Sharif Digital Repository

In high seismically active regions, such as Iran, shear walls are one of the preferred seismic force resisting system.The efficiency of reinforced concrete bearing walls for resisting lateral forces and controlling lateral drift in high-rise buildings has long been recognized. But in recent decades shear wall dominant buildings or so called tunnel form buildings have been increasingly constructed as the multi-story reinforced concrete buildings. The purpose of this thesis is to assess the seismic performance of concrete shear walls that provide gravity as well as sesmic resistance for this kind of buildings. The studied walls were assumed to be part of 5- 10- 20- and 40- story residential... 

Concrete structures require reinforcement and retrofitting because of possible mistakes in design or calculation, inconformity between plan and implementation, change in occupancy or applied loads, and decay. Development in technology, production of materials, and new methods play important roles in development of structure construction and reinforcement methods. Emerge of new materials creates great demand in studying, surveying, and determining design characteristic and criteria for these materials. One of these materials is FRP composite which is used in concrete structure reinforcement in different ways. In this laboratory research, the effect of external wrapping by GFRP composite... 

In this thesis we have used the low energy effective action of the string theory to find an asymptotic Anti-de sitter metric with a non-vanishing H field. Then we have used the AdS/CFT correspondence to study the effects of the added Kalb_Ramond field on two calculations in the boundary theory. The first one was the calculation of the drag force exerted on a moving quark in the quark-gluon plasma. In the second calculation we observed the effect of the added field on the confinement-de confinement phase transition  

In recent years using concrete and steel together in buildings and bridges to mix their advantages and compensate disadvantages is very common especially in seismic zones. Using Concrete Filled Steel Tubular (CFST) columns is one of these methods. In these columns, steel tube has longitudinal and lateral reinforcement role for helping concrete core to resist against bending moment, shear and tension. Steel tube also creates confinement in concrete and increase compressive strength and prevents concrete from spalling. Concrete core increases stiffness of column and reduces capability of inward local buckling. Behaviors of CFST columns are influenced by loading, characteristics of materials... 

Recently concrete filled steel tubular columns developed in the construction industry. In these types of columns, concrete and steel have efficient and complementary performance because of proper confinement provided by steel tube for concrete which leads to increase strength and ductility of concrete, also concrete prevents local and inward buckling of steel tube. CFST columns have several advantages over conventional reinforced concrete columns such as elimination of formwork and reinforcement, rapid construction, decrease in the column dimensions and saving extra floor space and also improvement in the load-carrying capacity, ductility and energy absorption ability. Despite the above... 

This thesis presents an extension of an analytical method previously introduced for evaluation of the deformation capacity of RC columns. The method utilizes fiber elements to arrive at nonlinear moment-curvature relationship for each segment. An existing stress-strain model has been modified and used in this study. This model considers the crushing failure of confined concrete, buckling of longitudinal reinforcements in compression, and their fracture in tension. It also accounts for the spiral fracture. This method was employed to determine the force-displacement diagrams for circular RC columns dominated by flexural mode of failure, and was calibrated against a number of relevant... 

concrete-filled steel tube offers many practical advantagescompared withconventional structural systems. The concrete infill provides stiffness and strength in compression and restrains local and global buckling. The inelastic deformation capacity of the CFT system is increased by the confinement of the concrete fill by the thin, ductile steel tube, and this significantly contributes to the seismic performance.
In this research, Formation and development of plastic hinges in CFST frames using pushover analysis was investigated. Different frames with rectangular and circular column and I beam weredesigned and Using nonlinear finite element analysis, interaction between steel and concrete... 

Because of mistakes in the design and calculation, incoherence between construction and design, structural changes, changes in loads and also damages caused by the passage of the time, concrete structures need to be improved and strengthened. Polymeric sheets reinforced by fibers (FRP), according to their appropriate characteristic, are more efficient for strengthening concrete structures. Most studies on confined columns refers to confined RC columns with FRP and less mentioned about prestressed columns. In this study, the behavior of prestressed columns is analyzed by modeling a case of prestressed column in a nonlinear analysis software. Samples of confined concrete columns with CFRP and... 

The purpose of this research is evaluating of how the concrete filled composite tube column performs. Nowadays in the construction industry, a new kind of composite column called concrete filled composite tube (CFCT) columns, have become very common. Concrete and composite tubes posses’ complementary performance. Because on one hand, the composite tube makes proper confinement for concrete, on the other hand the concrete prevents internal and local buckling of the composite tube. One of the major advantages of the concrete filled composite tube columns compare to the reinforced concrete column is that there is no further need for reinforcement and molding, which results in swifter... 

In this thesis, we investigate the effects of topological constraints in catenanes composed of interlinked ring polymers on their size in a good solvent as well as on the location of their θ-point when the solvent quality is worsened. We mainly focus on poly[n]catenanes consisting of n ring polymers each of length m interlocked in a linear fashion. We study the scaling of the poly[n]catenane’s radius of gyration assuming that R ~ m^μ n^ν with µ = 16/25 and ν = 3/5 in a good solvent, with these values of µ and ν obtained by means of a Flory-like theory and further confirmed by numerical simulations. We show that individual rings within catenanes feature a surplus swelling due to the presence... 

This study presents an experimental and numerical investigation on the compressive behavior of a new type of composite column which consists of both solid and hollow concrete-filled UPVC tube with and without GFRP wraps.Composite construction has been often more economical than traditional concrete construction, because this system realizes the most effective use of concrete, and composite members in the structural system.The enormous potential of using plastic tubes in composite systems will be illustrated by this research. It is an economical type of column in construction.This research aims to study the behavior of UPVC-confined columns under axial compression. A sum of 132 specimens are... 

In this study, the experimental study of kerosene mild spray combustion with the presence of the chamber has been investigated. The test rig that has been studied and improved is Sharif University of Technology's MILD Combustion Test Rig on a laboratory scale, which provides the possibility of studying spray combustion with preheating and high dilution. This test rig, while solving the problems of similar test stands, has the possibility of operating with liquid kerosene fuel, which is widely used in various industries. This test rig is axially symmetrical and provides the possibility of providing co-flow air with the desired temperature, swirl number and dilution rate for a liquid fuel...