Sharif Digital Repository

The seismic behavior of the non-structural components and their effect on the overall performance of the building structures is among the important issue that should be thoroughly investigated from different aspects such as the resiliency, and the replacing cost. On the other hand, in analysis and design of structures, assuming a rigid under-laying soil is not always right and the effect of soil-structure interaction should be taken into account in certain cases. A flexible support could affect the dynamic characteristics of the structures through elongating their natural vibrating periods as well as increasing their damping ratios, thus should not be ignored. If the period of a... 

Recent studies regarding the damage assessment of structures under severe earthquakes have shown that vertical irregularity of structures have considerable effects on the severity of the induced damages. In these cases, structure enters into its nonlinear behavior, and both structural and nonstructural elements sustain large forces and deformations. In general, nonlinear dynamic procedure (NDP) can provide more realistic results than nonlinear static procedures (NSPs). This is due to consideration of higher modes effects and the shifts in inertial load patterns as the structural system experiences nonlinear behavior. Nowadays, due to the complication of nonlinear dynamic analyses in... 

During the last few decades, the seismic codes have allowed the building structures to behave nonlinearly under the strong ground motions to dissipate the input seismic energy. That usually takes place by formation of plastic hinges in the structural elements which in turn leads to some permanent deformation, such as residual drifts, in these structural members. Repairing these damages are both time and cost consuming. Rocking frames are among the newly introduced re-centering lateral resistance systems which in combination with some dissipating devices (fuse) prevents the formation of plastic hinge in the main frame by concentrating the plastic deformation in these energy dissipating fuse,... 

On Grade steel tanks are widely used in petroleum complexes, refineries, power plants and many urban facilities. Increasing the number of attacks, incident reports and operational events happening in refineries proves the sensitivity of these strategic facilities against various Hazards such as explosion. So, the damage assessment of tanks after the explosion is important for their maintenance and repair.Since some of the tanks containing flammable materials, quick action to estimate the possible damage and required strengthening and retrofitting or disconnecting the input to a plant lifeline is of utmost importance. Therefore, special attention to study the blast loading and the study of... 

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... 

The parallel combination of friction damper with shape memory alloys has been proposed as a self-centering friction damper (SFDB) in the past. The aim of this study is to improve the performance of the SFDB as M-SFDB and investigate its effect on seismic responses of steel moment resisting structures. The basic idea used in the proposed M-SFDB damper is to create sloped surfaces and using SMA bolts to change the slip load of friction during the loading and unloading cycles. In order to evaluate the effect of the proposed mechanism, four types of 4, 8 and 12-story structures located on site classes B and D are designed using ASCE_7-10 and AISC_360-10 codes. These structural models include... 

Tuned Mass Damper (TMD) is one of the most popular device implemented in structures in order to control the motion induced by wind. The performance of TMD has correlation with its design, which is depending on the Structure dynamic properties as well as the specifications of lateral loading. During the earthquake since the both of the mentioned parameters will be uncertain, hence, the reduction of TMD’s sensitivity to its design parameters is vital. In this regard, in 2012, Maurizio De Angelis et al. tested the unconventional TMD – it has a large mass ratio – and corroborated its merit. The results were limited to short structures with linear behavior. This research not only verified... 

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 irregularity in structures is divided into two categories of irregularity in vertical and irregularity in plan. The irregularity in vertical can be caused by ultra-change in dynamic properties of the structure such as mass, stiffness or strength. Research studies indicate that this irregularity leads to intensify the applied damages to structures in severe earthquakes. In general, nonlinear dynamic procedure (NDP) can provide more realistic results than nonlinear static procedures (NSPs). That is due to consideration of higher modes effects and the shifts in inertia load pattern as the structural system experiences nonlinear behavior. Nowadays, due to complexity of nonlinear dynamic... 

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).... 

Project Management has clearly designed to achieve a successful outcome of the projects. However, without a proper practicing, it might convey a different result. Companies are increasingly using organizational project management in their work to achieve company goals. The purpose of this study is to identify the challenges in Iran for successful implementation of directorial patterns based on the PMBoK (Project Management Body of Knowledge) and PRINCE2 (PRojects IN Controlled Environment-2nd Version). This paper presents the results of a study aiming at investigating the impacts of implementing project management processes of PMBOK and PRINCE2 and themes within Iranian construction... 

