Sharif Digital Repository

Adobe buildings on one hand are very heavy and hence generate great amounts of inertia loads during earthquakes. Their response is also amplified in the high-frequency earthquake waves due to great stiffness. On the other hand, these structures proved vulnerable during past earthquakes because of low strength and ductility. Considering the fact that there are too many structures of this kind throughout the country and a majority of their residents are the poor, seismic retrofitting of these building should be taken as a priority rather than reconstruction. It is obvious that the proposed retrofitting technique should be simple, feasible and economical, as well. Among possible retrofitting... 

Although the moment frame can show deformable behavior against seismic loads, but its flexibility and low stiffness, especially in tall structures, cause the governance criterion to be designed. The use of eccentrically braced frames was able to solve the displacement problem to some extent, because it has the characteristics of both flexural frame systems and conccentric bracing. Different methods have been proposed to eliminate residual displacements in this type of system, one of which is the use of post tensioned cables. The aim of this study was to investigate the seismic behavior of a steel structure with a eccentrically braced frame system with post tension cable.The cables are anchor... 

One of the lateral-load bearing systems that has been recommended since almost 40 years ago is the steel plate shear wall (SPSW) system, which consists of a steel plate surrounded by beams and columns in each story. As for the performance of SPSWs, it is assumed that the boundary members of the wall’s plate, i.e. beams and columns, have sufficient stiffness and strength, so that they would not yield by the tensile stresses exerted due to the post-buckling behavior of the plate (tension field); and the global stability of the structure is still maintained. This assumption leads to significantly increased dimensions of the sections applied in the wall’s boundary members, particularly its... 

Many reinforced concrete frame buildings with masonry partitions have been built all around the world. Observations from past earthquakes show that the partitions can endanger the life of buildings occupants and lead to significant damage and loss. Failure of the partitions can be caused by dynamic vibrations and in-plane and out-of-plane loads/displacements. The interaction between in-plane and out-of-plan behaviors and location of partitions, nonlinearity and higher modes of the structures could affect the out-of- plane seismic demands on partitions. Therefore, there is a need for a comprehensive assessment in order to limit the loss in buildings with masonry partitions. This research... 

The aim of this study is to evaluate the seismic performance of structures using a semi-active tuned mass damper minimizing the amount of structural damage caused by earthquakes. One of semi-active control mechanisms, which has been studied in recent years, is the damper with fluid controlled by a magnetic field (Magnetorehological Damper, MR). These type of dampers react to the magnetic fields that cause significant changes in the behavior of fluid flow. These dampers are acknowledged because of their simplicity, broad operating range as well as not requiring high-power energy sources. In this thesis, a MR damper is used instead of the existing viscous element of tuned mass damper. To... 

During an earthquake, if the seat width provided at the joint is less than the relative joint opening, the bridge’s superstructure becomes unseat which leads to potential collapse due to the lack of support. Because of the catastrophic consequences of loss of support and the perception that the damage could easily be prevented at relatively low cost, some retrofitting programs focus on preventing such failures involved the addition of longitudinal restrainer cables and bars to limit the relative movements at expansion joints. Noticing the weaknesses of usual restrainers including the transmission of excessive forces to substructures, weak capability of energy dissipation during severe... 

This research studies behavior and implementing of telescopic lead shear damper in structures. Telescopic lead shear damper (TLSD) is a type of metallic yielding dampers that can dissipated energy with usage of shear yielding of lead. TLSD is made from behind act of two lead shear damper (LSD) like a telescope. Lead shear damper composed of two coaxial steel pipes where their interfacial gap is filled with pure lead. The interface of lead and steel pipes are roughened in a threaded form to guarantee the no-slip condition across the interface. Due to stable and fat force displacement hysteresis loops of TLSD, this device can be used in structures subjected to wind, seismic, and other dynamic... 

This study aims to parametric study and model steel joints with side plates. steel joints with continuum plates have been seismically acceptable for years, assuming they are designed to be stronger than beams. After the Northridge earthquake, the belief that the adequacy conditions of flexural frame joints were limited to stiffness and strength factors was challenged for two main reasons. First, at the junction of the beam with the column, high tension is created by the seismic force, and as a result, it buckles and loses its strength before reaching the projected force. The second problem is due to the problem of making such connections that it is difficult to weld. Therefore, the problem... 

Iran plateau is situated over the Alpide-Himalaya earthquake belt. Tectonic studies indicate that this plateau has a very high density of active and recent faults; as a result, Iran is at risk of damaging earthquakes. Experience of past severe earthquakes shows previous designed structures do not have enough strength instead of real earthquake forces, therefore vulnerability study of existing structures and give a technical and economical retrofitting plan of them is required. Conventional methods of seismic rehabilitation for example using concrete shear walls or steel braces are not suitable for some buildings. Nowadays, passive control systems have been successfully used for reducing the... 

