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Journal concessionaire
 Kharazmi University
Managing director
Seyed Mahmoud Fatemi Aghda, Professor
Ali Ghanbari, Professor
Ali Noorzad, Associate Professor
Fatemeh Torabi
ISSN: 2228-6837
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Showing 5 results for Massumi

S.a Hosseini , A Massumi ,
Volume 10, Issue 5 (2nd conferences on earthquake engineering (Alborz Province) 2016)

In seismic prone areas, earthquakes happen more than just main shocks which are happen with sequences of shocks include of different intensity of aftershocks. In technical documents, these kinds of several earthquakes are called mainshock-aftershock ground motions. In this study, seismic behavior of RC frame under mainshock-aftershock with different ratios of maximum acceleration of aftershock to maximum acceleration of mainshock was evaluated. In this paper, nonlinear time-history analysis of frame were performed under mainshock-aftershock sequences and then the residual interstory drift ratio for comparing response of frame under seismic sequences was evaluated. The results show that, residual interstory drift ratio of frame, related to intensity of aftershocks to mainshock and enhance of intensity of aftershock due to increase residual interstory drift ratio of frame. Although, growth of residual interstory drift ratio of top stories more significant than below stories of frame.

A Erfani , A Ghanbari , A Massumi ,
Volume 10, Issue 5 (2nd conferences on earthquake engineering (Alborz Province) 2016)

Previous earthquakes have shown that topographic irregularities have significant impacts on the site seismic response and increasing structural damage by amplifying seismic responses. Studies on seismic behavior of slope topographic have shown that dynamic response of free field and soil-structure system is severely on the influence of topography shape and soil properties. Angle and height of slope, frequency of excitation, nonlinear behavior of soil and depth of bedrock are other parameters that affect on the response of the entire system. Furthermore the studies have shown that presence of structure adjacent to slope is very effective on variation of seismic behavior pattern of this topography but these studies are very limited. In this study the effect of existing structure adjacent to slope to seismic behavior pattern of slope topography have been investigated. The parameters that have studied in this article comprise slope angle and frequency content of excitation. The results show that the presence of structure adjacent to the slope, causes an increase to the response of free field and transmitting maximum response to distance away from structure position.

Ali Massumi, Maryam Rahmati Selkisari,
Volume 11, Issue 3 (Vol. 11 No. 3 Autumn 2017 2018)

In recent decades many researchers have studied on the damage assessment of structures after a seismic event. To assess the damage of structures under an earthquake, it is so important to study the correlations between earthquake parameters and damages of the structures. A lot of seismic parameters have been defined by researchers to characterize an earthquake. Spectral parameters of an earthquake convey a variety of information about ground motion, so they can properly characterize an earthquake. Also a lot of damage indices were proposed by researchers to quantify the damage of the structures or to rank their vulnerability relative to each other. Park-Ang index is one of the best indices to describe the damage of a structure. In this paper, the correlations between spectral parameters of earthquakes and Park-Ang indices are studied. Three RC frames with different height are analyzed under far-fault earthquake records by nonlinear dynamic analyses. The correlations between spectral parameters and Park-Ang indices of the frames are calculated. The results show that in all the frames most of spectral parameters have strong correlations with damage intensity. In order to estimate the damage potential of an earthquake, some spectral parameters which have high correlations with damage intensity can be proper indices. Housner intensity, acceleration spectrum intensity and velocity spectrum intensity are shown to have strong correlations with damage intensity. In this paper, a new spectral parameter which has high correlation with damage intensity is achieved. 
Sassan Narimannejad, Alireza Jafari-Nedoshan, Ali Massumi, Abdollah Sohrabi-Bidar, Ali Ghanbari1,
Volume 12, Issue 2 (Vol. 12, No. 2, Summer 2018 2018)

