Sharif Digital Repository

The flexibility of beam to column connections and its effect on behavior of steel structures is one of the most important problems, which is interesting to engineers and scientists for more than 80 years. Hence many studies conducted on this topic to clarify the behavior of this type of connection. In this work, it is tried to study the behavior of double plate connections, which are welded to the beam web by finite element modeling and mathematical method. A novelty of this thesis is some top trough plate which has been implemented to column under beam flange. Based on finding of this thesis few recommendation can be made related to usage of top trough plate. In brief reduction of... 

Nowadays, Braced Frames systems are prevalent as a structural resisting lateral loads. One of the most crucial prominent of them is Disposable Knee Bracing (DKB). In such a system, braces provide stiffness, while the link elements play an important role as an energy-absorbing fuse to dissipate energy by plastic deformation. In this research, bracing frames consist of shear and/or flexural link elements. The experimental results reveal that hysteresis behavior of link elements remains constant till specific rotation. After that, sharply decrease due to crack failure of these elements occurs. This specific rotation has been reported between 0.06 to 0.08 Rad. Seismic performance factors such as... 

Incremental Dynamic Analysis (IDA) is a parametric analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic loads. Using IDA , the objective is to study the effect of the irregular distribution of stiffness and strength along the height of a 9 story 3D steel structure model. The reference and each modified structure are hence forced to show the complete spectrum of behavior from elasticity to final global instability, allowing the estimation of capacities for the full range of limit-states and enabling a straightforward comparison without needing to “tune” the structures to the same fundamental period and/or the... 

A particular kind of concentric bracing system composed of three members arranged in y-shaped geometry is examined in this thesis. The non-straight diagonal strut of this off-centre bracing causes eccentricity to the system and is connected to the frame corner through a third member. Providing adequate openings in braced bays accompanied by improved energy dissipation are resulted in positive attitude toward using y-bracing frame as a lateral load resisting system. However, lacking of specific design codes could be problematic for engineers. To overcome this incompetency, seismic performance factors including the response modification coefficient, the system overstrength factor, and... 

Concerning the variety of existing buildings and the diversity in the factors which affect the behaviors of structures, subjected to earthquakes, presenting a definite method for studying their seismic vulnerabilities has not been realized yet. Selecting a method which covers all mentioned necessities is extremely wide and complex. From one side, the capacity of structural system should be determined based on its strength and deformability. On the other hand, the nonlinear behavior of structure should be predicted by selecting the probable effects of earthquake on the region. Then, the force or acceleration which causes damage of structure's components, and the whole structural system,... 

Double web angle connection is one of the most simple connections in fabrication in simple frame structural systems. In common design procedures for this type of structural system, it is assumed that double web angle connection behaves as a simple connection, but in this system when bracing used, gusset plates of bracing are connected to top and bottom of double web angle connection, or just in top or bottom, and these gusset plates restraint beam to rotate at the places where it is connected to column. Restraning rotation of beam against column in beam to column connection, may change the classification of connection from simple connection to semi-rigid or even rigid connection. In this... 

In this thesis project the effect of joint rigidity on the behavior of steel braced frames has been investigated. In order to carry out this study on the efficiency of semi-rigid connections, a series of 3-bay braced frames ranging from 6- to 20-story with extended end-plate and flush end-plate connections have been selected and designed. This study has been extended by evaluating the role of the mentioned connections on seismic performance of selected semi-rigid frames under seven famous earthquake records. Having taken a particular performance level, in this case, “life safety” the target displacement and also the lateral load pattern for each frame have been calculated. Then using a... 

Seismic loads are still a challenge for structures and engineers invent and provide seismic resisting systems to resist better against it. Concrete shear walls are well-known seismic resisting system that has had an acceptable performance in occurred seismic events. This system costs noticeable amount of time and material. Fiber-reinforced concretes can be useful to reduce negative effects and provides more positive effects like tensile strength, ductility, impact resisting and etc. Also changes in wall appearance such as corrugating helps to improve shear wall performance as it improves other kinds of plates and shell shaped members in structures. In this thesis, the focus is on “corrugated... 

In the present study, a number of Steel Plate Shear wall (SPSW) models with various infill plates such as perforated and slit infill panels are analyzed and the results are utilized to discuss about behavior of Steel Plate Shear walls with various infill plates. The ABAQUS finite element package is utilized for all Eigen value and incremental nonlinear pushover analyses. Cyclic loading is in compliance with the ATC 24 loading protocol (ATC 1992). To validate modeling, boundary conditions and loading procedures, the experimental results provided by Darren Vian et al. [102, 103] and In-Rak et al. [48, 49] was modeled and analyzed. Investigation of steel plate shear walls made of different... 

The behavior of a beam under moving mass has been always interested in the dynamic of structures. In this study, the dynamic response of beam and plate with general boundary conditions under moving mass were investigated using the Dynamic Green Function. Since the majority of previous studies did not consider the Coriolis acceleration, therefore, this acceleration was used in the present study. Boundary conditions are modeled by the rotational and translational restraint. By moving close to the spring constants of the rotational and translational restraint to extreme values (zero and/or infinity), the boundary conditions can be attained for the desired combinations of end boundary conditions... 

