Journal of Seismology and Earthquake Engineering
Volume:18 Issue: 1, Spring 2016

114 three-component strong motion records from 2012 Ahar-Varzaghan double earthquakes (Mw=6.5, 6.3) are used to study the apparent source spectra of these two events. For this purpose, all the known effects of local site and travel path were deconvolved from the observed spectra. As of path effects (attenuation model), two models are considered: 1) a model developed by the authors in an earlier study with the geometrical spreading form of R-0.9 at close distances, 2) a model developed in this study in which the geometrical spreading has the more conventional form of R-1 at close distances. These two models have very similar associated Q factors, as the Q factor is more affected by the rate of geometrical spreading at longer distances. It is observed that the inferred source spectrum (particularly Brune stress drop) depends strongly on the considered attenuation model. For the studied events, the apparent observed source spectra for vertical and horizontal components show overall similarity, with horizontal component having bigger scatter and higher fluctuations. The apparent source spectrum of the first event almost perfectly matches the well-known Brune model; whereas the second event is a fair match to the Brune model and is better represented by a double corner frequency model. Out of four double-corner frequency models of source spectra where evaluated here, only the recently developed generalized double-corner-frequency model can successfully reproduce the observed ground motions; the other three lack flexibility in matching the high-frequency spectral level.

Tehran, the capital of Iran, is located in the southern part of Alborz mountains in north of Iran, which is an earthquake prone area. The recent developments in Earthquake Early Warning Systems (EEWS) encourage its application for seismic hazard mitigation, especially in mega-cities like Tehran. An effort was made here to develop the necessary relations and an algorithm for EEWS based on the initial few seconds of the P-wave arrival. For this purpose, a total of 654 accelerograms recorded by Road, Housing and Urban Development Research Center (BHRC) in Alborz region with the magnitude range of 4.8 to 6.5 in a period of 1995 to 2013 was employed. Among several parameters conventionally used for EEWS, the average ground motion period, peak displacement and their multiplications in a three-second time window from the beginning of an earthquake record were used to introduce the new magnitude scaling relations for Alborz region. The robust correlation between the estimated tc, Pd , and tc×Pd with the magnitude were used to validate their accuracy and application for EEWS. Furthermore, the Pd value of 0.3 (cm) and tc×Pd value of 1 were found to be the good indicators to separate earthquakes into non-destructive and destructive. The developed relations were also compared with those given by Wu and Kanamori (2008), and Heidari et al. (2013). The comparisons show good agreements with the Wu and Kanamori's relations, and differ with the one given by Heidari et al. This difference was attributed to the employed data by Heidari et al., which were limited to the magnitudes lower than 4.6. Finally, the outcomes were used to present a new algorithm for EEWS in Alborz region.

Sloshing Wave Impact Force (SWIF) caused by liquid motion during seismic excitations is investigated in this paper. When the freeboard is insufficient, the liquid waves collide to the tank roof on which uplift forces are produced. Due to the complication of sloshing impaction, there is no comprehensive investigation that can clarify the various aspect of this phenomenon. Therefore, most of standards don’t recommend any method to evaluate SWIF. Alternatively, the main approach of related codes and standards is to suggest a required freeboard in order to prevent collision of sloshing wave to the tank roof instead of evaluating the SWIF. However, suggested freeboard is too high to meet economic considerations in some cases. Therefore, the impact forces should be reasonably evaluated based on the experimental measurements and analytical solutions. An experimental investigation has been implemented to clarify the influence of various geometrical parameters on the impact roof pressure and force values of a rectangular tank. A series of shaking table tests are conducted for a partially filled rectangular tank under harmonic and different earthquake excitations. The experimental measurements for SWIF are compared with those recommended by code provisions and the effects of various parameters on SWIF are discussed.

Previous researches have demonstrated that the effects of earthquake vertical component on main structural elements of bridges are very noticeable in near-fault seismic events. In the near distances of seismic source (D

Safety is a primary consideration in any building. There are many risk factors which can cause casualties such as earthquake and fire. An important consideration in an emergency situation is the evacuation of people. This is of great importance when a large number of people are in confined spaces such as mosques and subway stations. To evaluate the evacuation of a place, an effective way is simulation. In this paper, as a case study, we simulate the evacuation behavior of the mosque of Azarbaijan Shahid Madani University (ASMU) using Distinct Element Method (DEM) in which an analysis of the position of each person can be computed step by step by solving the equation of motion. Four cases with different number and width of exits are considered, and evacuation behavior including evacuation time, density on exits, and flow rate are estimated quantitatively. Evacuation time is calculated to be 591, 156, 138 and 114 sec for cases 1 to 4, respectively. Density on exit 1 is equal to 4.5 (person/m2) for all four cases, and onexit 2 is calculated to be 4.23, 2.4, 2.4 and 1.47 (person/m2), for cases 1 to 4, respectively. As results show exit widths and number of exits have great influences on evacuation behavior. It is recommended that before construction of public buildings, evacuation simulations to achieve optimum evacuation behavior to be done.

Intensity is one of the useful information in extract earthquake analyzing of a region; then, preparing a complete dataset of them is necessary for each region. One of the best intensity information of the most historical and several instrumental earthquakes in Iran (from year 658 to 1979) was reported in an intensity scale with five degrees. There are also several earthquakes with reported intensity information in other three 12-degree intensity scales. Intensity values of these earthquakes could be more useful, if they are converted to a uniform scale, especially in a recent 12-degree intensity scale. In this study, the intensity values were re-estimated for the earthquakes with different reports of intensity. These estimations were performed based on the definition of both the European Macroseismic Scale to consider the building damages and Environmental Seismic Intensity Scale to consider environment effects.Orthogonal Regression was also selected to estimate the relationships between different reported intensity scales (0.61