Sharif Digital Repository

Observations made after previous earthquakes have shown the crucial role of irregularities in initiating damage in buildings with irregularity, either in Plan or in Elevation. Since in existing Building Codes, there is no provision for the distribution of the Equivalent Static Loads for such buildings, designers have no option but to resort to Dynamic Analysis. In this work, the seismic behaviour of a group of two-dimensional steel building structures with irregularity in elevation, namely Split-Level buildings, was studied. The studied structures consist of a series of 5- and 15-storey frames having two parts with splitting distance of 150 cm. Both, moment-resisting and braced frames were... 

Due to the wide application of Mass Concrete in the body and the foundation of dams, foundations of tall buildings, industrial machinery, and power plants, foundation and piers of bridges, etc.,it is necessary to devise methods in order to prevent the adverse effects of the high volume of such concretes. Since the major negative outcome of high volume is the decrease of the strength of concrete, which in turn is the direct consequence of the cracks resulted from high increase in the temperature within the volume of the concrete as a result of Hydration process and the produced heat which remains inside the bulk of concrete, any solution should involve some form of transferring the heat to... 

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... 

Due to the important role of base plates, both in transferring forces from the structure to the foundation, and also in transferring vibrations from soil to the structure, it is necessary to have sufficient knowledge on their behaviour and performance under monotonic and cyclic loading regimes. In fact, the behaviour of the supports of any structure cannot be identified without identifying the behaviour of its base plates. Numerous configurations with/without various types of attachments have been proposed and used for base plates. In this work, altogether six commonly-used types of base plates were studied and their behaviour under monotonic and cyclic loadings was obtained using commercial... 

Past earthquakes show that irregular structures have been more vulnerable than their regular counterparts. One of the common types of irregular buildings in urban areas is split-level ones. On the other hand, beam-to-column connections in steel structures are mostly of "semi-rigid" type. In this work, effects of different levels of rigidity of connections, 100%, 75%, 50% and 25%, on the behavior of a number of two-dimensional split-level steel structures, with 1.5 m difference in levels of floors, 2, 3, 5 and 6 bays, and 5, 10 and 15 stories, were studied. All frames were analyzed “with” and “without” considering the P-∆ phenomenon, with two methods, ‘equivalent static load,’ and ‘modal... 

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... 

The objective of this project is to study the behaviour and performance of an innotative floating offshore platform. Such Platform not only can be used for exploring oil from offshore fields, but for creating artificial islands, where land is in short supply. Due to its specific and, at the same time, simple geometry (symmetric), its fabrication does ont involve much complexity. Studies carried out on this platform include the investigation into its structural behaviour under gravitational (including self weight) and bouyancy forces. Studied cases include a number of platforms with different (geometrical) sizes and under 3 various bouyancy conditions (percentage), namely 1) 50% of the height... 

With the growing of smart device softwares, the speed of applications and energy consumption has become a concern for developers of smart device. The unobtrusive running of applications, when the smartphone processor is occupied, alongside the energy issue, when the user needs an urgent need to use a low power storage device, is of concerns for the use of these devices.In order to overcome this issue, cloud computing platforms, transfer smartphone tasks and duties to the cloud platforms and retrieve the results of the calculations to the phone.Obviously, communicating with the cloud requires a communication channel. The communication channel for the internet can either be the internet in... 

Study of former earthquakes damages reveals that irregular structures are more susceptive to failure than regular ones. Irregular structures are classified into two categories, namely those with irregularity in elevation and the ones with irregularity in plan. Besides, one of the crucial parameters in working out the earthquake’s equivalent static load is response modification coefficient (R). Based on the type of seismic lateral force-resisting system, this parameter can have various values. In this research, using nonlinear static analysis, the response modification coefficient of a great number of 3-D steel frames of 5, 7 and 9 m spans and having 1 to 10 stories with various... 

Bracing Systems are usually a set of inclined members that are embedded in structures to resist lateral forces and control lateral displacements. There are different types and behaviors for Bracing Systems depending on the way of assembling and locating them in the structure. Braced Frames, such as Concentrically Braced Frames (CBFs), generally have high stiffness and low ductility. Another Type of Braced Frames is Eccentrically Braced Frames (EBFs) which improves CBFs by establishing suitable ductility as well as stiffness. Inelastic behavior of Links involved with EBFs caused this in EBFs. Nevertheless, these systems have no efficiency in next earthquake, because links are parts of beams... 

