Sharif Digital Repository

The purpose of this study is to determine the effects of some strengthening methods such as steel jacketing, concrete jacketing and FRP wraps in the overall behavior of structures and introducing the most appropriate method. For this purpose a 14 story building with intentionally weak designed shear walls was considered, subsequently each of the strengthening methods were followed for the shear walls and relative structural outcomes like total stiffness and lateral movements were calculated, studied and compared and finally a guideline for choosing the most appropriate strengthening method for concrete shear walls is resulted. It is established that for the system with steel jacketing... 

Recent earthquakes indicate the importance of retrofitting existing structures to achieve an acceptable level of performance. Use of bracing systems is a cost-effective method for seismic retrofitting of existing steel frames. In particular, Buckling Restrained Braces (BRBs) and Special Concentrically Bracing systems (SCB) are practical choices to be used because of their large energy dissipation capacity especially under moderate to severe earthquakes. Buckling restrained braces which yield in both tension and compression, exhibits stable and predictable hysteretic behavior. In this study several existing steel frames, which are designed based on older versions of the building codes, have... 

Recent investigations on construction engineering have determined that repairing of Reinforced Concrete (RC) by means of fiber reinforced polymer (FRP) composites is an effective method of retrofitting existing columns. The main research in this thesis focuses on the repair of concrete specimens which are damaged and their initial strength has been reduced. To achieve this purpose, through experimental procedures, the effect of confining damaged concrete cylinders by FRP, has been investigated. The experimental program included three parameters: type of fibers (glass or carbon), type of confining (full or partial), and the number of layers. First concrete cylinders were made and loaded to... 

Among different natural disasters, earthquake has always been known as one of the most effective ones on human lives, and this is only because we still cannot predict the exact time and place of its happening. So, giving special attention to the methods which can omit or minimize the damages of this natural event is needed for controlling the loss in the event of an earthquake. On the other hand schools are known as places which are full of people from younger ages for at least half of each day, and they are considered to be not well educated about how to react in an earthquake in comparison to older people and also considered vulnerable at the time of this natural event. According to what... 

The aim of this research is retrofit of a crude oil distillation refinery unit in terms of water and energy. To do this, the refinery distillation unit is ategorized to different zones from the perspective of water and energy to determine the saving potentials. The energy network consists of the four sub-types includes exchangers and the water network consist of seven sub-sets including water and steam. In the next stage, the retrofit of the energy network and the process heat exchangers are done by using pinch analysis in the commercial software and discussed the economical possibility of pinch analysis for 20 heat exchangers in the crude oil preheating unit. Using the flow of flashed crude... 

Distillation is the most applied unit in the separation processess of the oil and gas industries. Because the distillation process requires energy in the form of the utilities, integration of heat pump systems in the distillation process as an application of these systems is considered in this research. A new and effective methodology of proper integrating of heat pump and distillation columns has been proposed by collecting thermodynamic and thermoeconomic tools. Then, this procedure has been applied on the ethane recovery and NGL fractionation units of 4 & 5 phases of the south pars field. The exergy analysis of the distillation columns is the first step of this methodology as the... 

Characterizing cellular states in response to various disease conditions is an important issue which is addressed by different methods such as Large-scale gene expression profiling. One of the most important challenges in front of bioinformaticians is the loss of data because expression profiling is still very expensive. It is understood that profiling a group of selected genes could be enough for understanding all of the gene expression profile.In this research, we propose a fast method for estimation of the missing values inlow-rank matrices. We consider the highly correlated expression profiles as a low-rank matrix. Then, we used this new method in a proposed algorithm which will select... 

This study proposes a probabilistic approach to prioritize a collection of buildings in a region for seismic retrofit based on regional risk analysis. Risk in this context is the exceedance probability of total economic and social losses, which include both direct and indirect consequences resulting from building damage. The prioritization criterion is determined by the benefit-to-cost ratio of retrofit, where the benefit is measured by the reduction of seismic risk achieved through retrofitting. Hence, the buildings are analyzed both in their current state and after retrofit to compute the risk measure, i.e., the mean total loss. Buildings that yield the highest reduction of the risk... 

This thesis presents a probabilistic framework for prioritizing the highway bridge network for seismic retrofitting and structural health monitoring. The basis of this framework is the risk analysis of the bridge network, which includes bridges and the links connecting them in the transportation network. Risk is defined as the probability of exceeding the sum of all losses incurred to the community in the event of a hazard. These losses include the direct economic cost of bridge repairs and damage to vehicles due to bridge failure, the socioeconomic cost of increased travel time for transportation network users, the indirect economic cost of excess fuel consumption and depreciation of... 

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... 

The purpose of this research is to study the effect of using expanded polystyrene (EPS) Geofoam to retrofit buried pipelines in slopes subjected to landslide due to earthquakes.For this purpose, several 3D numerical models were built with ABAQUS/CAE based on physical model tests conducted on shaking table device at Sharif University of Technology by previous research groups. Two parts are considered in this study. in the first part, three tests were simulated. Displacements, acceleration time histories and strains of pipes were compared to the tests results and the effect od EPS block on each pipe pesponse was observed. In the second part, effect of two factors on response of buried pipes... 

