Sharif Digital Repository

In this thesis, the behavior of proposed moment resisting precast beam-column concrete connection under cyclic and monotonic loads is investigated. In this study, the finite element models of precast and monolithic middle and corner connections are created. The results of finite element analysis under cyclic loading is verified with existing experimental results based on failure mode, ductility, energy dissipation capacity and flexural strength. Based on the results of nonlinear finite element analysis, the analytical behavior of samples is in good agreement with experimental results and finite element analysis of proposed precast connection can be replaced with supplementary tests. Then the... 

Using mixed building system of structural steel and reinforced concrete improves the resistance of the structure in comparison with using either material alone. Coupled shear walls is one of these new systems. Coupled shear walls by definition is a series of walls coupled by beams as a central core structure with opening to accommodate doors, elevator wells, windows and corridors. Coupled shear walls can provide an efficient structural system to resist horizontal force due to axial and seismic loads. One type of coupled beams is Steel Coupling Beams (SCB) which consists of steel beams and reinforced concrete shear walls which represents a cost and time-effective type of construction. Some... 

Performance of reinforced concrete frames is highly dependent on detailing of the joint connections between its members, such as beams and columns. To have a good structural behavior, joints must show ductile behavior and designed based on the philosophy of strong column-weak beam. In the case of sever lacking ductility, strength or even rigidity of the connections, or having a weak column-strong beam, in the existing structures, there is a need for seismic upgrading of the connection. There are several ways for seismic upgrading of this type of connections.In this research, using steel plates for seismic upgrading of Concrete Beam-Column connections subjected to axial and cyclic loads has... 

The Concept of causation plays a major role in Hume’s philosophy and as yet has been debated between philosophers. This Thesis aims to Consider the main part of Hume’s view about Causation, but it also Ventutes into more recent approaches in this subject. In first chapter, we attend to Consider The project of Hume named "Seience of man" and The associative mechanism of causation is expressed. In Second chapter, We turn to three famous interpretations of Hume’s view and the meaning of two definitions of Causation is discussed. In third chapter, we try to analyse the real nature of necessary Connection. According to fourth chapter, we again attend to three interpretations and recognize the... 

This thesis is concerned with studying several aspects of the generalized isoperimetric problems on weighted graphs. In this regard, as a generalization of well-known Cheeger constant, we define k-th isoperimetric constant as the minimum of normalized outgoing flow over all k-subpartitions (disjoint subsets) of the vertex set. Also, we investigate basic properties of these parameters and particularly we prove a Federer-Fleming-type theorem. We then introduce a generalized Cheeger conjecture which is a generalization of celebrated Cheeger inequality and relates defined isoperimetric constants to higher eigenvalues of Laplace operator. In order to find a partial proof for this conjecture, we... 

In the present study, design and manufacturing of a connected pipe liquid fuel ramjet test platform is implemented for performance investigation of a research liquid fuel ramjet burner in the thermodynamic flight conditions. Design and manufacturing of platform systems include: the hot air supply system, the liquid fuel system and the square cross-sectional combustion chamber with the v-gutter shape flame holder. In order to determine the performance range of subsystems, calibration process has been carried out. Calibration process of the hot air supply system includes: determining of the burner inlet velocity and temperature. Also, calibration of the liquid fuel system includes: determining... 

In recent years, composite systems comprised of reinforced concrete columns and steel beams, have taken consideration. This system took its own advantages both from steel and concrete systems. Joints of this system categorized into through-beam-type and through-column-type. In this research, after reviewing past studies, two kinds of the joints were modeled in ABAQUS finite element program and seismic performance of these two joints were evaluated. These two selected joints were tested by Chin-Tun Chen and Cheng-Chih Chen ( ) and also Hiroshi Kuramoto and Isao Nishiyama ( ). After verifying the finite element model with the experimental studies, a parametric study were conducted on the steel... 

Swarm Robotics consists of homogonous robots with considerable abilities. In recent years, engineering applications, including multi-agent control and air vehicles have been existed and engineers have been interested more in multi-agent systems. Currently, progressive number of studies is being done on decreasing the expenses, developing applicability and compactness of robots. Exchanging some simple robots with a complicated robot results omitting over-complexity and expensive equipments. This project is looking for a method for emerging connectivity and consequently maintaining it for a swarm robotic suffering from limited communication. Limited communication means that agent distinguish... 

The steel-concrete composite beams are increasingly used in bridge and building construction in recent years. A shear connection between the steel and concrete should be provided to effectively transfer the shear force and to make the two materials act as a single unit. The mechanical shear connectors provide this means. They are the essential component of any composite beam system. Many studies have been performed on shear connectors and many different steel shapes have been suggested for connectors. The steel studs and channels are the most popular code accepted connectors. However, economic considerations continue to motivate the development of new products.
Present knowledge of the... 

