cycles are among the factors, which erode the piers of concrete bridges over time. Therefore, it is necessary to evaluate the seismic vulnerability of bridges for future designs.This research aims at discussing the effect of freeze-thaw cycles on the seismic performance of concrete bridges using fragilitycurves. Fragility curves express the conditional probability to reach or exceed a level of damage as a function of ground motion parameters. The curves have been developed analytically using a probabilistic method. Ground motion parameter, peak ground acceleration, structural criterion, and relative displacement of piles were considered. The non-linear time history analysis in OpenSees was used for demand determination. The curves were drawn for the slight, moderate, and extensive damage levels in two modes of before and after damage caused by thawing and freezing, i.e. the mode in which the compressive strength of column section expose reduced. With respect to the fragility curves, the strength reduction increases bridge vulnerability, especially on slight damage levels. Comparing with the cyclic curves of the most vulnerable column in two modes of before and after the damage showed that energy absorption capacity lowered with the expose compressive strength reducing. Manuscript profile