In order to investigate the behavior of unreinforced masonry buildings and the effects of shotcrete retrofit, a half-scale one-story masonry building was constructed and tested on the shake-table of Earthquake Research Center at Sharif University of Technology (SUT), Iran. The project was jointly founded by SUT and Ecole Polytechnique Fédérale de Lausanne (EPFL), with the support of The Organization for Development, Renovation, and Equipping of Schools of I.R Iran (DRES). The 3.7×3.7×2 [m] specimen was modeled after a typically built classroom, with eccentric window openings on one wall and a door opening on the opposite wall. The walls were constructed using half-scale 10.5×5.0×2.9 [cm]... 

This thesis intends to evaluate the effect of landslides on dynamic response of soil slopes and buried pipelines. The core findings of the research are itemized as below: According to the experiments, dynamic slope response which moderately develops at deeper depths at toe and lower section, displays a clear downtrend at upper section and crest. Also, the pipe response depends on pipe route and slope displacement pattern. The pipe deformations have positive correlation with depth at upper section and crest, but show opposite behavior at toe and lower section. Moreover, the horizontal strains impact on total strains in buried pipes reduces at greater depths.The pipe strain analysis shows that... 

Infrastructure systems play a critical role in the economic and social activities of a community. Effective and continuous performance of these infrastructure systems is essential to the welfare and prosperity of the communities. Infrastructure systems comprise networks of interdependent assets that are built through a long and costly process. These assets are subject to a variety of factors that reduce the performance and reliability over time. These factors also increase the vulnerability of infrastructure assets in face of future probable hazards. In order to ensure the continuous and uninterrupted performance of infrastructure assets in post-hazard situations, asset managers should plan... 

The aim of this research is presentation of A framework to select the appropriate combination of retrofit and insurance in order to reduce earthquake losses. The vulnerability of buildings to earthquakes can lead to significant damage to owners and residents of these buildings. It is imperative that appropriate measures be taken to reduce these adverse effects before the risk occurs. Some of these measures, such as seismic retrofit of buildings, can reduce the vulnerability of buildings and, consequently, financial and human losses. Some other measures like insurance, in the event of an earthquake, can reduce the financial losses incurred by owners and residents of vulnerable buildings.... 

Occurrence of natural disasters such as earthquake could seriously damage most buildings especially those with insufficient resistance located in urban worn-out textures. In order to reduce unpleasant consequences of an earthquake, appropriate policies need to be considered to persuade the beneficiaries to follow retrofitting standards in the process of planning, designing, and construction of buildings. These policies shall be implemented through institutions in arbitrary or obligatory forms, by encouragement or penalty mechanisms. In order to consider these policies, first of all we need to identify the beneficiaries and their particulars. By studying and considering subjects discussed in... 

Studying of slope stability under dynamic loading such as earthquakes is one of the critical issues. This importance is attributed to many of the slopes are located in urban areas, either around them or in the important buildings and infrastructure. Thus, evaluation of slope’s behavior is very essential. On the other hand, preparing fundamental arrangements to improve the current situation, surrounding and buried areas in the slope is necessary.
In this study, a physical model of Tehran's slopes by 0.1 ratio with pipes that have been retrofitted by plastofoam developed. This model was tested on the shaking table under dynamic loading. The dimensions of the slope were 1 meter width, 3... 

Offshore platforms are one of the most important structures in oil-rich countries, so that their economic benefit makes it very expensive to stop their usage. Therefore, it is essential that their performance is not disrupted by earthquake or the tidal waves made by severe storms. In the conventional bracing systems, it is assumed that the braces buckle under compressive forces; but Buckling Restrained Brace (BRB) does not buckle under pressure. In this study performance of BRB in jacket platform, with a case study of Resalat platform, has been investigated under earthquake load and powerful wave. The modeling of jacket equipped with this brace has been done in Abaqus software, and results... 

Retrofitting and strengthening existing structures is one of the most important concepts of structural and earthquake engineering. Strengthening of structures could be due to changes in application and applied load, errors in calculation, mistakes in construction, weakness of old codes, structural height increases and changes in environmental conditions. Different methods for increasing the flexural strength and ductility of reinforced concrete beams, as one of the major structural components, have been presented. This research presents an experimental study on the strengthening of reinforced concrete beams by reinforced concrete jackets (classical method) and Fiber Reinforced Polymer (FRP)... 

Concrete structures may become weak and damage due to different reasons and need retrofitting or strengthening. Strengthening means increasing strength and resistance of members that injured to resist the design loads. The weakness of these structures may due to change in the design code provisions, administrative error, change in the usage of the building and damage caused by different events. In the last decade substantial research has been conducted on this field most of which were on the upgrading of RC beams under different loading. There are few studies in strengthening works of RC beams under static loads of torsion. Most researchers in this field have been used polymer fibers to...