Sharif Digital Repository

Lateral spreading due to liquefaction and resulting destruction of buildings is important in Iran because of high seismicity and important infrastructure near south and north coasts of Iran. Lateral spreading is vast lateral movement of sloping ground or level ground ending in an opening like river which is caused by earthquake inducedliquefaction. For considering the effects of lateral spreading during design of deep foundations of structures in a susceptible area, one needs to determine the lateral loads on piles under lateral spreading. Present study investigates the behavior of a 3x3 pile group against lateral loads due to lateral spreading with numerical methods using OpenSees software.... 

Today, application of aluminium alloys in industries is developing. And this is because of some specification of these alloys like high proportion of the Strength per weight. One of the most useful alloys of this alloy group is A356 alloy that contain 7 % Silicon and 0.4 Percent of magnesium, this alloy because of cast ability, heat treat ability specification is use developing in air and automotive industries. But usage of this alloys combined with some difficulties like low fluidity and formation of shrinkage and gas porosities in this alloys. In present work with programmer software Visual Fortran, based on Finite difference method, a simulation model has been developed, can solve heat... 

Using short rammed aggregate piers (RAP) is one of the ground improvement methods that is suitable for loose sands and soft clays. In this method, gravel or crushed stone is placed in layers with specific thickness in a pre-drilled cavity and each layer is fully compacted with impacts of a hammer. The basic advantages of these piers are increasing soil lateral stresses due to aggregate ramming and increasing the consolidation rate due to high permeability of aggregates. The main application of RAPs is soil improvement underneath shallow foundations, in order to increase the bearing capacity and reduce settlement of foundation. Regarding the usual height of 1.5 to 5m of these piers, a... 

Here, we have simulated isothermal vacuum assisted resin transfer moulding (VARTM) using a control volume/finite element scheme. Two dimensional and dimensional (shell geometries) spatial discretization is used. Resin motion through fibers is enforced by vacuum negative pressure in downstream. The governing equations are mass conservation and well known Darcy equation. Using an unstructured triangular grid, complex geometries could be modelled. Application of a quasi-steady algorithm results in a system of linear equation for pressure distribution. This system must be solved in each time step. The point successive over-relaxation (PSOR) scheme is used to solve the system of linear... 

Thermopneumatic micropump is one type of positive displacement micropumps, which has many applications due to its relatively large stroke volume, low working voltage, and simple fabrication in microscale. In this paper, a numerical study of heat transfer and fluid flow in a valveless thermopneumatically driven micropump is presented. For rectifying the bidirectional flow, a nozzle and a diffuser are used as the inlet and outlet of the chamber. Since the fluid flow is induced by the motion of a diaphragm, the numerical simulation includes fluid structure interaction, which requires applying a dynamic mesh. The domain of solution is divided into two sections; the actuator unit, which contains... 

A global rotating atmosphere with polar vortex and super rotation is simulated using a simplified Venus General Circulation Model (GCM). The polar vortex is maintained strongly by meridional circulation develops in the form of a simple Hadley cell, extending from the equator to the pole in both hemispheres and rotation terrestrial planet. Venus Total Polar Vortex Parameter (PVP) was defined like globally integrated super-rotation but at polar skullcaps (60-90 deg). Venus Polar Vortex Parameter is PVP=1.5 that’s qualitatively similar to observed polar vortex. Then with study in terrestrial planet and Titan modeling, we appointed the Polar Vortex Parameter and critical limit of Polar Vortex... 

Nowadays, pile usage in construction of deep foundations has increased significantly, instead of shallow foundation in areas that shallow foundations doesn’t provide enough bearing capacity and measuring the velocity and acceleration due to pile driving is very important. Because, all responses of building and individuals located near the pile driving site influenced by these three parameters: pile vertical displacement, peak particle acceleration (PPA) and peak particle velocity (PPV). One can estimates these important parameters by numerical analysis of pile driving process in different distances and depths to determining the effect of pile driving. Compared values obtained from numerical... 

Out of several ground improvement techniques available, stone columns have been widely used. This technique has been successfully applied to increase the bearing capacity and to reduce the settlement for foundation of structures like liquid storage tanks, earthen embankments, raft foundations, etc., where a relatively large settlement is permissible. This technique has, generally, been proven successful in increasing the stiffness of weak soils, upgrading their safe bearing capacity, and reducing their total and differential settlements, as well as speeding up their consolidation process. The beneficial effects of stone column installation in weak deposits is manifested in the form of... 

The main purpose of designing machine foundation is to limit its motion to such an amount that not to prevent the perfect workability of machine, not to let the foundation strains exceed the elastic limit and also not to disturb the persons working around the machine. The key note in successfull design of machine foundation, is to precisely analyse the response of foundation to dynamic loads induced by machine operations.The numerical study of shallow foundations response to vertical harmonic loads induced by machinaries have been discussed in this investigation.To aim this purpose, FLACD3D has been utilized in order to 3 dimensionally analyse a continuum medium comprising soil-foundation or... 

The commercially available finite element software, FLAC, was used to provide better understanding of the static and dynamic behavior of tieback and anchored walls. Many of the codes dealing with the design of these structures use empirical methods to estimate the amount of deformation under static conditions. Therefore, in terms of static behavior, this thesis mainly focuses on the deformation patterns of the wall and the retained soil. Mohr-Coulomb elasto-plastic constitutive model was used; however, in elastic part the nonlinear Duncan-Change was implemented. The efforts made for better representation of soil behavior resulted in the suggestion of a modification to Duncan-Chang’s... 

