Sharif Digital Repository

Buried pipelines might pass slopes that are stable in static condition but slope dicplacements due to dynamic loading can result in pipeline failure. There are various factors that influence 3D slope stability under seismic loading condition.In this dissertation , we used finite element software ABAQUS (ver.6.10) to study pipeline performance in such condition. Dynamic analysis on pipe with burial depth of 1.5m that passes a 3D slope was performed by using the time history of sinusidinal loading. Boundary conidion of slope and pipe affects the slope dicplacement and pipeline performance. In different routes that pipe passes slope, pipeline response to slope displacement has been compared... 

The abstract is the most important section of the thesis because many readers limit most of their reading to abstracts, saving in-depth reading for specific theses. It should give the reader a "preview" of what's to come. The abstract should emphasize new and important aspects of the study or observations. The purpose of the abstract is to allow researchers to decide whether or not to read the whole thesis. The abstract is what researchers read first to decide if the thesis is important, interesting, and it allows them to assess the relevance of a thesis to their own research, without having to read the entire thesis. Thus, it is crucial that the abstract both summarize succinctly the key... 

In this study, the changes in the mean vector and the covariance matrix of engineering demand parameter (EDP) distributions for different intensity measures and ground motion selections is evaluated. Although, the changes in the mean distribution of EDPs have been extensively studied in the literature, but the changes in the covariance matrix of EDPs distributions caused by ground motion selections has not been paid the due attention. In other words, no study has specifically looked into the effect of intensity measure changes on the covariance matrix; therefore, for the purpose of this study, several steel frame models were considered with perimeter special moment resisting frames (SMRF).... 

In recent years, the application of base isolation as a seismic design strategy for reducing the effects of earthquake ground motion has become an advantageous method and much effort has been devoted to base isolation research and there has been a growing acceptance of this approach. In this research, the effect of using base isolators in reducing the dynamic forces of piers and abutments of bridges is studied. More specifically double-span bridges are the target of this research. After modeling a regular bridge in a typical analysis program, it is excited by different earthquake accelerograms and then the effect of using base isolators in dissipating the earthquake energy is investigated  

Due to structural and nonstructural damage after the occurrence of Northridge 1994 and Kobe 1995 earthquakes, Seismic design basics was modified and philosophy of performance based design was suggested. In this novel solution, Predefined limitations are considered. Performance criteria were usually related to displacement or other correlated factors such as hinge plastic rotation. All the mentioned limitations are related to different damage states.Most of the codes and articles use following assumptions for assessing structural performance: 1) considering first vibrational mode for structural response to any seismic excitation regardless of seismic input acceleration records or structural... 

Since 1906, after the earthquake of Messina in Italy, Italian engineers start developing a new method for increasing the resistance of a structure during an earthquake. With the limitation of time and technology, this method was acceptable for the time period. By developing the accelerographs and seismographs and the methods to process big data, new methods are developed and are being used in designing structures; new technologies allow engineers to analyze the performance of structures with ease. The studies in this research indicates that achieving the safety indices in any design require utilizing all dynamic properties of a structure such as period, stiffness and damping. In this... 

Nowadays, proper design and retrofitting of structures against natural and manmade disasters, is among the main concerns of researchers and designers in order to reduce financial and human costs. Extensive research has been carried out on the structures resistance against earthquake up to now. Although, the vast amount of research has resulted various regulations and guidelines, there is still a long way ahead to achieve the desirable results. Due to high sensitivity of the steel to temperature variations, fire exposure is more destructive for steel structures compared with the concrete ones. The performance of an intermediate three-storey steel moment frame with 4 spans was studied in this... 

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... 

Earthquakes can cause significant economic damage to society. These damages include direct economic damage, ie, the cost incurred by the community to rebuild damaged infrastructure. In addition, damaging the infrastructure, the earthquake reduces the level of infrastructure service, and thus, disrupts the businesses that rely on it. The consequences of such disruptions, such as a decline in the level of productivity and efficiency of firms, or an increase in the rate of unemployment and migration from the community, can cause indirect economic damage to society. The costs incurred to society by disasters can be reduced by adopting appropriate solutions. In many cases, however, the incentives... 

The main purpose of this research is to evaluate the impact of mainshock and aftershocks on the response and fragility of power transmission towers and to provide an approach to assess the risk of transmission lines under mainshock-aftershock sequence. The transmission line studied in this research has 27 self-supported 400 kV transmission towers. The reason for choosing this line is the proximity of the line to the active faults of Tehran like Mosha and North-Tehran, as well as the service of the line to a large residential and industrial area, which, in case of damage by an earthquake, will cause considerable direct and indirect loss to the society. In the three-dimensional models... 

The aim of this research is inroducing appropriate intensity measure to improve the ability of endurance time dynamic analysis to estimate the seismic response of structures and structure response distribution function. In endurance time method, the structure subjected to intensifying artificial accelerograms and we’ll find structure responses at different return periods just by one-time seismic analysis. Also, according to the high computional time of other dynamic analysis’s, the endurance time method is used which decreases the computional time simultaneously the dynamic predicted responses are accurate enough. In this way, we have a concept known as goal time which is duration of... 

