# مقالههای a Johari

**توجه:**محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.

##### ۱Prediction of Undrained Lateral Load Capacity of Piles in Cohesion Soil Using Genetic Programming

اطلاعات انتشار:
نهمین کنگره بین المللی مهندسی عمران،
سال ۱۳۹۱

تعداد صفحات:
۸

In many engineering project piles shall be designed for lateral loads due to earth pressure, earthquake or wind forces on the structures. This requires estimation of ultimate loads based on which safe working loads will be assessed. In this research, a genetic programming (GP) approach is employed to predict the lateral load capacity of piles in cohesion soils. The GP model requires an input terminal set that consists of diameter of pile, embedment length of pile, eccentricity of load and undrained shear strength of soil. The output terminal set consists of the lateral load capacity of pile. For developing the genetic model GP software (GPLAB) providedby MATLAB was employed for the analysis. Furthermore, GP simulations were compared with the experimental results as well as the models proposed by other investigators. The comparison of the results indicates that the proposed approach was accurate and robust in representing the lateral load capacity of piles in cohesion soils.<\div>

##### ۲Reliability Assessment of Shear and Longitudinal Wave Velocity Using Point Estimated Method

اطلاعات انتشار:
نهمین کنگره بین المللی مهندسی عمران،
سال ۱۳۹۱

تعداد صفحات:
۸

During the earthquake, seismic waves are propagating vibrations that carry energy from the source of the shaking outward. Seismic waves can be distinguished by the velocity and shapes of propagation. The velocity's waves depend on the elastic properties and density of a soil layers that waves pass through them. However, the inherent uncertainties of the soil layers properties dictate that problem is of a probabilistic nature rather than being deterministic. Probabilistic analysis of earthquake waves has beenused as an effective tool to evaluate uncertainty so prevalent in variables. In this research the pointestimated method is used for probabilistic analysis and reliability assessment of shear and longitudinal wave velocity. The stochastic selected parameters are density, elastic modules and Poisson's ratio which are modeled using a truncated normal probability distribution functions. The results are compared with the Monte Carlo method. Comparison of the results indicates superior performance of the proposed approach for assessment of reliability<\div>

##### ۳One Dimensional Stochastic Analysis of Site Amplification Potential Using Jointly Distributed Random Variables Method

اطلاعات انتشار:
هفتمین کنگره ملی مهندسی عمران،
سال ۱۳۹۲

تعداد صفحات:
۸

The amplitudes of seismic wave might amplify significantly as it propagates through the soil layers near the ground surface during an earthquake. Analysis of site amplification potential is strongly influenced by the uncertainty associated to the definition of soil thickness and their properties. In this paper, the jointlydistributed random variables method for stochastic analysis of site amplification is used. The selected stochastic parameters are shear wave velocity and the soil thickness. The circular frequency is regarded as a constant parameter. The base is considered as a rigid rock and no damping is assumed for soil layer. Theresults are compared with those of Monte Carlo simulation. Comparison of the results indicates good performance of the proposed approach for stochastic analysis of site amplification potential. Sensitivity and parametric analyses are conducted to verify the results<\div>

##### ۴Reliability analysis of embankments using stochastic finite element method

اطلاعات انتشار:
هفتمین کنگره ملی مهندسی عمران،
سال ۱۳۹۲

تعداد صفحات:
۷

Embankments are impounding structures made from compacted soil. Several methods can be used for determining mechanical behavior of these structures. Among them, the deterministic Finite Element Method (FEM) is a powerful method for this purpose. The main drawback in the application of this technique generally arises from the large uncertainties affecting the mechanical properties of materials in the model. Hence, finite element method in conjunction with stochastic analysis methods should then be used to assess the results of the analyses in probabilistic terms. In this paper, the usefulness of this approach for engineering purposes is investigated by analyses of embankments constructed by compacted soil. Finite element analyses are performed together with Monte Carlo simulations (MCs) and Point Estimate Method (PEM) and the results are compared. The results show that this technique can be useful to evaluate the relative influence of each designing parameters. Uncertainties affecting vertical displacements which may influence a large earth dam are also presented.<\div>

