In this study, an attempt is made to predict effective porosity in one of the oil fields in the Persian Gulf by designing a probablistic neural network (PNN) and simultanusely making use of SEISMIC attributes and effective porosity logs in the reservoir window. This was done by deriving a multiattribute transformation between an optimum subset of SEISMIC attributes and the effective porosity logs.The geophysical data used in this study consist of 3D SEISMIC pre-stack time migrated (PSTM) data with 12.5*12.5 m grid size and a 4 ms sampling rate. The length of the SEISMIC traces are two seconds. Well logs of five vertical wells in the study area, including Sonic (DT), Density (RHOB), Effective Porosity (PHIE) and SEISMIC Well Velocity Surveys (Check Shots), were used. The reservoir layer is a Mishrif member of the Sarvak formation with Cretaceous age, which is common in oil reservoirs in the Persian Gulf. The top of the Mishrif is adjusted with the Middle Turonian Unconformity and covered with shaley Laffan formation. The Mishrif Reservoir in study area contains two reservoir zones. The lower zone with higher clay content is separate from the upper zone. The upper zone consists of clean limesone with better reservoir properties. SEISMIC traces close to the well locations were used to generate SEISMIC attributes. Effective porosity logs at the reservoir area were the target logs in this study.The designed neural network consists of one input layer, one hidden layer with four processing units (neuron), and one output layer with one neuron. In order to prepare training samples for the neural network, PHIE logs were converted to time domain using a time-depth relationship calculated from the DT logs and check shot curves for each well location. Subsequently, these logs were filtered (using a Hanning filter with 4 ms length) and resampled with SEISMIC sampling rate (4 ms). Finally, a set of SEISMIC attributes, including sixteen sample-based SEISMIC attributes, were generated using HRS software. Training samples in this study consisted of 57 samples (selected SEISMIC attributes and their related effective porosity from PHIE logs in the time domain). For training the network, the samples were divided into three data sets: the training samples, cross validation samples and testing samples. The training data were used for adjusting the weights of the network; the cross validation data were used to prevent overtraining theneural network; and the testing data were used to ensure generalizabillity of the network output.A forward stepwise regression process was used to determine an optimum subset of attributes for use in the training of the neural networks. The optimum subset of attributes in this study consists of the Dominant Frequency, Amplitude Weighted Frequency, Integrated Absolute Amplitude and Filter 45-60 Hz.After the network was trained using training and cross validation data sets, it was used to predict the testing data. The results show a good correlation between real and predicted data, with 92% correlation. Finally, in order to attain a better generalization of the network, testing data sets were inserted to trained data and the network was trained again. This network was then used to predict effective porosity in well locations which increased the correlation coefficient to 95%. This study shows the ability of the PNN networks to predict effective porosity even with a paucity of training examplares.

Progressive collapse studies generally assess the performance of the structure under gravity and blast loads, while earthquakes may also lead to the progressive collapse of a damaged structure. In this study, the progressive collapse response of concentrically braced dual systems with steel moment-resisting frames was assessed under SEISMIC loads through pushover analysis using triangular and uniform lateral load patterns. Two different bracing types (X and inverted V braces) were considered, and their performances were compared under different lateral load patterns using the nonlinear static alternate path method recommended in the Unified Facilities Criteria (UFC) guideline. Eventually, the SEISMIC progressive collapse resistance of models was compared to their progressive collapse response under gravity loads. These studies showed that models under the SEISMIC progressive collapse loads satisfied UFC acceptance criteria and limited rehabilitation objective. The structures had better performance under SEISMIC progressive collapse than models under gravity loads because of more resistance, ductility, suitable load redistribution, and more structural elements that participated in load redistribution. Furthermore, despite studies on progressive collapse under gravity loads, the dual system with X braces showed better progressive collapse performance (more resistance, residual reserve strength ratio and ductility) under SEISMIC loads than the model with inverted V braces.

