Sharif Digital Repository

In this study, the bolted connection of two steel corrugated plates, commonly found in silo walls, was investigated. Following the validation of FEM models, the test design described in AISI S905 for cold-formed steel bolted connections was referenced. The geometry of the corrugated plates was selected in accordance with ASTM A796. The effects of various parameters, including plate thickness, bolt diameter, steel type, bolt placement, wave geometry, and restrained curling, were analyzed with respect to the bearing capacity of the connections. Based on the analysis, the most significant parameters were identified, and 54 additional models were developed to further investigate the interaction... 

Steel connections are constantly exposed to strength degradation due to corrosion. The extent of this reduction varies based on preventive measures and environmental corrosion severity. To more accurately evaluate the performance of bolted steel structures in corrosive conditions, it is necessary to define the behavior of corroded bolted connections and incorporate it into structural analyses. A literature review in this area reveals that most previous studies have focused on the behavior of structural members, with very few addressing the impact of pitting corrosion on connections. Therefore, this research aims to examine the performance of bearing connections under pitting corrosion and to... 

In this research the behavior of Circular Steel Tubes (CSTs) with corrosion under axial force and bending have been studied. There are several factors leading to corrosion in steel structures, especially marine structures that results in strength reduction of whole structure. Steel tubes are widely used in construction of on-shore and off-shore structures such as, oil rigs and platforms, oil and gas transmission lines. Current study focus on strength reduction of steel tubes with “pitting corrosion”. To this end numerical analyses using finite element software, Abaqus, have been performed. Therefore, utilizing verified models, the simultaneous effect of bending, axial load and corrosion on... 

Steel cylindrical silos are one of the most practical structures in handling and storage of bulk solids in many industries and agricultural sectors. Steel silos may be composed of flat or corrugated sheets. Due to small wall thickness, shell structures are vulnerable to buckling failure. Unsymmetrical loading conditions rising from frequent filling and discharge cycles during the lifetime of these storages are almost the main reason for local or global instability of silos. However, they may experience additional lateral loads such as, wind load and seismic load that essentially impose unsymmetrical pressure on shell walls and can lead to buckling, as well. Under wind pressure, steel... 

Cylindrical steel shells are common industrial structures. Due to their thin thickness, these structures are very susceptible to buckling under applied loads. For access and repair purposes, cutouts of various shapes and dimensions are used in these structures. The presence of such cutouts increases the sensitivity of these structures to buckling; therefore, it is necessary to use stiffeners with different dimensions and shapes around the opening to restore the lost capacity. Cylindrical shells are designed in different lengths for use in different structures. The most common shapes of these structures are silos, tanks, and turbines. Due to the effect of the slenderness of these structures... 

In this study a new metallic damper, namely Corrugated steel plate Honeycomb Damper (CHD) is presented. The CHD proposed ease of manufacturing and implementation in various structures with a stable energy dissipation characteristic when subjected to lateral loading. The basic configuration of the CHD consists of two steel plates that are bent to form trapezoidal corrugations. The plates are then welded together along the bent lines to build the honeycomb geometry. In order to investigate the behavior of the CHD, first a closed-form expression for the elastic stiffness and yield strength was obtained by the matrix analysis method. Then, to study the non-linear behavior of the CHD, three... 

The principal objective of this investigation is to furnish a straightforward and effective technique for computing the load-bearing capacity of fillet welds when subjected to in-plane eccentric loads. Some approaches have been put forth to ascertain the load-carrying capability of fillet welds under such conditions over time. The existing design methods, such as the conventional elastic method, are very conservative and do not match the test results well due to neglecting the weld group's ductility and strain compatibility. On the other hand, the instantaneous center of rotation method (IC) considers the above parameters but requires complex calculations. Therefore, in the present study, a... 

One of the important questions in mathematics is generalized. In case of metric spaces, one of the questions is: Can we extend notions of Riemannian geometry to arbitrary metric spaces smoothly? Ricci curvature is one of the most important concepts in differential geometry. Ricci curvature is defined for the Riemannian manifold and has many applications in mathematics and physics like Einstein’s equation in relativity theory. There is a good notion for a metric space having “sectional curvature bounded below by K” or “sectional curvature bounded above by K”, due to Alexandrov. Can we define the concept of Ricci curvature in metric space? A motivation for this question comes from Gromov’s... 