##### ۵Stochastic Analysis of Dynamic Soil Liquefaction

اطلاعات انتشار:
هفتمین کنگره ملی مهندسی عمران،
سال ۱۳۹۲

تعداد صفحات:
۷

Liquefaction of soils, defined as significant reduction in shear strength and stiffness due to increase in pore pressure. This phenomenon mostly occurs during the earthquake and it can be assessed in pseudo–static or dynamic loading types. However, in each type, the inherent variability of the soil parameters dictates that the problem is of a probabilistic nature rather than being deterministic. In this research, a stochastic analysis is used for reliability assessment of liquefaction potential based on dynamic loading. The Monte Carlo simulations were used for that purpose .The selected stochastic parameters are soil parameters such as shear modulus, Poisson ratio, unit weight, and friction angle. The thickness of soil layers, the initial water table position and time history record are regarded as constant parameters. This analysis shows that, for the considered case, the Poisson ratio and unit weight are the most subtle Parameters in order to define the liquefaction probability.<\div>

##### ۶Analytical Reliability Assessment of Damped Soil on Rigid Rock Response

اطلاعات انتشار:
هفتمین کنگره ملی مهندسی عمران،
سال ۱۳۹۲

تعداد صفحات:
۸

One of the most important problems in geotechnical earthquake engineering is the evaluation of ground response. Analysis of ground response is highly amenable to probabilistic treatment because ofuncertainty associated to the soil properties. In this research, the jointly distributed random variablesmethod is used as an analytical method for reliability assessment of a uniform damped soil on rigid rock response. The selected stochastic parameters are damping, shear wave velocity and thickness of soil layer. The angular frequency is regarded as a constant parameter. The base is considered as a rigid rockand. The results are compared with those of Monte Carlo simulation. Comparison of the results indicates good performance of the proposed method for reliability assessment of ground response. Sensitivity analyses are conducted to verify the results<\div>

##### ۷An analytical reliability assessment of cohesivevertical cutstability

اطلاعات انتشار:
اولین کنفرانس ملی مهندسی ژئوتکنیک،
سال ۱۳۹۲

تعداد صفحات:
۷

Slope stability analysis is a branch of geotechnical engineering that is highly amenable toprobabilistictreatment. Probabilistic analysis of slope stability has received considerable attention in theliterature, andhas been used as an effective tool to evaluate uncertainty that is so prevalent in variables. In this research,the jointly distributed random variables method is used for probabilistic analysis andreliability assessmentof the stability of cohesive vertical cut. The selected stochastic parametersare height, cohesion and unitweight, which are modeled using a truncated normalprobability distribution function. The angle ofsloperelative to vertical is regarded as constant parameter. The results are compared with the MonteCarlo. Comparison of the results indicates thesuperior performance of the proposed approach forassessment of reliability<\div>

##### ۸Evaluation of static liquefaction of loose sand using an elasto–plastic effective stress model

اطلاعات انتشار:
اولین کنفرانس ملی مهندسی ژئوتکنیک،
سال ۱۳۹۲

تعداد صفحات:
۹

The prediction of liquefaction and resulting displacements is a major concern for earth structures locatedin regions of moderate to high seismicity. Several efforts have been published in literature especiallyduring recent years for developing model to predict this phenomenon. In this paper an elasto–plasticconstitutive model is used that simulates the static liquefaction response of loose sands under monotonicloading in a relatively uncomplicated manner. The model is based on the characteristic behavior of thesoil skeleton. It has several key futures, including a hyperbolic relationship between stress ratio andplastic shear strain and a flow rule for estimating plastic volumetric strain from plastic shear strain.When the soil is nonlinear elastic and\or elasto–plastic, the equivalent constitutive matrix is no longerconstant, but varies with stress and\or strain. It therefore changes during a finite element analysis.Consequently, a solution strategy is required that can account for this changing material behavior. Themodified Newton–Raphson method is used to consider the effect of changing material behavior in thisresearch. The result indicated that the model and developed procedure can predict the pattern ofliquefaction correctly. Based on the result, liquefaction propagates downward in effect on surfaceloading.<\div>