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... 

Steel structure with saddle connections constitutes a portion of the old steel structures in Iran. During past strong ground motions such as Manjil and Bam earthquakes, these structures were vulnerable and experienced significant damages. These structures were widely used due to their easy installation. However, according to their unpromising behavior, they need an appropriate lateral force-resisting system. A concrete shear wall is one of the suitable lateral force resisting systems that can improve the behavior of steel frames with saddle connections. To find the coefficients of seismic performance factors including response modification factor, overstrength factor, and deflection... 

This thesis studies the effect of soil-structure interaction on the seismic performance of structures with due account of uncertainties. The motivation for this study stems from the significant uncertainty in the earthquake ground motion and in the properties of the soil and the nonlinear behavior of the structure. The soil-structure system is modeled by the sub-structure method. The uncertainty in the properties of the system is described by random variables that are input to this model. Monte Carlo sampling is employed to compute the probability distribution of responses that describe the seismic performance of the structure, such as the ductility demand. In each sample, a randomly... 

The objective of this study is to design a real structure based on value using the endurance time method, which is designed according to common design codes. In the value-based design of this structure, a variation of the lateral load coefficient has been used for the design of the investigated structural specimens. The term "value" in this research refers to the total costs incurred over the lifespan of the structure. The initial construction costs of the structure and the life cycle costs are optimized in the value-based design process. The initial construction cost in this research consists of two parts: the first part is variable costs that arise from the consumed materials in the... 

In recent years a large number of passive energy dissipating systems developed in accordance with pioneering work on friction dampers which was firstly reported by pall(1979). Uusing Friction dampers reduce the inelastic demand of the structure during severe earthquake motions by sliping and a large portion of input energy dissipated mechanically in friction instead of yielding the main components of the structure. Based on economical purposes, it is valuable to know in which storey and slip force should be employ the friction devices to have an optimized performance of the structure. Due to kinematic conditions of slip and stick stages, as well as transition zones between them in friction... 

In this paper the predictive equations for collapse assessment of shear links used in eccentric braced frames are developed. An extensive database including results of over 70 cyclic tests on steel wide flange shear links is collected and the structural parameters governing the hysteresis behavior are calibrated using a simplified numerical model. The methodology of calibration is to minimize the discrepancy between the experimental hysteresis loops and the corresponding numerical results using Particle Swarm Optimization (PSO) algorithm. The objective function of PSO algorithm is minimized by iterating parameters that govern the hysteresis behavior of the numerical model. Stepwise... 

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,... 

This thesis contains experimental studies on mechanical properties of adobe and mud material and investigating seismic performance of a conventional adobe house using shake table tests. Mechanical properties of adobe and mud material were studied experimentally based on ASTM and BS standard tests. These experiments were designed to evaluate compressive strength of adobe sun-dried blocks and mud mortar cubes. Besides, shear behavior and tensile bond strength of adobe assemblages were under consideration and shear tests were done on adobe panels. As next part of the research, several shaking table tests were conducted on a dome-roof adobe house as a conventional representative of arch-roof... 

In this research a novel steel connection, named “Doubly Reduced Beam Section”, and a new design procedure for “Reduced Flange Plate (RFP)“ connection are introduced and their seismic performance under cylcic loading is assessed. In order to avoid repetition of calculations, reducing human error and time consumption a computer design file in Microsoft Excel Program has been developed. Then along side the evaluation of the cyclic behavior of the connections utilizing the Finite Element Method (FEM analysis), a parametric study of the influence of various parameters on the connections seismic behavior is carried out. The results show that, following the limitations and guidelines stated in... 

This thesis is concerned with the performance of heavy equipments like electric substation transformers and bushings under earthquake loading. It begins with the description of the transformers, attached bushings, and some typical examples of substation failures in earthquake loading. This is followed by the field test and development of numerical models of transformer and two different types of seismic isolations, Natural rubber bearings (NRB) and high damping rubber bearings (HDRB) and in order to find the appropriate isolator, responses of fixed base and isolated transformers are compared. Important observations were made on the seismic responses of the transformer and its bushing.... 

The present parametric study discusses the effective factors on seismic performance of spherical RC domes. For this perpose, a series of domes with different spans, a variety of contact angles (the angle between the bottom of the sphere and the center of the sphere), openings with different areas and various support condition are studied. Then the value of response modification factor and it's components is determined to take into account the effect of each component. The results obtained indicated that the response modification factor increases as the contact angle enhances. However, the span of domes insignificantly affects the value of response modification factor.also analysis on domes...