Sharif Digital Repository

The AISC Seismic Design Provisions now include capacity design requirements for steel plate shear walls,which consist of thin web plates that infill frames of steel beams, denoted horizontal boundary elements)HBEs), and columns, denoted vertical boundary elements (VBEs). The thin unstiffened web plates are expected to buckle in shear at low load levels and develop tension field action, providing ductility and energy dissipation through tension yielding of the web plate. HBEs are designed for stiffness and strength requirements and are expected to anchor the tension field formation in the web plates. VBEs are designed for yielding of web plates and plastic hinge formation at the ends of the... 

Problems with composite materials can indicate the lack of mechanical properties of the layers, especially in high temperature, which led to the expansion of functionally graded materials. The most important application of these materials is in high temperature environments .therefore the study of their behavior under mechanical and thermal loads in the range of small and large deformations is very important.The purpose of this research is to provide an analytical solution for nonlinear behavior of functionally graded circular sector plates under thermomechanical load.The material properties are graded through the plate thickness according to a power-law distribution of the volume fraction... 

In the recent years, neural networks have been used to solve many problems in different fields, specifically in engineering problems. Neural networks have different applications in material science and structures including modeling stress-strain relationship of composite materials and static and dynamic analysis of structures. Recently, a new method called neuro-finite element has been developed for nonlinear static analysis of structures manufactured by one-dimensional elements. In this method, by investigating the load-deflection diagram of each element, it is possible to analyze and produce a load-deflection diagram for the whole structure using neural networks. This experimental study... 

By constraining the steel members against lateral buckling, buckling-restrained braces (BRB’s) show similar load-deformation behaviors and energy absorption capacities in both tension and compression. As a result, BRB’s demonstrate significant energy dissipation capacity compared to ordinary braces. On the other hand, the relatively small post-yield stiffness of BRB’s usually leads to significant residual drifts, which may render the structure unusable. In recent decades, significant research has been put into improving the performance of structures equipped with BRB’s. In this project, the current methods to enhance the performance of the BRB’s are explored, and novel approaches are... 

This study proposes a robust technique for large displacement analysis of slack cable structures subjected to dynamic loadings using a novel method, entitled Node Relaxation. Ordinary numerical methods are usually unable to analyze cable structures due to singularities arising from large displacements and rotations following any alteration of the applied loads. When dynamic loads are considered, handling these singularities in numerical analyses becomes even more challenging. In this thesis, an effective iterative method is proposed for three-dimensional large-displacement dynamic analysis of structures consisting slack cables as the primary load-bearing system. The cable structure is... 

This research studies behavior and implementing of telescopic lead shear damper in structures. Telescopic lead shear damper (TLSD) is a type of metallic yielding dampers that can dissipated energy with usage of shear yielding of lead. TLSD is made from behind act of two lead shear damper (LSD) like a telescope. Lead shear damper composed of two coaxial steel pipes where their interfacial gap is filled with pure lead. The interface of lead and steel pipes are roughened in a threaded form to guarantee the no-slip condition across the interface. Due to stable and fat force displacement hysteresis loops of TLSD, this device can be used in structures subjected to wind, seismic, and other dynamic... 

Iran plateau is situated over the Alpide-Himalaya earthquake belt. Tectonic studies indicate that this plateau has a very high density of active and recent faults; as a result, Iran is at risk of damaging earthquakes. Experience of past severe earthquakes shows previous designed structures do not have enough strength instead of real earthquake forces, therefore vulnerability study of existing structures and give a technical and economical retrofitting plan of them is required. Conventional methods of seismic rehabilitation for example using concrete shear walls or steel braces are not suitable for some buildings. Nowadays, passive control systems have been successfully used for reducing the... 

Research on the characteristics of the near field earthquakes has been very popular in recent years due to the considerable damages they have caused to the structures located within the vicinity of seismic sources. The incapability of response spectra for structural damage assessment has been revealed through recent investigations. The recorded data show that the near field earthquakes are often accompanied by a large energy pulse in the beginning of the records caused by the so-called directivity phenomenon. That has encouraged many researchers to study the possibility of using the velocity pulse of these records to evaluate the imposed seismic demands on structures. Thus, investigating the... 

This research introduces two new passive control devices for protecting structures against earthquakes: Dual Pipe Damper (DPD) and In-filled Pipe Damper (IPD). The DPD device consists of two welded pipes. The IPD device is a DPD with two smaller pipes inside them and the spaces between the pipes are filled with metals such as, lead and zinc. The DPD device only utilizes plastic deformation of pipes; but the IPD device takes advantage of plastification of the outer and inner pipes, the in-filled metals, and the friction between metals as energy absorption mechanisms. Quasi-static cyclic tests are performed on four specimens of DPD and six specimens of IPD all showing stable hysteresis and... 

This study aims for investigating a novel type of Steel Plate Shear Wall (SPSW) system in which the plate to boundary column connections are eliminated and the plate is reinforced with side, horizontal or cross stiffeners. SPSWs are one of the best lateral load resisting systems specially in high-rise buildings which makes it to be widely used in modern construction projects. SPSW system was first used in Japan and United States and found its way to other countries through the next years. In contrary to United States, stiffened SPSWs are more popular in Japan as it is a high seismic area. Despite the numerous advantages of this system, the main drawback of SPSWs is the large column sections... 