Cold-formed steel sections are lightweight materials and suitable for building construction owing to their high structural performance. Conventionally, they are used as purlins and side rails in the building envelopes of industrial buildings. The most common sections are lipped C and Z sections, and the thickness typically ranges from 1.2 to 3.2 mm, and sections with yield strengths at 280, 350 and 450 MPa are commonly available. For connection design, codes of practice for design of cold-formed steel structures only provide design rules for the load carrying capacities of individual fastenings with bolts, screws and welds while no guidance on the structural behavior of connectors such as... 

Cleanrooms have a broad scope of applications from electronics, pharmacy, biotechnology to hospital industries, and are susceptible to fine and ultra-fine particles. In this work operating room in the category of hospital applications is chosen. Airborne particles in the operating room depends on many factors such as room geometry, inlet and outlet design, air displacement rate, obstacles, etc. Surgical light is one of the most critical obstacles in the operating room as it is upstream to the surgery zone. The study presented in this thesis aimed to numerically investigate the influence of radiation emitted from the medical lamps on the indoor airflow quality in operating room environment.... 

Subfloor heating and cooling systems in residential and commercial buildings present advantages from the point of view of comfort conditions and energy saving. In the present work a two dimensional and a three dimensional model for subfloor heating and a two dimensional model for subfloor cooling, using the Fluent software based on the finite volume method were developed. From the point of view of exergy destruction as we may have lower temperature difference between the heating medium and space, we come up with less exergy destruction. To determinate the optimum working conditions of these systems, a numerical model for subfloor heating and cooling is presented. Different methods of... 

Aquatic canopy zones play an important role in maintenance of ecosystems. These areas are ubiquitous near rivers, lakes, lagoons, estuaries and shore lines. Governing dynamical systems through these areas have direct influence on, how nutrients and other vital materials for living things disperse. Also, they can control the amount of dissolved oxygen within the body of water in these regions. Nowadays, investigating the effects of vegetation grabbed the attention of many scientists and is a very important burgeoning field. In this study, the effects of surface cooling which resulting from mild wind blow have been investigated. In fact, two type of different currents form when wind blows... 

Sand production in petroleum industry is a phenomenon of solid particles being produced together with reservoir fluid. This phenomenon is costing industry billions of dollars every year. Corrosion of the pipelines and other instruments, sand-oil separation cost, possible wellbore choke and repeated shut-in and clean-up of the wellbore are some of examples of the costs. On the other hand, a controlled sanding or even sand production invocation has proved to be very effective in increasing production rate, especially in heavy oil recovery, asphalt wells and low PI wells. Discovering the best sand controlling procedure in oil extracting wells, parameters that have the most important effects on... 

According to global improving consumption of distillate products, like gasoline and diesel, reduction in light petroleum production and growth in exploring and extraction of heavy and sour petroleum, changing in refining structure of worldwide oil refineries is necessary and it is crucial to apply special processes for refining, conversion and cleaning of these heavy and extra-heavy petroleum. Gasification of these fuels, i.e. partial thermal oxidation of feed in the presence of gasifying agent (air, oxygen, steam or mixture of them) in the gasifier, is one of the new ways to convert heavy fuel oil to synthetic gas (syngas), that this gas can be used widely in downstream processes. Here,... 

Lateral spreading is a common mode of earthquake-induced failure that usually occurs as a result of liquefaction in gently sloped sandy layers. Numerical simulation of this phenomenon requires fully coupled analysis of displacement of solid sand particles and pore water pressure under seismic loading. Predicting occurrence of initial liquefaction and sub-sequent ground movement requires employing an efficient and robust constitutive model that can predict the undrained behavior of saturated sand under different conditions. In this study, a fully coupled finite element code “PISA” utilizing a critical state two-surface plasticity constitutive model, proposed by Manzari and Dafalias (1997),... 

The use of public transportation in metropolises has developed due to the increase in the population and the need for within-city transportation. Among public transportation service, the use of city subways has attracted more public interest due to its speed, safety, and matching with the environment. Also, one solution for reducing the between-city transit distances,decreasing the accidents and above all, saving the time of the travel is building tunnels and underground lines. Design and construction of underground structures (tunnels),in comparison with surfacestructures, has more complex conditions and considerations that require special studies. One challenging problem fortunnel... 

Petroleum is the main source of energy in the world. So, exploration and production of this strategic matter from earth and sea has a major importance. A large amount of this black gold is hidden under deep seas floors and extraction of these sources requires knowledge of design and technology of construction of deep water offshore platforms and equipments. Convetional Tension Leg Platform (CTLP), configured as 4 cloumns and 4 pontoons, is one of deep offshore platforms moored by several pretensioned tethers. The dynamic behavior characteristics of CTLPs are extracted in this thesis by numerical modeling of CTLP and regular wave interaction. A computer program PARADISE is developed in... 

Monitoring is of particular importance after impounding and during dam operation. In all large dams, by installation of the required instruments the pore pressure, soil mass pressure and displacement during construction, first impounding and operation are measured, then the performance of dam will be analyzed and evaluated. The aim of this study is to evaluate the performance of the "Gavoshan" dam, which has an important role on agriculture development and drinking water supply at west part of Country. To reach this, the values resulting from instruments have been implemented by FLAC software, using "Back Analysis" method. However, this assessment is complete when "back analysis" method is...