Sharif Digital Repository

The objective of this study is to assess seismic vulnerability and more specifically to develop analytical fragility curves for a number of existing buildings in Qazvin. Fragility curves represent exceedance probability of the structural response from a specific limit state at a given seismic intensity level. In this study, Maximum Interstory Drift Ratio and Spectral Acceleration at fundamental period of the structure with 5% viscous damping are considered as Damage Index and Intensity Measure, respectively. Limit states are also applied as it is suggested in FEMA 356. In order to obtain comprehensive and extensible results as far as possible, the type of buildings under study must be... 

It is well known that the most rigorous method to assess the performance and to predict the seismic demands of a structure subjected to earthquake is nonlinear time history analysis. However, this technique is accompanied by complexities and difficulties in evaluating the seismic demands of structures and requires superior knowledge and skill. As a result, in recent years, nonlinear static analysis has been proposed in performance based design procedures. One of the primary assumptions of nonlinear static procedures is that the behavior of a structure with multiple degrees of freedom (MDOF) subjected to seismic ground motion can be estimated from the response of an oscillator with a single... 

The objective of this thesis is to evaluate and calibrate design load combinations of steel building structures of Iran based on the reliability theory. The importance of this research stems from recognition that the design load combinations for steel structures in Section 6 of the National Building Code of Iran have been completely adopted from the ASCE/SEI 7-10 standard, whereas the factors that affect these load combinations differ in Iran from those of the United States. Examples are the difference in the construction industry economy, lower quality of here and the differences in probability distributions for the specifications of steel. Hence, the load combinations need to be calibrated... 

Most regions in Iran are located on an active plate boundary. Therefore, many parts of the country face a risk of earthquake damage at some point in time. Therefore, anticipating and addressing the consequences of earthquake events in order to minimize loss of life and damage to property is a national issue.There is concern about the ability of a signification fraction of buildings in Iran to withstand earthquake events. The deficiencies in the design and construction of buildings in Iran result in low-quality buildings vulnerable to earthquakes. It is necessary to identify and investigate the parameters that contribute to these deficiencies.Previous research studies indicate that... 

Fire is one the events which threatens the very existence of every building, residential, office, industrial or else. However, this threat is more serious with regard to buildings with steel structures. Steel, despite its many advantages over other structural materials, such as having high strength to weight ratio, ductility, toughness and resilience, has the disadvantage of rapidly losing its strength at elevated temperatures, i.e. in fire. Therefore, it is the responsibility of the designer to make the serious decision of whether to use steel, concrete, timber, or other materials for the structure of the building to be designed. Observations made during full-scale fire tests as well as... 

Shape memory alloys (SMA) are materials with shape memory effect and high recentering capacity. Recently, application of SMAs in building structures and for the purpose of structure control during earthquake has been considered by many researchers. Researchers have tried to reduce the residual displacement of the structure after earthquake and also increase the dissipated energy by using this material in different forms such as wire, spring, bolt, etc.. In this research the seismic performance of steel structures equipped with SMA connection has been studied, considering the soil and structure interaction. The purpose of this research is to investigate the amount of required SMA bolts in... 

The purpose of this research is to study the behavior of some kind of conventional and retrofitted Khorjini connections, such as stress and strain concentration and eventually strain-jumping phenomenon. Thus the software ABAQUS 2019 was used to fabricate the FEM models of the connections with experimental prototypes. In analytical studies, 21 specimens with different sizes of the connection components were analyzed. True stress-strain curves for steel and weld materials were used and damage initiation and revolution were considered in the weld material. Also cracking of the welds was considered by a micromechanical method. The main defects of the connection are severe initial stiffness... 

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... 

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... 

In this study, several novel cable-pipe damper brace (CPDB) systems are introduced. The CPDBs consist of steel cables wrapped around supporting pipes and arranged as cross-bracing in steel frames. The arrangements are such that the cables are always in tension when a lateral load is applied to the steel frames. The wrapping of cables around pipes makes the systems act like a friction damper in a seismic event. In addition, the possibility of energy dissipation by plastic pipe deformation and yielding of cables is investigated. Each system is analyzed by nonlinear finite element method to investigate its lateral strength and cyclic behavior. The primary results of this study showed that some... 

The response modification factor (coefficient of behavior) of structures (R) is a parameter that is used during their design using the linear static analysis method to account for the effects of the non-linear response of the structure considered. Therefore, the existing seismic codes consider it necessary to use the R factor during the design process. In addition, for each family of structural systems, the Codes propose a specific R factor in a very general manner. In this project, an effort has been made to obtain and propose a correct, relatively accurate, and logical coefficient of behavior for two-dimensional steel frames equipped with a special type of bracing. In this regard, the...