Progressive collapse occurs when the loading path of a structure is changed so that the other structural elements loaded beyond their capacity and fail. Generally, structural progressive collapse is categorized in different types based on the failure progress mechanism. Most dramatic progressive collapse occurred in 1968 at the Ronan Point residential apartment through an internal gas explosion. The type of progressive collapse of the aforementioned building was the Pancake collapse. Widespread efforts have been put to introduce a simplified static procedure to simulate the removal column phenomenon as in the Pancake collapse, which is a dynamic event involving vibration of building... 

In this research, an investigation on application of parametric low amplitude high frequency vibrations In controlling the seismic response of structures is conducted. Evaluation of the influence of proposed control method on reduction of seismic response of structures, determination of stability map for the proposed structural control system and methods to use this control algorithm in a state needless to monitoring of instantaneous state of system (semiactive control) and a state needful to monitoring of instantaneous state of system (active control), is presented. in beginning chapters, the theory of method by extracting the equation of motion, considering oscillatory term in stiffness... 

With the advent of virtual memory machines and parallel processing, there has been a considerable shift toward computer-aided design and nonlinear analysis of structures. But increasing the size of computer memory or increasing the number of processing units are not the only ways to achieve a satisfactory solution to a large, complex problem. Another useful method is to reduce the size of the problem so that the reduced model is small enough to be solved at an appropriate processing level, and yet the important engineering behavior of the model is preserved in the reduced problem.Reduced models as an alternative, have gained considerable attention throughout the years in order to meet the... 

The circular flexible cylindrical liquid tanks usually are made of steel or aluminum and in majority of cases are built on grade due to its economic advantages. The most important part of a safe design of a storage tanks is the accurate estimation of the seismically induced lateral forces that should be transferred to its base through the tank shell and its support. Seismic behavior of liquid storage tanks is quite different from regular buildings and industrial structures due to its nonlinear behavior caused by complex distribution of hydrodynamic pressure, buckling of its walls, etc.. Moreover, the effect of rocking motion caused by the under laying soft soil, on its response parameters... 

The detuning of the structures equipped with Tuned Mass Dampers (TMDs) caused by their nonlinear behavior under strong ground motions is a real concern in their practical application. This thesis presents a feasibility study on the effectiveness of TMDs in reducing the seismic response and the resulting structural damage of reinforced concrete structures under intense ground motion. A number of 2-D concrete moment resisting frames with different numbers of stories are considered. TMDs are used as a mean to protect these structural models against ground excitation. The mass of TMDs are varied from 1% to 5% of the first effective modal mass of the structural models. IDARC 2-D program is used... 

The considerable structural damage caused by near field earthquakes has revealed the need for further research on their characteristics and their corresponding effects on structures. The short-duration, high- energy pulses present in these types of earthquakes impose high demands on the structures compared to far field ground motions. Thus, more research is needed to improve the current design methods, especially from a performance based point of view for the structures close to faults. This study is about damage assessment of steel moment resisting frame structures under near-field ground motions from a performance based design point of view. A number of 3 and 9-story, 3-D structural model... 

Researches carried out on the damages imparted to the building structures under severe earthquakes have shown the importance of asymmetry effects of the buildings on the level of these damages. In these cases, the structures enter into the nonlinear state of their behavior and the structural elements, as well as nonstructural ones undergo large deformations. Additional damping systems have been proposed in many studies to avoid enforcing such large forces on the structures. One example of these systems is viscous fluid damper. The effectiveness of this type of dampers in reduction of the forces has been shown in many previous works. In this research we look for a damping eccentricity which... 

In the current design Codes, the estimation of maximum inelastic Single Degree Of Freedom (SDOF) displacements is done through simplified procedures by either applying modification factors on maximum SDOF elastic displacement demands or by considering equivalent SDOF systems with elongated fundamental period and increased damping ratio. Thus, the inherent uncertainty caused by approximating maximum inelastic displacements with maximum elastic displacements is neglected. On the other hand, in time history dynamic analysis of structures, the free field recorded ground motions are applied to the base of structures. Obviously, this procedure would be correct when the structure is built on firm... 

Buried pipes are among the most important urban infra-structures which are developed to distribute water, gas, oil, etc.. Researchers have already demonstrated that extreme failures which lead to total disruption of the pipelines, both mains and the distribution network, due to permanent ground displacement in fault zones. In order to avoid any disturbance in the regular performance of pipelines and prevention of environmental contamination, there is a need to investigate the vulnerability of pipelines and their seismic retrofitting, if necessary. In the presented study, the method of pipeline retrofitting by high strength CFRP composite is investigated. In that regard, using a 3D model of...