Modeling is one of the most important steps in analysis and design of structures. Most of the time behavior of floor diaphragms is assumed completely rigid in their plane in order to simplicity in practical design. Although this assumption leads to acceptable results in analysis and design of conventional buildings, erroneous results may assess in some particular buildings—for instance narrow buildings with stiff end walls. Accordingly, behavior of these buildings in future earthquakes opposes those were predicted in design phase, and they are so vulnerable since in-plane deflection of floor diaphragms are striking which cannot be ignored. This thesis investigates the significance of... 

Composite systems consisting of concrete columns and steel beams are introduces as structural systems in recent years. These structural systems enjoy merits of both steel and concrete frames by efficiently combining the advantages of them. This study is allocated to lateral force resistance system using armed concrete and structural steel. Advantages of composite structures rather to those of two other conventional ones are among performance characteristics under ultimate loads, economical conservation, and higher speed of construction.In this research the aim is to study these frame under earthquake induced loads. The seismic performances of these composite frames with through column beams,... 

The purpose of this research is to provide an analytical solution using first order shear deformation theory for nonlinear bending of rectangular FG plate under mechanical and thermal loads with different boundary conditions. To achieve this goal, extended Kantorovich method have been used. This method has a high convergence rate and is more accurate than other approximate methods, such as the Ritz and Galerkin methods, because the partially differential equations are converted to ordinary differential equations. In order to solving nonlinear odes the perturbation method is used. Material of the plate is a mixture of ceramic and metal and is modeled as an isotropic and non-homogeneous... 

Today, with the replacement of the old method of force-based design by the new method of performance-based design in structural and earthquake engineering, many structural and earthquake researchers have focused in their studies on this area. The performance-based design aims at enabling engineers to design structures with predictable performance. Designing space structures has particular complexities. In space structures, the failure of a structural member does not necessarily mean the failure of the entire structure, because the redistribution of power will occur between the adjacent members after the failure of a member and the structure can thus have further support capacity. Similarly,... 

Explosion as a physical phenomenon have various effects on the environment, including living organisms, surrounding buildings, equipment and infrastructure there. Due to such extreme loading conditions, efforts have been made during the past three decades to develop methods of structural analysis and design to resist blast loads. The analysis and design of structures subjected to blast loads require a detailed understanding of blast phenomena and the dynamic response of various structural elements. The most appropriate method for evaluating the behavior of structures under blast loading is performance approach which specifies the response of structures against explosion. It seems that... 

Today, many evidences, including the distribution of galactic velocities, gravitational lensing observations, and the cosmic microwave background, show that there exist dark matter (non-baryon matter) in large-scale cosmological structures that are stable, free of charge and without color, which has gravitational interaction like normal matter. The hypothesis that weakly interacting massive particles (WIMPs) as a dark matter candidate with mass range of several tens of GeV to several teV and with the typical couplings of Electroweak order of magnitude, is an attractive and desirable model, Which naturally explains the density of cosmic dark matter in agreement with observations. Alongside... 

Steel bracing systems can be used effectively for seismic retrofitting of existing RC buildings as well as for seismic design of new building. Steel bracing system has been used to increase the lateral load resistance of steel structures. In recent years the concept of steel bracing has also been applied to the retrofitting of reinforced concrete frames, especially to improve seismic performance of non-ductile reinforced concrete buildings. The use of steel bracing systems for seismic rehabilitation of RC frames offers some advantages such as (a) minimal added weight to the structure; (b) ease and speed of construction;(c) increased architectural flexibility; in comparison with RC shear... 

Endurance Time (ET) method is a relatively general analysis method based on time history analysis for evaluation of structure systems under dynamic excitations resulted from earthquakes. Assessment criterion in this method is based on time of endurance of structure versus applied acceleration function and don't use parameters such as stiffness, lateral strength, period of structure and other dynamic characteristics straightly. Upper time of endurance means better operation. In this method, if assumed damage index stays under allowable limit until determined time of endurance then the structure assumed acceptable. In this study, nonlinear analysis of anchored and unanchored (on rigid base)... 

Seismic isolation is well known as an effective and applicable technique to protect structures from destructive ground motions. Considerable functional and economical advantages of this technique have led to application of isolation systems at upper levels. In this study, seismic responses of a 6-story structure with a constant fundamental period, which is seismically isolated at the base and mid-height by non-linear isolation systems with variable nominal periods, are investigated. Analytical results indicate that stories below mid-height isolator show large changes in seismic responses caused by changes in isolator nominal period in comparison with upper stories. Although the fundamental... 

Wall-Frame interaction under lateral load has been considered in studies, and it is concluded that interaction lateral forces of rigid frame and shear wall varies at different stories. This is resulted from of different mode shape of rigid frame and shear wall under lateral loads which are shear and bending mode, respectively. However most codes recommend a minimum strength for frame, equal to 25% of total lateral force, as an acceptance criterion of shear wall-frame dual action; otherwise this minimum strength does not fully comply with horizontal distribution of lateral load according to relative stiffness of components.The purpose of this article is to study nonlinear seismic response of...