In this paper, the long-term crustal flow of the Iranian Plateau is computed using a kinematic finite-element model (NeoKinema software). Based on the iterated weighted least squares method, the models are fitted to the newest data set of Iran including updated fault traces, geologic fault offset rates, geodetic benchmark velocities, principal stress directions, and velocity boundary conditions. We are successful to find the best kinematic model, in which geological slip rates, geodetic velocities, and interpolated stress directions are fitted at levels of 0.35, 1.0, and 1.0 datum standard deviation, respectively. The best fitted model, for the first time, provides long-term fault slip rates, velocity, and anelastic strain rate field in the Iranian Plateau from all available kinematic data. In order to verify the model, the estimates of fault slip rates are compared to slip rates from merely analyzing geodetic benchmark velocities or paleoseismological studies or published geological rates which have not been used in the model. Our estimated rates are all in the range of geodetic rates and are even more consistent with geological rates than previous GPS-based estimates. Using the selected model, long-term average seismicity maps and long-term moment rates are produced on the basis of the SHIFT hypothesis and previous global calibrations. Our kinematic model also provides a new constraint on ratio of seismic deformation to total deformation for different seismic zones of Iran. The resulting slip rates and the proposed seismic fraction of deformation provide the necessary input data for future time-dependent hazard studies in Iran. Moreover, spatial distribution and total number of strong (M > 6) and major (M > 7) earthquakes, which dominate the seismic hazard, are all compatible with the regional seismic catalog.

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In this article, an innovative base isolation system based on steel–polytetrafluoroethylene sliding bearings equipped with shape memory alloy is proposed. This isolation system employs superelastic Ni–Ti alloy cables as recentering components and dissipates input energy through the friction and additional damping of shape memory alloy. As a case study, Izadkhast Bridge, the longest railway bridge in Iran, is considered and fitted with the proposed system. A three-dimensional nonlinear finite element model of the bridge is developed and time history analyses for various earthquake records are conducted. The results demonstrate that the proposed isolation system can effectively improve the bridge response quantities. Moreover, equipping the sliding bearings with shape memory alloy efficiently reduces permanent deck displacement of the base-isolated bridge. This study reveals that shape memory alloy cables mostly work as recentering elements with regard to the minimal damping capacity of shape memory alloy cables. In addition, sensitivity analyses on environmental temperature reveals that mechanical behavior of shape memory alloy on minimum probable temperature should be considered in design procedure. Regarding the financial and functional aspects, using minimum cross-sectional area and length of shape memory alloy cables is appropriate. Moreover, the geometric characteristics of shape memory alloy cables should be selected, so that shape memory alloy strain is being limited to the recoverable range (up to 8%).

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This paper captures the behavior of micropiled rafts in power transmission line tower foundations in cohesive soil, concentrating on their uplift performance whether due to the tower position along the line or under wind loading conditions. In this regard, first a number of micropiles were driven into the ground of a project site at the ParehSar power plant, Gilan, Iran. Compression and uplift loading tests were conducted according to relevant standards. On the basis of the field data, a three-dimensional finite element model was developed and subsequently calibrated and verified. The behavior of micropiled rafts subjected to uplift, which is a typical type of loading in foundations of 230 kV four-circuit lattice towers, was then studied by means of this model in terms of a wide-ranging parametric study. In the sensitivity analyses, the impacts of various parameters, such as micropile spacing-to-diameter (s/d) and length-to-diameter (l/d) ratios along with undrained shear strength of the soil, on the uplift capacity of an individual micropile within and out of the group were investigated. Furthermore, interaction factors were computed based on diverse values for undrained shear strength of the soil, s/d ratio, l/d ratio, and grout–soil adhesion. From design and analysis perspectives, the finite element method (FEM) outputs revealed that the efficiency coefficient of micropiled rafts during uplift can be considered equal to one. Moreover, it was found that not only does the behavior of micropiles affect the neighboring micropiles immediately adjacent to the loaded one, but it also influences those in further rows, the result of which would be considering their significance as well.

The seismic activity rate is one of the most significant factors in seismic hazard modeling. Although it is usually estimated from observed seismicity, a complete picture of the possible earthquakes is not always available since catalogs of the observed earthquakes are short and incomplete. Long-term physics-based numerical simulations, providing a comprehensive range of earthquakes, are a decent way to overcome such deficiency. With this contribution, we built a seismic hazard model for the Alborz region, Iran, using a long-term physics-based synthetic earthquake catalog, enriched with the additional consideration of background seismicity derived from a deformation model. 200,000 yr synthetic catalogs for the Alborz region, Iran, are used and validated by considering the recurrence time of large-magnitude events estimated from the paleoseismological investigation on individual faults. The magnitude–frequency distribution (MFD) from the synthetic earthquake catalog is then compared with the MFD based on observation, which overall indicates good compatibility, although there are discrepancies for some faults. The estimated peak ground acceleration (PGA) for the Alborz region varies in the ranges of 0.16–0.52g and 0.27–1.0g for 10% and 2% probability of exceedance in 50 yr, respectively. The absolute natural logarithm differences averaged across the region are ∼0.21, corresponding to an average of 23% difference in PGA values in comparison with the most up-to-date observed-based hazard model. Hazard curves for several populated cities are also presented and compared with the other independent estimates. The proposed procedure could be an alternative approach to evaluate seismic hazard for a seismically active region, in particular for those without a complete catalog of observed earthquakes.