As steel shear walls are usually applied in the central cores of buildings (around the elevators and stairs), the use of opening as door is inevitable in steel shear wall spans. On the other hand, because of weakening the performance of steel shear walls due to the presence of these openings, it is necessary to apply stiffeners around it. The use of stiffeners around all sides of opening continued to beams and columns, is very expensive. Therefore, the necessity of studying on the effect of different arrangements of stiffeners on the behavior of steel shear walls is felt. In this research, a number of steel shear walls with different characteristics in terms of plate aspect ratio, location... 

Base plate is one of the crucial elements in steel structures which transfer force from column to foundation and also prevent stress concentration in jointing area between them. For investigating the behavior of base plate under different caseloads such as axial, transverse and earthquake loads, it is necessary to consider all the involved elements including column, base plate, foundation, anchor rods and also interaction between these elements. In this study the connection between column and base plate, base plate and foundation are analyzed thoroughly. The behavior of base plate with a box type column with and without stiffener under the static loads is analyzed using finite element... 

Column-base connections are one of the most important elements in steel structures which connect the steel frame to the foundation. Therefore, in structures erected in seismic areas, these connections are critical to convey cyclic inertia forces to the frame. In this research the author performed a parametric study utilizing Finite Elements Method (FEM) to investigate the connection’s cyclic behavior. Primarily, the modeling method is verified and calibrated by the use of available experimental data. Afterwards, the parametric computer models are made. Though some researchers have investigated similar connection types, some components’ parameters like the column’s dimensions have not been... 

Steel plate shear walls are lateral load resisting systems, especially against earthquake excitation. They are constructed with or without stiffeners. Stiffened walls are more ductile than without stiffeners walls. In this research, nine thin steel plate shear walls models were considered in three groups of 5story, 01story and 05 story walls. In each group different yield point steel for the infill plate was used. The results showed that, using low yield point(LYP) steel will increase energy dissipation of models up to %36. LYP also improve shear capacity of models up to %96. The results showed that using LYP will cause lower lateral displacement in models  

The Reliability of substation structures with consideration of earthquake uncertainties is one of the most important subjects in structural analysis in recent years. In this project we first introduce IEEE-693-2005, which is the most effective and comprehensive seismic design code for electronic substations. Also in second chapter the rudimentary aspects of Reliability Theory and methods for evaluating the reliability of substation structures is introduced. Then with modeling the most common and most important electronic substation devices in Iran, with consideration of all seismic parameters and their uncertainties, the reliability of these structures evaluated. In this project for... 

Double angle connections, which are welded to the beam web and bolted to the column flange, are usually used to make hinged or semi-hinged connections. Several models are presented in this study whose geometrical properties are different. The finite element software package is used to develop the finite element analysis of the connections. An analytical method is presented that can be used to determine the behavior and deformation for this type of connection. The correctness of Moment-rotation curves of finite element analysis for each connection has been ascertained by comparison, using analytical technique; and a very good agreement has been obtained  

This thesis presents the investigation and development of a Finite Element Model (FEM) for a new type of Beam-Column Semi-Rigid steel connection. One of the main parts of this connection is a steel T profile inserted on top of a beam connecting it to a column by bolts. It seems that changes in the geometry of the T profile and its bolt positions can have a great influence on the rigidity or flexibility of the connection. Therefore, meaningful categories of the T profile geometry with different bolt positions have been modeled and analyzed by means of a Finite Element Modeling software ABAQUS, and their moment-rotation curves were driven. Also the Initial and Nonlinear Stiffness and the... 

Reinforced concrete shells are widely used to cover the small to large area with more aesthetics at minimum cost. Shell structures carry load through their shape rather than material strength. Funicular shells are special type of shells that their shape is obtained so that stresses be compressive under a special load (for shell, this load is its dead weight). This study deals with geometrically nonlinear vibration of funicular shells on a rectangular ground plan under impulse loads using nonlinear shallow shells theory. The boundary conditions are considered as clamped edges. Displacement components are product of position and time functions. The analysis is based on the expansion of... 

Reinforced concrete shells are widely used to cover the small to large area with more aesthetics at minimum cost. Shell structures carries load through their shape rather than material strength. Funicular shells are special type of shells that their shape is obtained so that stresses be compressive under a special load (for shell, this load is its dead weight). This study deals with forced vibration of funicular shells on a rectangular ground plan under impulse loads using shallow shells theory. Two boundary conditions, simply supported and clamped, are considered. Displacement components are product of position and time functions. The analysis is based on the expansion of displacement... 

Nowadays population growth, people housing demand and urbanization tendency has increased the land and house prices. So the constructers tend to build apartments. Time consuming and heavy costs of building and renovation has made the owners to rebuild the damages of their houses in case of an accident. Time and cost are the main factors in construction which includes rebuilding. Buildings and especially apartments renovation is expensive and prolonged. So the rebuilding tendency has been noted more than ever. In this study it has been tried to control costs and time by efficient management to save the rebuilding time and money. Two kinds of questionnaire has been applied to study different...