فهرست مطالب

Journal of Seismology and Earthquake Engineering
Volume:19 Issue: 4, Winter 2017

  • تاریخ انتشار: 1396/08/29
  • تعداد عناوین: 6
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  • Ameneh Houshmandviki, Anooshiravan Ansari Pages 261-271
    The effect of interpolation function for describing spatial variations of slip on the fault surface is investigated using finite fault simulation. In analogy with h-p notion in finite element method, the effect of increasing the order of interpolation function and decreasing the size of elements is studied here. In this regard, the fault surface is discretized using different elements, namely, constant discontinuous elements with various sizes, and first order contentious elements with different sizes. In order of parameterization, a bilinear interpolation technique is introduced to represent variation of source parameters within the subfault area. To provide an objective basis for comparison, the September 28, 2004 Parkfield earthquake Mw 6.1 is considered and time-frequency, envelope-phase goodness-of-fit criteria is calculated to compare synthetic and observed waveforms quantitatively in time and frequency domains. It was revealed that by increasing the order of interpolation function, the overall consistency of observed and synthetic waveforms will increase, while the expense of computational analyses will also increase accordingly.
    Keywords: Interpolation, h-p notion, Parkfield earthquake, Goodness-of- fit, Finite fault simulation
  • Ali Shafiee, Rouzbeh Dabiri, Faradjollah Askari Pages 273-284
    A series of undrained resonant column, monotonic and cyclic triaxial tests was performed to investigate the effects of non-plastic fines on the dynamic properties of Firoozkooh sand. Specimens of sand-silt mixtures were prepared at different densities, and tested under various confining pressures. Test results revealed that shear modulus decreases with fines, and increases with relative density and confining pressure. Normalized shear modulus is not affected by fines, relative density and confining pressure, while damping ratio is affected by fines and confining pressure. Finally, field cyclic resistance ratios versus normalized shear wave velocity values are developed on the basis of cyclic triaxial and resonant column tests.
    Keywords: Firoozkooh sand, Non-plastic silt, Shear modulus, Damping ratio, Cyclic resistance, Shear wave velocity
  • Masoud Amelsakhi, Abdollah Sohrabi, Bidar, Arash Shareghi Pages 285-298
    This study aims to rigorously examine the influences of the vertically propagating recorded strong ground motions on the trapezoidal-shaped hills in different sizes and shape ratios. In order to generalize the results of the study, one-dimensional as well as two-dimensional analyses are conducted. Then, intended results are represented in dimensionless form as a result of which amplification ratio patterns are extracted and compared with each other in terms of displacement, velocity, and acceleration. Similarly, corresponding response spectra ratios are derived on significant points on hill-crest, hill-side, and beside of that, and juxtaposed in diagrams. Results of the assessment are put together with that of recent studies and predictions of the reliable codes. An adequate agreement between maximum values of amplification ratios obtained in time-domain analyses and spectral analyses makes us hopeful to think of connecting time-domain parameters with spectra-related ones to propose an accurate equation, which considers more effective variations regarding the topographic seismic effects and gives most reliable prediction. However, here, an equation has already been suggested to draw amplification ratio patterns on different points of the hill for a limited hillshape, dimension, media characterization and constitutive model. Comparing the estimations of the amplification ratio patterns using different methods proves that, considering potent parameters related to the time-domain and frequency-domain, the proposed equation is more efficient than the other codes.
    Keywords: Topographic effect, Time-domain amplification ratio, Spectral amplification ratio, Geotechnical earthquake engineering
  • Sayed Mohammad Motovali Emami, Majid Mohammadi, Paulo B. Lourenço Pages 299-311
    Equivalent compression strut is one of the most prevalent approaches recommended in seismic codes to simulate infill panels in the frames. The mechanical parameters of infilled frames, such as strength and stiffness, are controlled by material properties, thickness and width of equivalent strut. The strut width depends on the contact length between the infill and the frame. Previous studies have shown that the connection rigidity of the surrounding frame affects the contact length and consequently the response of infilled frame. Parametric finite element analyses have been carried out to investigate the influence of frame connection rigidity on the behavior of infill walls using ABAQUS environment. The finite element
    models were verified based on the results of experimental data. It is shown that the stiffness and strength of infill panel in pinned connection steel frame are 0.9 and 0.8 times of those in rigid connection frame, respectively. The results of parametric finite element analyses were validated using equivalent strut method. Moreover, it is shown that the equivalent diagonal struts in multi-bay frame have the same properties of strut in one-bay frames for both rigid and pinned connections ones.
    Keywords: Infill wall, Pinned connection frame, Equivalent strut model, Multi-bay infilled frame, ABAQUS, FEM
  • Sahand Jabini Asli, Hamed Saffari, Mohammad Javad Zahedi Pages 313-325
    The prediction of the seismic behavior of structures during earthquake has always been an important concern for earthquake and structural engineers. In addition to earthquakes, the behavior of soil and its effects on seismic responses of structure, also known as Soil-Structure Interaction (SSI), make this problem more complicated. For this purpose, today, many investigations are focusing on soil role in seismic behavior of structures. In this study, the seismic behavior of steel structures with various heights under the SSI effect have been studied. For this purpose, three steel structures including 9, 15 and 20 story frames were modeled using Opensees. Besides, their seismic behaviors under different base conditions including fixed base and on three different types of soil (B, C and D) under 11 bedrock earthquakes were also investigated using the direct method. The responses in two terms including story shear and story drift were also investigated.
    Keywords: Soil-Structure Interaction, Direct method, Moment resisting frame, Finite element, Opensees
  • Seyed Mehdi Zahrai, Alireza Heisami Pages 327-336
    Impact dampers are considered among passive control devices. Experimental and analytical research studies have shown that this group of nonlinear dampers has a better performance for reducing structural vibrations as compared to linear vibrating neutralizers. Tall building is a structure that is different from other buildings in design aspects, construction, and operation due to its height. Medium height and tall models are used in the present paper in order to compare the performance of impact dampers in tall buildings. In this study, seismic performance of tall buildings with impact dampers is evaluated by using SAP2000 software. The condition of tall buildings with impact dampers is subsequently introduced. In order to achieve more desirable results for tall buildings subjected to seismic vibration, the earthquake records applied to multi degree of freedom systems are selected from both near and far-field seismic events. This study aims to represent how the impact damper operates in tall buildings and to determine the best location for its installation in order to reduce the response of vibrating system. Using nonlinear time history analysis, structural elements have been investigated based on AISC360-10 regulation in the design process. Among the results obtained in this research, reduction in the response of multi-degree-of-freedom systems in vibration condition using impact damper placed on the top floor can be mentioned. Moreover, it was observed that the more the frame height and its number of spans, the better the effect of placing impact damper in a story close to the roof as compared to placing it
    Keywords: Nonlinear damper, Impact damper, Tall building, Near, far-field earthquakes, Numerical analysis