Sharif Digital Repository

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... 

Structural response to near fault ground motions has received significant attention in recent years. Such ground motions are different from ordinary ones and are characterized by a large, long period, velocity pulse caused by the forward directivity. These velocity pulses could potentially impose sever demands on structures and increase their risk of seismic collapse. The situation could even be worse for tall buildings with fundamental periods close to the period of the velocity pulses, and requires special consideration in design process. Prediction of seismic-induced collapse potential of structures has been among the main concerns in Performance Based Earthquake Engineering (PBEE). The... 

Nowadays, the design of new structures and the renovation of existing buildings against earthquakes using energy absorption systems are very common. On the other hand, the near-field earthquake are characterized by directivity related velocity pulses with large accelerations. Recent studies have shown that the performance of the passive energy dissipation mechanisms are significantly depended on the characteristics of the near field velocity pulses. The efficiency of various passive dampers in damage mitigation of different building structures have been carefully evaluated under near field and far field earthquake records. In this study, the ability of viscoelastic dampers in controlling the... 

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... 

Assessment of the probability of collapse or exceeding other limit states is one of the major goals of Performance-Based Earthquake Engineering. Moreover, other beneficial materials such as estimation of loss of money and downtime, which make it convenient for decision makers to judge the condition of a structure and take wise steps about it, can be drawn from the results of such an assessment.Current work investigates the probability of collapse and also immediate occupancy limit states at three discrete hazard levels of 50%, 10% and 2% in 50 years and also by utilizing mean annual frequency approach for three archetypes of steel special moment-resisting frames of 4, 8 and 12 stories.Ten... 

Earthquakes cause considerable damages and human and financial losses all around the world. Without doubt, the most important earthquake injuries are those that arise as a result of building failure in an earthquake. Conventional design codes provided a minimum level of protection against strong ground shaking to mitigate earthquake effects on structure by utilizing structural elements such as shear walls, braced frames, etc. Although, these provisions guarantee only that the building will not collapse, but it does not protect the buildings from structural damage. This method considers strengthening of structural lateral resistance system to verify earthquake forces. However, new methods... 

Reinforced concrete slabs carry both vertical gravity loads and in plane forces due to seismic loads. In this study interaction of bending and in plane forces will be considered. Lee et al. in 2007 studied the floor diaphragm behavior. They considered combination of both in plane and out of plane loadings. In the most previous studies, the diaphragm behavior of a floor slab was represented by its behavior under in-plane forces only. With this assumption, analysis of the floor diaphragm was simplified to the two dimensional plane stress problem. For low-rise buildings, the lateral stiffness of the structure is usually higher than high-rise buildings.Tena et al. in 2014 assessed ment the... 

The main goal of partake quake-attenuating in buildings is to absorb energy and to attenuate the exerted forces into structures as a result of ground motions. Notwithstanding achievements and developments in the field of dampers production, applying of dampers in structures is proportional to following complicated technology and subtle engineering. Installation and initiation of dampers depend on educated and expert crew; moreover, such attenuating systems need maintenance and repair during the useful structural life time. Therefore, nowadays civil engineering suffers from the lack of such quake-attenuating systems to be able to respond simply but applicable mechanism at the same time for... 

In this research, a single degree of freedom (SDOF) system equipped with a telescopic damper is analyzed under earthquake excitations. In order to assess the effectiveness of telescopic damper, some SDOF systems equipped with other types of dampers including viscous damper, friction damper, T-ADAS damper, and Curadelli’s lead damper(CLD) are also analyzed under similar excitations. Inspired by CLD damper, this TLSD damper is primarily introduced, developed and tested at Sharif University of Technology in Tehran by Mr. Pournamazian in 2016. Results shows that the telescopic lead shear damper can increase the CLD damper displacement by 100%. To get better results in terms of damper’s behavior... 

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... 

The parametric study of a new introduced metallic yielding damper called telescopic damper is addressed. The telescopic damper comprises of three concentric steel pipes connected together by lead shear keys. The inner and outer steel pipes are subjected to axial loading which results in the shear yielding of the embedded lead cylinders. The inner steel pipe has a lock which limits its movement to some certain extent and beyond this limit the outer tube activates. Employing ABAQUS software, the behavior of damper under cyclic loading is studied numerically. The finite element model is verified by available results in the literature. The effects of inner and outer steel pipes thickness,... 

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... 

Base isolation system is an efficient passive structural control approach to save the structures from the harms of earthquakes. The base isolated systems help to reduce the base shear by increasing the period of the structures, as well as dissipating the seismic input energy by its inherent damping mechanism [1]. However, the residual displacement of the base isolation systems resulted from strong ground motions would remain as a main obstacle in its regular serviceability after the main event. In that regard different isolating devices have been introduced to resolve the problem of the remaining permanent displacement. On the other hand, Shape Memory Alloys (SMAs) are among the newly... 

In this study, a new type of metallic yielding damper called Telescopic damper is proposed and analyzed numerically. The damper comprises of three concentric steel tubes connected together by lead shear keys. The relative axial deformation of steel tubes under axial forces results in shear deformation and yielding in lead shear keys and dissipates energy. The inner steel tube has a lock which limits its movement to some certain extent and beyond this limit the outer tube activates. Therefore, a multi-linear force-deformation behavior with two different yield plateaus is expected for the introduced telescopic damper. The multi-level yield plateaus of damper makes it effective in both low and... 

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... 

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  

The pervious Iranian seismic code has not considered the ductility parameter in the seismic design of (steel) structures. , therefore; seismic vulnerability and retrofit of existing steel structures is becoming a vital engineering problem. Common ways of seismic retrofit such as adding a shear wall or bracing the structure cause huge forces in elements and foundations. Rehabilitation on the foundation has many constructional problems and leads to long down time. As far as known, the Infill Walls increase the lateral stiffness of frames and lead to reducing the period of the structure. Therefore, to have a reliable design, it is important to consider the effects of Infill Walls. It can be... 

The majority of modern seismic Codes and guidelines require scaling of selected ground motion time histories so that the dynamic time history analyses results will be comparable to those obtained from the dynamic modal analyses. The scaling procedure would basically apply, considering a specific part of the design spectrum depending on the approximate period of the system. In this work, the efficiency of the proposed scaling method of earthquake records by ASCE STANDARD 7-10 for evaluation of true response parameters of base isolated structures will be investigated. For this purpose, a number of 3-D structural models with different numbers of stories will be considered. Then, using... 

The objective of this study is to evaluate the seismic vulnerability of the existing buildings subjected to the near field earthquakes. The main applications of this research are loss estimation and performance evaluation of the existing buildings. That could provide a better solution and particularly more useful information to the owners, investors, and insurers about the expected performance of buildings under earthquake excitations. A number of 2, 5 and 8 story reinforced concrete buildings, designed according to the old Iranian seismic provisions of ISIRI-519 and ACI 318-83 codes for the ordinary moment resisting frames, are considered. By the use of a number of near field earthquake... 

In recent years there has been a huge amount of attention in the application of the base isolation system as a passive procedure to limit seismic response of structures. A number of international codes including UBC97, ASCE07-2005, and ASCE-2010 have devoted a special part for the Seismic analysis and design of base-isolated structures. The present work investigates the vertical distribution of the lateral seismic force, for base-isolated structures suggested by the ASCE07_05 code under near field earthquakes. Near field earthquakes have attracted so much interest among the researchers and engineers due to their disastrous effects on structures. According to the recorded data, it is...