Increasing number of SEISMICally isolated structures mostly in SEISMIC-prone regions of the world has raised a concern on SEISMIC performance of these structures in severe earthquake ground motions. On one hand, base-isolated buildings should have a clear certain gap with adjacent structures to avoid pounding; otherwise developed SEISMIC force and displacement demands during impact with neighboring buildings or surrounding moat walls may be far beyond the capacity of the superstructure. In this case, the advantage of using base-isolation technology over traditional SEISMIC design may be totally lost. On the other hand, considering the high cost of lands and other urban limitations do not allow for large SEISMIC gaps to completely eliminate the risk of pounding. Moreover, isolation hardwares should remain stable under vertical loads at their maximum horizontal displacement demand under maximum considered earthquake motion. This results in expensive isolation devices that may prevent the use of isolation technology for a wide range of residential constructions. Additionally, the structural performance level of base-isolated buildings has a sharp change from immediate occupancy for moderate SEISMIC hazard levels to collapse prevention for the large ones. Consequently, structural elements of the superstructure usually do not experience damage-control performance levels. Aforementioned performance objectives may not be compliant with the performance goals considered for residential buildings with normal importance. This study aims to evaluate SEISMIC performance of base-isolated buildings with insufficient SEISMIC gaps that do not conform to minimum codified gap requirements. A wide range of isolated and fixed-base elastic superstructures has been subjected to analytical near field pulse-type motions to evaluate SEISMIC demands in the superstructure during impact with retaining walls. Different values for stiffness of moat walls has been considered with a stereomechanical impact model. The results of the parametric study show that the developed SEISMIC demands in the superstructure depends on the pulse duration, gap size and the ratio of the isolated period to the fixed-base period as well as the moat wall stiffness. As a conclusion, this study shows that by using available gap sizes and utilizing lower cost isolation devices with a smaller displacement capacity compared with the current code-based design requirements, a more economical performance-based SEISMIC design for base-isolated structures is achievable adopting a more gradual transition from immediate occupancy performance level to the collapse prevention one.

In this paper, the results of study on SEISMIC isolated buildings and effects of SEISMIC gaps between such buildings and adjacent buildings during earthquake have been presented. The importance of this study can be explained as, the results can be used to evaluate the effects of SEISMIC gap between structures which are subject to earthquake. Statistic information has been obtained by analyzing buildings with three, five and seven stories that were subjected to 20 earthquake records. Gaps among buildings changed based on characteristic of them with base isolation system; it can give us a better point. Each of structures was analyzed under the selected records and it was investigated effect of impact between them during earthquake on SEISMIC demands. In addition for studying effects of pounding on SEISMIC demand in structures with base isolated system, 540 nonlinear time history analysis was performed. At the end we suggested a simple and effective equation that can reduce effects of pounding on adjacent buildings.

Historical background and instrumentally located earthquakes as well as the geological evidences all suggest that Alborz region in northern Iran is one of the SEISMICally active regions in the Middle East. In 1996, as a part of national SEISMIC network, the Geophysics Institute of Tehran University deployed a telemetric SEISMIC network in Alborz region mainly to monitor local earthquakes. Relying on the records obtained during 1996-2005, several SEISMICally active areas with the following aspects could be recognized. The epicenters of local earthquakes are in good agreement with the location of major faults as well as the regional tectonic settings. The distribution of earthquakes in eastern and western parts of the region is consistent with the related major faults. A kind of SEISMIC quiescence exists in the central part of the Alborz around the Tehran city. A similar situation could be observed along the south eastern extension of Rudbar fault system. Most of the recorded earthquakes have shallow depths indicating that the SEISMIC activity is mainly taking place in upper crust and the seismogenic layer has a thickness of about 20 km. Taking into account the historical background and the present situation, the occurrence of a major earthquake in Alborz in the vicinity of Tehran is not far from expectation.

SEISMIC tomography is an imaging technique which creates maps of subsurface elastic properties such as P/S wave velocity, density and attenuation, based on observed seismograms and use of sophisticated inversion algorithms. Amongst different acquisition geometries, SEISMIC cross-hole tomography has a special position in geophysical surveys with many applications in hydrocarbons, coal and other minerals exploration and engineering purposes investigations related to constructions. Main goal of these studies is obtaining precise information about the earth structure (layers structure, impedance of layers, faults and fractures) or anomalies (objects, pipes, voids).Travel time tomography is a conventional approach to convert special phase of waveform travel times (such as P or S wave arrivals) to corresponding parameters. Low computational effort is needed to perform travel time tomography, but the results suffer from the lack of high resolution. SEISMIC waveform tomography is an efficient tool for high resolution imaging of complex geological structures and has been widely used by researchers in the field of exploration seismology. As waveform tomography exploits waveforms, in addition to travel times, it has superior resolution comparing to travel time tomography but its computational complexities have limited its everyday use in real world applications.In this study we focus on application of waveform tomography in an engineering purpose SEISMIC cross-hole study. Our approach relies on solution of acoustic wave equation in frequency domain and minimizing residual of calculated wave field and observed seismograms. Frequency domain approach lets simultaneous sources modeling and implementing frequency dependent absorption mechanisms. This approach leads to a large system of equations. To solve the large system of equations sparse direct solvers can be used. The mixed-grid finite-difference used to discretize continuous second order hyperbolic acoustic wave equation. Although elastic modeling is more the realistic and near to observed data, most researchers prefer to use acoustic wave equation instead of elastic one due to lower computational costs. Instead, we pre-process the observed data to increase comparability of observations and modeling. These pre-processing include suppressing phases cannot be explained by acoustic modeling such as S waves or Rayleigh waves or scaling seismograms to take into account amplitude vs. offset effects in acoustic and elastic cases. Waveform tomography is very a nonlinear problem with a very rugged cost function. To overcome this nonlinearity, we solve the problem using hierarchical approaches. We start inversion from low frequency components, where the cost function is smoother, and then proceed to higher components. Lower frequency inversion results have been used as initial velocity model for higher frequency inversion.A synthetic example has been used to test the performance of the algorithm in the absence and presence of noise. As the results show the performance of current waveform tomography algorithm decreases in case of noisy data, which implies the importance of denoising before inversion and/or employing regularization. Another strategy which helps to control noise issue is simultaneous inversion of frequency components in different groups, as showed in real data example. Lastly a real cross-hole dataset acquired for engineering purposes has been studied. The travel time tomography result is used as starting model for waveform tomography. The results of waveform tomography are in agreement with down hole measurements.