Opportunistic spectrum access in cognitive radio networks has introduced multiple challenges in the realization of this technology. One of these key challenges is spectrum mobility, in which a secondary user (SU) must be able to vacate channels upon the appearance of a primary user (PU) and reestablish a communication link to avoid service termination, known as spectrum handoff. For a connection-based modeling, multiple interruptions can occur, which lead to multiple handoffs; hence, in a proactive approach, a sequence of target channels, rather than a single target channel must be determined. The first parts of this thesisis dedicated to the analysis of a time-slotted cognitive radio, in... 

Lateral forces on structures are transferred to braces as tensile and compressive loads. These loads enter the beams and columns through the gusset plates. The gusset connections to the beams and columns must be such that they be able to pass the loads through themselves. So far, five analytical models have been proposed for this connection and only one of them is recommended by AISC. These models estimate the existing forces and moments on the connection. The analytical models are: model 1 (KISS), model 2 (2A-AISC), model 3 (Thornton), model 4 (Ricker) and model 5 (Richard). Among these models, only model 3 is recommended by AISC because the others are more conservative. It should be noted... 

As technology develops, the need of instruments which could be used for improving the rate and accuracy of the manufacturing increases. This makes the robots inevitable to use in most industries. Among the robots, cable-driven robots have special characteristics that increase the tendency of using them.Multi-body cable-driven robots are novel type of cable-driven robots that have advantages compared to single-body ones. Capability of use in rehabilitation applications, in which the different parts of human body have to move separately, is one of the advantages of multi-body cable-driven robots.The first aim of this thesis is to extend the tensionable workspace concept for multi-body... 

Iran requires basic changes in using construction materials and industrial system of house production due to its particular climatic conditions such as being located on the earthquake belt and social conditions such as lack of house. 3D panel is one of the best options for industrial construction and especially mass building.
In this thesis, different suggested designs for L & T shaped wall to wall connections of 3D panel under lateral-cyclic and gravity loading were modeled and analyzed by ANSYS software. Numerical analysis indicates that concrete perpendicular hank and welded wire mesh WWF 3/3/50/50 have positive effect on the ultimate strength and ductility of the connection. Hence,... 

We analyze the fundamental communication limits and capabilities of random wireless networks. In order to achieve this goal, we investigate and analyze efficient communication strategies in such networks. The traffic model considered is unicasting. Also, we consider two different channel models, namely, the geometric channel model and the random connections model.
In networks with random connection model, channel powers between different nodes are drawn from a common distribution in an independent manner. We assume an on-off strategy for operation of transmitters, and show that finding the optimum transmission strategy problem is an NP-hard problem. Thus, we propose a heuristic algorithm... 

Composite Reinforced Concrete-Steel (RCS) frames which have reinforced concrete columns and steel beams attracted a lot of attention in recent years. They take advantage from the benefits of both reinforced concrete and steel frames thorough using the optimum combination of concrete and steel structural elements. In this research six structures including three 3-story, and three 6-story buildings are designed in a region with very high seismicity risk. These structures include composite RCS moment frames, special steel moment frames, and reinforced concrete special moment frames. RCS moment frames which are designed they not only have reinforced concrete columns similar to reinforced... 

Base plates as the connecting components of steel structures to their foundations, have a crucial role in the behavior of these structures. In order to limit the thickness of base plates hence their cost within reasonable values, various types of attachments (stiffeners) are normally added to them. In this project 6 different configurations, Models, for the base plate and its attachments were considered and studied through finite element analysis. Each Model was studied under the combination of biaxial moments and a range of compressive loads including 0, 0.05 P/Py, 0.10 P/Py and 0.15 P/Py, where Py is the plastic load of the column. The moment-rotation curves of all models under various... 

In the present study an air supply system of a connected-pipe ramjet test facility for liquid fuel ramjet engine in theoretical and numerical base designed and optimized that the purpose is for performance test of a ramjet engine combustor in flight condition. The flight condition gained from previous assessment that is 1.5 kg air in 10 bars and 550 K. Air supply subsystems consist of air tanks, compressors, valves, regulators, preheater, and fuel and oxygen systems that are designed in a preliminary process and then valves, orifices, and fuel and oxygen systems optimized by HYSYS program. In the last step preheater that is a gas turbine combustor investigated and possible changes made by... 

Composite systems consisting of concrete columns and steel beams are introduces as structural systems in recent years. These structural systems enjoy merits of both steel and concrete frames by efficiently combining the advantages of them. This study is allocated to lateral force resistance system using armed concrete and structural steel. Advantages of composite structures rather to those of two other conventional ones are among performance characteristics under ultimate loads, economical conservation, and higher speed of construction.In this research the aim is to study these frame under earthquake induced loads. The seismic performances of these composite frames with through column beams,... 

Let G be a graph. A P3-factor of graph G is a subgraph of G such that each component is isomorphic to P3. In 1985 Akiyama and Kano conjectured that every 3-connected 3-regular graph of order divisible by 3 has a P3-factor. In this thesis we conjecture that every 3-connected 4-regular graph of order divisible by 3 has a P3-factor and also show that this conjecture concludes the previous one. Moreover, we investigate connected factors and some 3-vertex induced factors in graphs and show that every r-regular graph of order n (3 j n) has a P3-induced factor, if r _> 8n/ 9-1