Near-Field earthquakes have gained so much attention through their catastrophic consequences on structures in the vicinity of seismic sources during recent events. Based on recorded data, it is understood that these kinds of phenomena are often accompanied with a large energy pulse at the first times of record whose impulsive characteristic is primarily caused by “forward directivity”. Incapability of response spectra for depicting great demand for energy dissipation disqualifies this method for utilization. Thus it seems inevitable to analyze the models prone to this kind of hazard using time-history based analysis. Being simple enough in time domain, raises hopes for finding a mathematical... 

The necessity of providing synthetic acceleration records suitable for seismic assessment of the structures in the regions whose seismological history has not enough instrumental recordings has become one of the main concerns of the earthquake engineers. Despite being accurate in estimating earthquake ground motion, physics-based methods involve complicated procedures and need the detailed information about source, path and the site conditions of the scenario event which is not available for lots of engineering problems. The main goal of this dissertation is to introduce a novel stochastic method for the simulation of the non-stationary earthquake acceleration records compatible enough with... 

In the present study it was intended to evaluate the seismic performance of multi-story EBF structures for designing. When adopting this method, parametric studies are carried out based on the nonlinear performance of such systems whiting the framework of nonlinear static and dynamic analyses. In lines with seismic strengthening of such structures, this study tries to reassess the performance of these systems through increasing ductility and replacing bracing frames with energy damper and special seismic systems. As a result, a fuse type performance is created to protect the other elements of the structure. This study describes the seismic strengthening of this type of dampers using simple... 

Soil liquefaction occurring in loose saturated sand deposits during seismic loadings is one of the most destructive earthquake-induced phenomena in the field of earthquake geotechnical engineering. Catastrophic destructions due to this phenomenon that have been observed in the earthquakes such as Kobe (1995), Chi-Chi (1999), etc. has led to extensive studies in this field. In case of soil slopes prone to liquefaction hazard, detailed analysis of this phenomenon requires considering soil-related factors (e.g. shear strength, relative density, permeability, slope geometry) on the one hand, and earthquake-related characteristics (e.g. amplitude, frequency, duration) on the other. Numerical... 

The purpose of this study is to investigate the resilience of the urban water supply network against earthquakes, A hydraulic analysis of the water supply network was implemented in Rtx software to study the effective parameters in the resilience of the network. Rtx software is a tool for assessing the reliability and resilience of communities and infrastructure to natural hazards by taking into account related uncertainties. The water supply network, like other networks, is affected by earthquakes. The seismic damage varies depending on the vulnerability of the network, the intensity of the earthquake, the focal depth, and the distance from the epicenter. Thus, it reduces the ability of the... 

reparedness and emergency procedure be devised in the event of,and prior to,a disaster. One of these disastersoften accompanying byhuge damages, losses and casualtiesisanearthquake. After such a disaster, several governmental and non-governmental organizations usually start relief operations. They commonly pursue their own agendas and use their own facilities and capabilities to help the people affected without pursuing a central plan. These disintegrated behaviors of involved organizations generate contradictory responses and result in either wasted resources or preventing equitable service for all affected people. Due tothe abovefact, this dissertation proposes amodel for improving... 

Occurrence of natural disasters such as flood, windstorms, tsunamis and earthquakes has caused striking effects on critical infrastructures like power systems in recent decades. There are some examples of high-impact low-possibility (HILP) events which causes catastrophic effects on power systems. Traditionally, planning and operational studies of power system have been run taking into account some reliability metrics. Although, the reliability indices can represent the ability of a system in confronting with possible failures of components, they are unable to efficiently consider the effects of severe events such as earthquake and other HILP events. Moreover, traditional power systems were... 

Elevated water tanks are one of the most critical elements in civilized society to provide safe servicing resources of drinking water after natural and human-made disasters. Dynamic analysis plays a vital role in investigating structural behavior of the elevated storage system subjected to the earthquake-induced vibration. The main scope of this paper is to address the structural stability analysis of the Kish Island’s elevated reinforced concrete water tank employing finite element method. A complete solid model of the structure with detailed design was constructed, and finite element analysis was carried out utilizing ABAQUS software. To investigate the dynamic behavior of the structure, a... 

Shear walls are commonly used in tall concrete buildings to resist lateral loads. Due to the presence of regular door or window openings, a shear wall is often divided into smaller wall units coupled together by coupling beams. In any case, the earthquake resistance of a coupled shear wall structure is highly dependent on the nonlinear behaviour, especially the strength and ductility, of the coupling beams. Many existing building structures without provisions for resisting earthquake loads might no longer be considered to be up to the new standard due to increased-load specifications in the seismic code. A large number of RC coupling beams might require rehabilitation or retrofitting to...