##### ۹Modeling Uncertainties in Soil Properties by Random Finite Element Method

اطلاعات انتشار:
اولین کنفرانس ملی مهندسی ژئوتکنیک،
سال ۱۳۹۲

تعداد صفحات:
۸

The Finite Element Method offers great potential for implementing uncertainties in properties of materials such as soil. In many cases, soil parameters should be considered as random variables or random fields. This paper discusses the Random Finite Element Method in predicting the variation of the elastic settlement due to the uncertainties of the elastic modulus. The geometry and the Poisson’s ratio are considered as invariable parameters. The correlation length for the 30×60 m field is considered 30 m in order to have a conservative estimation of the elastic modulus variation. The number of 400000 realizations of the random field are generated. By generating and analyzing multiple realizations, the statistics and the density function of the maximum settlement is estimated. The reliability of the foundation according to limit state failure, in the form of excessive settlements is estimated.<\div>

##### ۱۰One–dimensional site response reliability assessment of damped soil: A comparative study

اطلاعات انتشار:
اولین کنفرانس ملی مهندسی ژئوتکنیک،
سال ۱۳۹۲

تعداد صفحات:
۸

Ground motion time histories can be significantly affected by the local subsurface geology andmorphology. To evaluate the reliability of the results, the estimation of uncertainties is essential. Theuncertainties come from the input site parameters as well as from the numerical model. In this research,site parameters uncertainty is considered. For this purpose, a computer program was coded byMATLAB and the point estimate method is used for assessing reliability site response. The results arecompared with the Monte Carlo simulation. Damped soil on rigid rock and elastic rock are selected astwo different conditions for comparison. The selected stochastic parameters are damping, shear wavevelocity, density and thickness of the soil layer for elastic bedrock condition. As well as damping, shearwave velocity and density of rock for rigid bed. The circular frequency is regarded as a constantparameter in each step of ground response analysis in the frequency domain. Comparison of the resultsindicates the soil layer on rigid rock has higher magnification on the input motion against the soil layeron elastic rock<\div>

##### ۱۱Reliability Analysis of Static Soil Liquefaction Using Random Finite Element Method

اطلاعات انتشار:
اولین کنفرانس ملی مهندسی ژئوتکنیک،
سال ۱۳۹۲

تعداد صفحات:
۸

Liquefaction of soils, defined as significant reduction in shear strength and stiffness due to increase inpore pressure. This phenomenon can be assessed in static or dynamic loading types. However, in eachtype, the inherent variability of the soil parameters dictates that this problem is of a probabilistic naturerather than being deterministic. In this research, a random finite element analysis is used for reliabilityassessment of static liquefaction potential of loose sand under monotonic loading. The Monte Carlosimulation was used for that purpose. The selected stochastic parameters are soil parameters such as unitweight, peak friction angle and initial plastic shear modulus. An elasto–plastic effective stress model isused that simulates the static liquefaction response of loose sands under monotonic loading. The modifiedNewton–Raphson method is used to consider the effect of changing material behavior in this research.Analysis process was performed in MATLAB code.<\div>

##### ۱۲Rock slopes stability reliability assessment based on geometrical properties

اطلاعات انتشار:
اولین کنفرانس ملی مهندسی ژئوتکنیک،
سال ۱۳۹۲

تعداد صفحات:
۸

Probabilistic analysis of rock slope stability has been used as an effective tool to evaluate uncertainty soprevalent in variables and has received considerable attention in the literature.Generally, uncertainties in thegeometrical properties and rock parameters are two main observations in reliability assessment. In thisresearch the geometrical properties are selected as stochastic variables for rock slope stability with planesliding. The Monte Carlo simulation is employedin probabilistic analysis and reliability assessment. Theselected stochastic parameters are angle of failure surface, height of the overall slope and angle of slope face,which are modeled using a truncated normal probability distribution function. The results show the safetyfactor has a distribution near normal.Sensitivity analysis and parametric study illustrate the angle of failuresurface is the most effective parameter in rock slope stability with plane sliding.<\div>