As a key point in main roads and railways of country, Andimeshk city has always have strategic situation in Khuzestan province and even Iran. On the other hand, most evidences indicate that this city is located in SEISMIC area and the incidence of a massive earthquake could impose huge losses on Iran economy. Considering this background, the aim of this study is to perform SEISMIC hazard analysis in Andimeshk territory and precisely evaluate the vulnerability of the buildings and structures in this city. To this end, the extreme risk curve was obtained using probability analysis, then the buildings were investigated in four types in order to identify the vulnerability curves in three levels. By the combination of risk curve and vulnerability curves the rate of vulnerability of Andimeshk buildings can be evaluated quantitatively. The results of this study show that the SEISMIC hazard level in Andimeshk city is relatively high and the base acceleration is equal to 0/325g and even more than the proposed rate in the standard 2800. Although there is no considerable concern regarding concrete buildings, the collapse of ancient and traditional buildings which are calculated 80 to 155 years is very challenging. In conclusion, the results indicate that a 20-year period might be suggested as a short chance to preserve the city.

Isolating the earth structures such as retaining walls, bridge abutments and buried pipes using the compressible materials is a novel solution to reduce the lateral earth pressure. In this technique, a layer of the compressible material with relatively small stiffness and limited thickness is implemented between the retaining wall and the backfill. This material acts as a SEISMIC buffer due to its high compressibility, which absorbs the excess dynamic earth pressure significantly and attenuates the transmitted force to the retaining structure. Choosing the appropriate materials for construction of SEISMIC buffers is based on their physical and mechanical properties as well as cost-effective considerations. Most of the previous studies were focused on some specific materials such as expanded polystyrene (EPS) foam blocks and tire chips. This paper investigated the performance of polymeric SEISMIC buffers made from Polyurethane (PU) foam on SEISMIC response of non-yielding retaining walls. PU foam has appropriate properties and eliminates some of limitations on materials used in previous studies. The purpose of current study was to evaluate the applicability of PU foam as a new option for construction of SEISMIC buffers with regard to its benefits. Hence, the behavior of non-yielding retaining walls was investigated in two conditions of with and without presence of the SEISMIC buffers by conducting of a series of 1g shaking table tests. SEISMIC buffers included PU foam blocks, which were prepared by injecting foam into the cubic molds and spraying a certain amount of water on the specimens. A total of 13 tests were carried out on two models (retaining wall with and without SEISMIC buffer) with changing the input base acceleration from 0. 07g to 0. 46g. The input motion was a horizontal sinusoidal excitation with a constant frequency of 3. 6 Hz, which was applied for 10 seconds to the longitude direction of the model. The model responses including wall force and backfill soil displacement were measured during the excitation in each test. The results showed that the implementing SEISMIC buffers made from PU foam reduce the total and dynamic horizontal wall forces on average of 30% and 45%, respectively. The force attenuation and backfill soil displacement have an inverse relationship to each other. For an equal Normalized compressible inclusion stiffness, this type of foam has a better performance in comparison with similar materials such as expanded polystyrene foam (EPS). Moreover, it is identifying that the force attenuation is not uniform along the height and the maximum attenuation occurs at the top of the retaining wall. The force distribution is triangular for static conditions. As the peak base acceleration is increased and the contribution of dynamic loads on upper elevations is increased, the force distribution becomes nonlinear. Therefore, at earthquakes with moderate to high intensity, the point of application of total horizontal force is transferred to the upper elevations of the retaining wall. Moreover, it is revealed that the efficiency of this technique increases for moderate to high-intensity earthquakes (acceleration amplitude more than 0. 24g).