Local site conditions considerably influence all characteristics of the ground strong motion including the domain, frequency content, and duration. The level of such an effect could be considered as a function of geometry, properties of the materials embedded in the underlying layers, the site topography, and properties of excitement. Site effect fall into two categories: a) the effect of the surface soft layers triggered by the shear velocity differences between the soil layers and b) the surface and subsurface topography effects that lead to the wave reflection and refraction based on the site geometry, and subsequently enhance the level of amplification.
Since most cities have been constructed in the vicinity of or on sedimentary basins, geotechnical earthquake engineering devotes particular attention to effects of the sedimentary basins. Basin edge curvature deposited with soft soils are capable to trap the body waves and generated surface waves within the deposit layers. Such waves could create stronger and lengthier vibrations than those estimated in a 1D analysis that assumes the shear waves to be vertically propagated.
Although critically important, the 2D effect of the site has not been included in seismic codes and standards of the world. This might be due to the fact that the site effect depends on a number of parameters such as the site geometry, the type of wave excitement, properties of the materials, etc. that in return make it almost out of the question to make predictions about the effect. This study was an effort to compare the responses of four sedimentary basins with hypothetical geometries of rectangular, trapezoidal, elliptical, and triangular shapes in order to examine the effect of the geometrical shape of the basin on its responses and the extent of the response sensitivity to the excitation frequency of the wave. The study assumed the edge to depth proportion to be both constant and equal in all four basins so that the effect of the geometrical shape could be equally examined and compared in all four basins.      
Material and methods
In order to validate the results of the sedimentary basin modeling, firstly, ABAQUS finite element software was used to create a free field motion of a semi-circular alluvium valley in accordance with Kamalian et al. (2006) and Moassesian and Darvinsky (1987).  Then, the results from the model were compared with those from the above mentioned studies. The following descriptions are to present the model in details.
To evaluate the geometrical effect of the sedimentary basin on its response, the authors relied on the software to examine four sedimentary basins with the fundamental frequency (2.04 Hz). The basins enjoyed rectangular, trapezoidal, elliptical, and triangular geometrical shapes with a constant edge to depth proportion (49m to 300m respectively). The implicit method was also applied to perform the dynamic analysis. The materials were all viscoelastic and homogeneous. The soil behavior/treatment model was considered to be of a linear nature.  The Rayleigh damping model was used to specify the damping level. The soil element was a plane strain and SV waves (the Ricker wavelet) were used for seismic loadings in a vertical dispersion. The side boundaries (right and left) of the model were of a combinational type (viscous and free field boundaries); the down side boundary was composed of viscous. To achieve higher levels of wave absorptions, heavy columns were used as the free filed columns.
Next, it was the time to conduct the 1D analysis of the site. Three waves were in use in order to examine the effect of the frequency content of the excitation load on the basin response: 1) a wave with the dominant frequency of 1Hz that was out of the frequency range of all basins (2.04 Hz), a second wave with the dominant frequency of 2Hz that was close to the fundamental frequency of all basins, and a third wave with the dominant frequency of 4Hz. The waves were applied to a 2Dmodel. The results were compared with those obtained from a 1Dmodel in terms of the timing.
Then, the basin responses to all three waves (1, 2, and 4 Hz) were subjected to an individual analysis in order to examine the sensitivity of each basin response to its geometrical shape. Results indicated that while the responses of the rectangular and trapezoidal basins were significantly more sensitive to the excitation frequencies, the elliptical and triangular basins showed more stable behaviors to such frequencies. The final stage of the study was dedicated to examine the site 2D effect during the ground motion.
Results and Conclusions
According to the results of the present study, it could be suggested that the geometrical shape of the sedimentary basin has a significant effect on the responses of the field of seismic waves and that it could result in so different responses from the ones attained after a 1D analysis of the site. In addition, the pattern of the seismic waves’ responses is highly dependent on the geometrical shape and the frequency content of the seismic load. Also, the location where the maximum horizontal acceleration occurs along with the sedimentary basin depends on the excitation wave and varies accordingly. Further, it could be suggested that the site 2D effect results in both considerable amplification and an increase in the length of ground motion.
The results of the 2D analysis showed remarkable differences with their 1D counterparts: a 1.45 larger response for the rectangular basin, a 1.28 larger response for the trapezoidal basin, a 1.22 larger response for the elliptical basin, and a 1.19 larger response for the triangular basin.
With the frequency of 1 Hz where the excitation frequency is out of the basin range (i.e. the excitation frequency is below the lowest frequency of basin), the sedimentary basin did not show any signs of amplification and chaos (unlike two other frequencies); instead, it was a cause for de-amplification.
The frequency of 2 Hz that is subject to resonance resulted in amplifications (absent in 1D analysis) and there are traces of a reduction in the acceleration responses near to the edges of the basins. The proportion of the amplification (in the center of the basins) in 2D to 1D analysis was 1.4 for the rectangular basin, 1.28 for the trapezoidal basin, 1.22 for the elliptical basin, and 1.15 for the triangular basin.
Dr. Seyed Hossein Hosseini Lavassani, Mr. Hamed Alizadeh, Pro. Ali Massumi,
Volume 16, Issue 1 (10-2022)

Many researches have been currently conducted on the effects of fault distance on structures revealing that their seismic response can differ according to their distance from the fault. Suspension bridges due to their long period and high flexibility can be more sensitive to this phenomenon, especially in vertical vibration. Since the engineers tend to use longer spans, the length factor should be studied more accurately. In this paper, the effects of length factor on the seismic response of the suspension bridge under near and far-fault ground motions were addressed. The Vincent Thomas and Golden Gate suspension bridges as short and long ones, respectively, are selected as the case studies. The seismic responses of two bridges under five main worldwide ground motions contained both near and far-fault ones, with the same peak ground’s acceleration, are evaluated. The results indicated that the response of both bridges to the near and far-fault ground motions are perfectly different. Short span suspension bridges are vulnerable to near-fault ground motions, whereas long span ones are completely susceptible to both near and far-fault ground motions, and by increasing the length of span, the sensitivity of bridge was increased against far-fault low frequency excitations. Also, maximum displacement responses of spans in both bridges did not increase by maximizing peak ground’s acceleration.

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نشریه زمین شناسی مهندسی Journal of Engineering Geology
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