##### ۱۳Reliability analysis of CPT and SPT probabilistic Bayesian models for liquefaction

اطلاعات انتشار:
اولین کنفرانس ملی مهندسی ژئوتکنیک،
سال ۱۳۹۲

تعداد صفحات:
۸

Liquefaction is a phenomenon wherein soil loses large percentage of its shear strength and stiffness,when subjected to earthquake shaking or other rapid loading. Several field tests such as cone penetrationtest and standard penetration test are used to estimate soils liquefaction. There are uncertaintiesassociated with the various seismic demand and soil resistance variables. Recently several models aredeveloped to implement these uncertainties using Bayesian method. In this research two famousprobabilities of liquefaction Bayesian models based on standard penetration test and cone penetrationtest are considered. The safety factors are calculated in all condition for two models utilizing cyclicresistance ratio in the same situation. The results show the Bayesian model based on standardpenetration test is reliable than cone penetration test.<\div>

##### ۱۴Stochastic Finite Element Method for Reliability Analysis of Earth Structures

اطلاعات انتشار:
اولین کنفرانس ملی مهندسی ژئوتکنیک،
سال ۱۳۹۲

تعداد صفحات:
۸

The stochastic finite element method aims at constructing a probabilistic representation of the responseof a mechanical system, whose material properties are random fields. The response quantities, can be thenodal displacements, are represented by a polynomial series expansion in terms of standard normalrandom variables. This expansion is usually post–processed to obtain the second–order statisticalmoments of the response quantities. However, in the literature, the stochastic finite element method hasalso been suggested as a method for reliability analysis. In this study, the stochastic finite element methodis considered in conjunction with the first–order reliabilitymethod for finite element reliabilityanalysis.The results show that this technique can be useful to evaluate the relative influence of eachdesigning parameters. Uncertainties affecting vertical displacements which may influence a foundationsare also presented<\div>

##### ۱۵Soil–Water Characteristic Curve prediction by Gene Expression Programming

اطلاعات انتشار:
هشتمین کنگره ملی مهندسی عمران،
سال ۱۳۹۳

تعداد صفحات:
۸

Soil–water characteristic curve is one of the most important parts of any model that describes unsaturated soil behavior as it explains the variation of soil suction with changes in water content. In this research, gene expression programming is employed as an artificial intelligence method for modelling of this curve. Geneexpression programming can operate on large quantities of data in order to capture nonlinear and complexrelationships between variables of the system. Inputs of the model are the initial void ratio, initialgravimetric water content, logarithm of suction normalized with respect to atmospheric air pressure, clay content, and silt content. The model output is the gravimetric water content corresponding to the assigned input suction. The results illustrate that the advantages of the proposed approach are highlighted<\div>

##### ۱۶An analytical solution to reliability assessment of soil shear strength

اطلاعات انتشار:
هشتمین کنگره ملی مهندسی عمران،
سال ۱۳۹۳

تعداد صفحات:
۸

Soil shear strength is a very important topic in geotechnical problems. Shear strength is dependent on a number of variables and is highly amenable to probabilistic treatment. Probabilistic analysis of shear strength is used as an effective tool to evaluate uncertainty of soil parameters. In this research the jointeddistribution random variable method is used for probabilistic analysis and reliability assessment of Mohr– Coulomb shear strength equation. The selected stochastic parameters are internal friction angle, cohesion, and unit weight of soil as well as the depth of which are modeled using truncated normal probabilitydistribution functions. The resultant probability density functions are compared with the Monte Carlosimulation. Comparison of the results indicates superior performance of the proposed approach for assessment of reliability of the shear strength model for unsaturated soils<\div>

##### ۱۷Evaluation of reliability assessment in slope stability analysis

اطلاعات انتشار:
هشتمین کنگره ملی مهندسی عمران،
سال ۱۳۹۳

تعداد صفحات:
۸

The method of Bishop is one of the most practical approaches in limit equilibrium analysis for slope stability analysis. Three variables such as unit weight, friction angle and cohesion are the soil parameters of this method that must be selected as stochastic variable because of uncertainties of soil. In this research, these parameters are selected stochastic and the effect of them is considered in determining the safety factor in this method. Numerical and analyticalapproaches are used for this purpose and the results are compared to each other. Compassion indicates good performance and close results of the approaches for reliability assessment of slope stability<\div>

