نشریه آنالیز سازه - زلزله
سال دوم شماره 2 (تابستان 1384)

 In this paper, the behavior of retaining walls and it’s backfill have been investigated harmonic load with the help of finite element method using plaxis software. The wall has been considered to behave elastically and the elastoplastic Mohr-Coulomb model has been used for the soil behavior. Interface elements are placed around the wall to model the interaction between the wall and the soil. Beam elements has also been employed to model the flexural behavior of the wall. Absorbent boundaries are specified at the right and left hand side boundaries in order to avoid the spurious reflections of the compressional and shear waves. The analysis is conducted in the time domain using the Newmark step-by-step method to numerically solve the equation. In this research, the effects of the geometric parameters, wall rigidity, backfill rigidity and soil damping have been investigated. Furthermore, the effects of loading parameters such as amplitude and frequency of the load on the response of the wall have also been studied and the results have been analyzed, assessed and discussed.

When a dam is constructed on a river path, inevitably sedimentation of alluvial materials occurred. Therefore, the initial capacity of the reservoir reduce gradually, and if don’t predict the effects of this phenomena and its proper control methods, the application of the reservoir may be affected. The findings of this thesis confirm that, the sedimentation in reservoirs and the variations of the bed and free surface profile of the reservoirs depend on the adoptive methods used for solving this equations and also on the kind of the experimental equations used for calculating the sediment load and its physical characteristics. Also this study shows that, using the simplified assumptions (Steady state flow) with respect to the physical characteristics of sebiments and the kind of the adoptive equations of bed load is very sensitive.  In this research, study 2-d numerical modeling of sedimentation in researvoirs (case study of shahid kazemi dam of bukan), that a mathematieal moael is presented for studying aggradation an degradation in allnvial channels with width of unit, two-dimensional, steady, gradually varied flow equations and the sediment continuity equation are solved numerically bye the second-order, accurate, explicit finite difference scheme developed by lax. For this purpose, the dam’s data in the sarogh-chi station with three sediment discharge equations (Hassan zadeh-nilsen-mear piter) are used. And finaly some results about the capability of model are obtained.

 Many researchers have been efforted to identify the shape of distribution of stress and strength of castellated beam and base on that, offer a method for design that members. Through this methods, comparing virendil method by simplicity and reasonable results, have been used widly. Regardless from shortcoming of this method, there is two idea for distribution of stresses via primary bending in T- section. In this paper we have tried by modeling of castellated beams which tested in refrence [3] and analyzing them in plastic and elastic condition, the shape of distribution of normal and shear stress studied and finally we conclude that if primary bending stress distribution bee assumed uniform, better result will bee obtain. Also the maximum value of normal stress in flang occure in correspond area with middle length of skew edge of opening.

The collapse of a compression member gives rise to decrease of the load carrying capacity of the member. To perform a nonlinear analysis, in addition to the precritical behavior, the post-critical behavior of the compression member also must be determined. In this study, because of certain advantages of the finite element method, this method has been selected to evaluate the axial load-axial displacement relationships of the compression members. For determining the behavior of a pinended member using finite element method, the following observations have been considered: an elastic-pefectly plastic material behavior is assumed; the intial curvature associated with the bowing of the member has been considered as an initial imperfection; each member has divided into ten element and behavior of each element has been modeled by the Kirchhoff thin beam element; both of the material and geometrical nonlinearity has been considered in the analysis; to trace the equilibrium path through a critical point into the post critical range, the Arc-length method is used. The member type most commonly used in space structures is circular hollow (tubular) section and the present study is limited to the investigation of the post-critical properties of compressive tubular members with various selenderness ratios and also various imperfections.

The Tabriz fault in northwest of Iran is the important geological structure in our country which historical earthquakes were recorded around it. The purpose of this paper is the study of Tabriz fault seismotectonic activity. The method of research is drawing 23 cross section vertical to Tabriz fault between Tabriz and Bostan-Abad distinguish mountain-front faceting, mountain-front sinuosity and the ratio of width of the froth of the valley to depth it. The result shows that Tabriz fault is an active fault.

In fact the most suitable method for finding the load bearing capacity of a member under the axial load or axial load and bending is make use of the interaction diagrams. To analysis and design the hollow circular, square and rectangular high strength concrete (hsc) column shapes, a linear strain variation was assumed in the cross-section height of the members and then the static equilibrium equations are written by considering the properties and relationships governed in (hsc).Based on this, for different variables such as, concrete compressive strength, reinforcement stress, concrete cover, ratio of thickness to the section dimensions and the bars arrangement, a computer program was developed by the Matlab software and the total number of 441 interaction diagramed were drawn for (hsc) columns. The use of such diagrams is a safe and easy tool for analysis and of hollow hsc columns of different shapes.

 Urmia lake consists of such specific encyclopedias as natural, hydrochemical, hydrodynamics, geology and environmental, where they recognize it from the other lakes around the world. Therefore, for the revenue operation of this lake, it is necessary to understand the mentioned specifications appropriately. Regards to the importance of the lake road project, it requires to evaluate those specifications. This paper examines the hydrodynamics encyclopedia of the Urmia lake. It is accountable not only for the transport of sediment and sludge, but also it has extreme effects on the structures and related elements in the lake. Using the C programming language, the simplified Navier-Stokes equations have been solved numerically. On the basis of the results, it can be found that the water circulation includes two circulation cells located at each sides of the constructed freeway, which is responsible for the transportation of a higher volume of sediments. In comparison with the constant water depth at the lake, flow potential functions and velocities due to the dominant winds stress, has been found to have some similar patterns, except in their magnitude, quantity and direction.

According to non-existence of accurate inspection tools on various steps of design and construction of buildings in the past, also due to any change in function of some structures and finally of seismic activities of residential regions of the country, vulnerability assessment of existing structures is necessary. Evaluation of vulnerability of the structures is classified in two categories, quantitative and quantitative methods. In qualitative methods, the vulnerability of the structures is investigated exactly and in details. In this paper a quantitative method based on Japanese structural code is used to evaluate the vulnerability of a few concrete buildings in Urmia city. In this method, two parameters named structural seismic capacity index Is and lateral load capacity index q are introduced for each story. Then, by determining limitation for these two parameters the vulnerability of the buildings can be assessed.