The behavior of a new steel shear wall, already devised by the supervisor of this project, and tested by other students, was modeled numerically. Such numerical simulation was carried out using the Finite Element Methods of analysis. Hexagonal solid elements were employed in order to discretize the tested specimens and those parts of the test assembly which had to be included in the models. Both, Monotonic and Cyclic tests were simulated numerically. Comparison of the tests results with those of the numerical models showed fair correlation between them. Percentages of error in the dissipated energy for the three monotonic tests were 6.9%, 6.4% and 11.2%, respectively, whereas that of the... 

The behaviour of a semi-rigid connection with appreciable shear deformation capacity was studied experimentally. The tests carried out on the specimens of this connection composed of ‘monotonic’ and ‘cyclic’ tests. The monotonic tests results showed the high shear deformation capacity of this connection as well as its high energy dissipation capacity. The cyclic tests, however, indicated the ability of this connection to endure large number of ‘well-rounded’ hysteresis cycles, which led to the dissipation of great amount of energy before failure  

In this thesis, change of the behavior of frames due to adding damping devices to frames is taken into consideration and a non-linear static analysis computer program is developed . In numerical studies a few one and two story frames are used. The results of previous studies have shown that, adding energy damping devices to the structural systems, results in structure damping increase, story drift and base shear decrease. To reveal the behavior of the new bracing system, experimental and numerical studies are made. The main point in design of this bracing system, was the capability of easy replacement and maximum damping with minimum damage. It must be declared that design thought of this... 

Abstract- Due to vulnerability of metallic structures to fire, to have an advance estimate of the behaviour and performance of the structure during fire, can greatly assist the designers to make preparations and take precautionary measures to prevent excessive damage to the building. The study of the behaviour of a structure at high temperatures can be divided into two parts, that of its members, and that of its joints. The survey of the literature reveals that most of the previous work concentrated on the former, and it seems that there has not been much work on the latter. The objective of this project was to study the behaviour of structural joints at elevated temperatures, in general,... 

Low tensile strength and also low strain capacity make plain concrete a ‘brittle’ material. To overcome this shortcoming, the addition of fibre as a reinforcing material has proved to be a reasonable solution. One of the crucial factors in deciding to make this type of concrete is the cost of fibre, which varies depending on its type. In this project a special type of fibre which does not cost a lot and at the same time has a high strength has been used. To investigate the effect of the fibre on the tensile strength of concrete, splitting tensile test (Brazilian test) was adopted. Altogether, 30 standard cylindrical specimens with dimensions of 15 × 30 cm2 were made (3 of each type) which... 

Semantic Holism is one of the most effective and wide spreading topics in philosophy of language. W.V.Quine with his “Two Dogmas” article has coined semantic holism with his name. After Quine, semantic holism absorbed many attentions in the philosophy of language and also other fields. Even, in neural networks and artificial intelligence, holistic presumptions about meaning are accepted. Nevertheless, arguments for meaning holism and their validation has not tended enough. Fodor and Lepore, in Semantic Holism; A Shopper’s Guide, are trying to reconstruct arguments for semantic holism that had been presented by philosophers like Quine, Davidson, Dennet, Lewis, and Churchland and then... 

Studying the performance of irregular structures in past earthquakes reveals that due to their severe vulnerability, we need to accurately assess the behavioral characteristics of such structures. On the other hand, all existing seismic codes recommend the use of response modification factor to determine the base shear, design forces of the members, and the design drift ratios, which seem to have limited comprehensiveness. Moreover, the response modification factor for a structural system is discussed in a general manner and the effect of factors such as number of bays, number of stories, span length, story height and irregularities are not considered. In this research, the effects of... 

Regarding the advantages of steel shear walls compared with other lateral load-bearing systems, the need for having better knowledge on their performance becomes more obvious. While much study, either theoretically or experimentally, have been conducted on these systems in the past, less attention has been paid to their nonlinear behaviour. This has happened where in many practical situations some parts of such systems experience nonlinearity. Therefore, it is necessary to study the nonlinear behaviour of such walls either individually or as part of a framing system. In this project, using Finite Elements Methods (FEM), the behaviour of a number of samples of an innovative steel shear wall,...