##### ۱۸Reliability evaluation of rock wedge slope stability by SCM

اطلاعات انتشار:
همایش ملی مهندسی عمران ، شهرسازی و توسعه پایدار،
سال ۱۳۹۳

تعداد صفحات:
۹

This paper proposed a reliability method for evaluation of rock wedge slope stability considering correlated failure modes. A probabilistic fault tree is employed to model the system aspects of the problem. The system reliability analysis is performed by Sequential Compounding Method (SCM). An example is presented to illustrate the accuracy of the proposed method. The stability of the wedge can be evaluated efficiently using the proposed system reliability approach in a more systematic and quantitative way. The probabilities of failure of the wedge from the proposed method are fairly consistent with those from the Monte Carlo simulation method. The results demonstrate that the probability of failure will be overestimated if the correlations between different failure modes of the wedge are not taken into account.<\div>

##### ۱۹Spectral Stochastic Finite Element and it application in Foundation Settlement Prediction

اطلاعات انتشار:
همایش ملی مهندسی عمران ، شهرسازی و توسعه پایدار،
سال ۱۳۹۳

تعداد صفحات:
۷

The random nature of many features of physical events is widely recognized both in industry and by researchers. A realistic analysis and design of physicalsystems must take into account uncertainties contributed by various sources such as manufacturing variability, insufficient data, unknown physics and aging. In aprobabilistic framework these uncertainties are first modeled as random quantities with assigned probability distributions. The probabilistic nature of the response ofthe uncertain system is then estimated using various available methods such as spectral stochastic finite element methods (SSFEM). SSFEM is a powerful tool in computational stochastic mechanics. In this paper effect of spatial variability of soil Young’s modulus on shallowfoundations settlement by using SSFEM and elastic considering soil behavior is presented.<\div>

##### ۲۰An analytical solution for determination of site dominant period in frequency domain

اطلاعات انتشار:
سومین کنفرانس بین المللی پژوهشهای کاربردی در مهندسی عمران، معماری و مدیریت شهری،
سال ۱۳۹۴

تعداد صفحات:
۸

One of the soil properties which is significantly affects the response of a given site during the occurrence of an earthquake is the dominant period. Estimation of this parameter of soil profiles has been the subject of numerous studies. In this paper, four separated damped and undamped soil profiles that are located on rigid or elastic bedrock, for obtaining the dominant period are considered. For each case, an amplification function based on solution of wave equation in frequencydomain is derived. Furthermore, in two cases the results were compared with frequencydomain analysis by DEEPSOIL. The results indicate that dominant period of undamped uniform soil profile is independent to type of bed–rock which is located on it. Also the dominant period in damped soil profile is different with undamped soil profile<\div>

##### ۲۱Comparison of static and sismic bearing bearing capacity of strip foundation using slip line method

اطلاعات انتشار:
سومین کنفرانس بین المللی پژوهشهای کاربردی در مهندسی عمران، معماری و مدیریت شهری،
سال ۱۳۹۴

تعداد صفحات:
۹

Determination of static and especially seismic bearing capacity of foundation using slip lines method is one the interested method in geotechnics project because of its simplicity. In slip lines method, the stress equilibrium equations on the characteristic lines are solved using the finite difference method. In this research, to determine the static and seismic bearing capacity of foundation two programs were codded in MATLAB. For seismic analysis horizontal and vertical seismic coefficient were inserted in equilibrium equations. Comparison of the results shows that the proposed model can predicts close bearing capacity with respect to the literature. The results of sensitivity analysis show that the horizontal seismic coefficient and internal friction angle are the most effective parameters on bearing capacity of the strip foundation. The results indicate that earthquakes have a negative effect on the bearing capacity, so increase in the horizontal coefficient of the earthquake decrease the bearing capacity of the strip foundation significantly<\div>

نمایش نتایج ۱ تا ۲۱ از میان ۲۱ نتیجه