Seismic design codes reduce loads by using response modification factor. Because of the reserved strength in structural elements and capacity of structure to dissipate energy, structures can be designed for lower seismic loads. This factor has modified over time. In this thesis, the effect of the reduction in behavior factor on the response of two kinds of reinforced concrete systems were evaluated. Moment resisting frames and dual systems with different heights and regularity in plan, heve been design according to the behavior factor which is recommended in the 3rd edition of the Iranian codes of practice for seismic resistance design of buildings (Standard No. 2800). Drift and... 

Generally, nowadays, machine learning methods are used in many different areas for their superiority over other methods of prediction. Although being a tough task, stock market prediction with machine learning approaches is being spread due to satisfying results published ever yday. Machine learning methods usually use varied kinds of data ,including structured data such as market data, technical indicators and some fundamental data as well as unstructured one entailing text and graph data in order to enhance their predictability capacity. In this thesis we aimed to find out more about the importance and the contribution of structured data in prediction and we tried to attain a framework... 

This thesis presents an inventory control system which is based on Meta-heuristic Algorithms.In this thesis we will optimize the input values of our tree-echelon inventory model (keeping costs,stock worth,reorder costs,...) with these Algorithms. The presented method is able to determine the optimal stock level, costs of system and number of shipments in the system. The method is basically a decision support system (DES) and it is able to provide the order scheduling parameters of goods at operational level. The aim of the current research is to demonstrate that a Meta-heuristic algorithmis capable of solving complex inventory problems and with future improvements it is able to achieve... 

Poincare conjecture is one of the rst eorts for classifying 3-manifolds that was stated in the begining of 20th century. Eorts for proving this conjecture continued for about 100 years and nally Perelman has solved it in 2003. He has used Ricci ow which has been invented by Richard Hamilton in the early 80's. In this thesis rst we will introduce Ricci ow and will state the results before Perelman such as short time and long time existence of solution. Then we will mention some applications of Ricci ow and will state an explanation of the proof of uniformization and Calabi conjecture by Ricci ow. After that we start the main part of the thesis. In this part we will montion one of the... 

Nowadays best using of fossil fuels sources of the country (and) importance of comparison against lack of capacity in petrol production make determined the programmers and the directors to foresee and design expanded programs of the goals, to use natural gas for car fuels. To reach fulfillment of these programs, the confirmed needs of the natural gas cylinders are improved and make it essential to invest on producing compressive natural gas cylinders. In this way economical and technical change researches has been done in order to construct on department to produce 200,000 compressive natural gas cylinders in a year during two sets.(shifts) According to the results of technical researches... 

Different molybdenum oxide nano/micro structure thin films were synthesized by thermal evaporation method under various growth conditions such as deposition time, temperature and evaporation source-substrate distance. Molybdenum oxide nanostructures grown on Si(100) such as nanowalls, nanostars and nanowires were characterized with scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). Shape and type of nanostructures were determined with SEM, AFM and HRTEM analysis. XPS analysis showed that the synthesized nanostructures contained Mo6+, Mo5+, Mo4+ and... 

One of the most important parts of a cement factory is the cement rotary kiln which plays a key role in quality and quantity of produced cement. In this part, the physical exertion and bilateral movement of air and materials, together with chemical reactions take place. Thus, this system has immensely complex and nonlinear dynamic equations. These equations have not worked out yet. Only in exceptional case; however, a large number of the involved parameters were crossed out and an approximation model was presented instead. This issue caused many problems for designing a cement rotary kiln controller. In this thesis, we employed a nonlinear system identification method for identification,... 

Optomechanical systems have attracted considerable attention in the last decade. Such a raising prominence is mainly due to its capability in providing new insight into the quantum behavior of macroscopic objects and exploring the interface between quantum and classical mechanics. Alongside this fundamental quest, cavity optomechanics has many other benefits, ranging from very precise measurements on forces and positions to quantum information processing. In this thesis, we investigate quantum properties of such systems. Particularly, we study cooling of the mechanical resonator toward its ground state and the entanglement between this mechanical resonator and the cavity field. Cooling the...