Sharif Digital Repository

In this study, the behavior of diagonally stiffened steel plate shear wall systems which have a new configuration of stiffeners is investigated. This dissertation is divided into three main sections which contain experimental studies, finite element analysis and developing design equations. In the section on experimental studies, 5 single-bay, single-story, one-third scale specimens were tested. An unstiffened specimen as a control sample and two other specimens with different configuration of stiffeners were constructed and tested to study the effect of diagonal stiffeners. Based on the observations during the tests, it was decided to add and study two other specimens too, including one... 

This research is studying seismic behavior of bridges with spill-through abutments. There is a lot of studies in the literature about the behavior of piers and different types of them in the field of seismic assessment of bridges. But seismic behavior of abutments has paid less attention. In addition, most researches in this field are about common types of abutments like wall-type or integral abutments and also there are few standards and design guidelines about spill-through abutments.However spill-through abutments had been used by designers, especially they are common in Iran.In this research, a bridge with a spill-through abutment is designed as a benchmark. The benchmark bridge is... 

The AASHTO Standard Specification defines diaphragms as a transverse member between girders in order to maintain sectional geometry. Some of the reasons in favor of using a diaphragm are that it prevents the girders from twisting during the process of construction and helps in distributing vertical live loads between girders and transfers lateral loads (wind or earthquake) to supports. It also provides restraint for the lateral-torsional buckling of the girders. While diaphragms at the ends of bridges are called end diaphragms, the diaphragms away from the bridge ends are called intermediate diaphragms. These members are usually made of steel or cast-in-place concrete. Based on their... 

The seismic performance of a low-rise nonductile reinforced concrete (RC) building rehabilitated using eccentric steel bracing is investigated. At first three-story building was Modeled using sap 2000 computer program then analyzed and getting the results. The effectiveness of the eccentric steel bracing in rehabilitating the building was examined. The effect of distributing the steel bracing over the height of the RC frame on the seismic performance of the rehabilitated building was studied. The behavior of the nonductile RC frame members is represented by a beam–column element capable of modeling the strength deterioration and the effect of the axial force on the yield moment and the... 

Smart materials and structures are among the research fields that have been expanded significantly in recent years. At a glance, a smart structure consists of sensors and actuators in which the recorded data are used to control the structural response against the applied lateral loadings, utilizing a specific control algorithm. In this regard, the Piezo-electric materials are widely used both as sensors and actuators in smart structures. In this thesis, the dynamic behavior of a simply supported Euler-Bernoulli beam that beside the effect of moving load or mass is subjected to support excitation is evaluated and the dynamic response of its mid-span is determined. Then, an extensive... 

The purpose of this research is to evaluate skew integral abutment bridges. A bridge with an integral abutment bridge system is a type of bridge in which the expansion joint is removed so the connection between the abutment and the superstructure is rigid. Therefore, the superstructure and the substructure are integrated with each other and both participate in the lateral load of the structure under seismic or thermal forces. One of the important challenges in this type of bridges is the lack of analysis, tests and limited three-dimensional modeling. According to this, the understanding of the behavior of skew integral abutment bridges and the effects of soil-structure interaction in these... 

Due to unusual response of structures of buildings with irregularity in their architecture to dynamic excitations, to have a comprehensive knowledge of their behavior during earthquakes is of utmost importance. Building irregularities are in general divided into two major categories, namely Irregularity in Plane and Irregularity in Elevation, and one of the forms of the latter is where there is a split in the levels of the building. In this work, through a series of case studies, the effects of P- phenomenon on the behavior of steel split-level building structures were studied. 5, 10 and 15 story buildings with 5 and 6 bays, and level splitting of 30, 60, 90, 120 and 150 cm were studied. All... 

With occurring severe earthquakes, damages of columns in RC buildings can lead to overall failure and collapse. So retrofitting of such columns that do not comply with the design requirements is necessary to prevent such phenomena. A variety of methods has been introduced so far for retrofitting. The key factors in determining the retrofitting methods are being economic and easily implemented in the design. Confining concrete columns with pre-stressed steel strips is a new technique that is simple and economic. Previous experimental experiments have shown that this method can enhance ductility and overall seismic behavior of such columns.
In the present study three and six story frames... 

Today using cold-formed steel elements as members of light-weight structures is more common especially in low-rise residential and industrial buildings. Due to Thin-walled plates used to make these sections, members of the frame are prone to premature local buckling and they don’t show good ductility under seismic loadings. Beacause of these reasons, using cold-formed steel elements in moment frames has become a big challenge for scientists. Lots of numerical and experimental models have been presented.
In this study, we investigated the behavior of a beam-column moment connection, consists of two back to back channel sections with curved flanges, using a plate passing through the... 

Concrete filled double-steel-plate (CFDSP) composite wall is a new lateral resisting system that recently used in design and strengthening of high-rise buildings. This CFDSP composite wall is composed of concrete filled steel tubular columns at the two boundaries and concrete filled double-steel-plate wall body. The main advantage of this system is the interaction between steel and concrete which delays local buckling of steel plates. Also, steel jacket increases the strength of concrete in result of confinement effects. Furthermore, these systems have lower thickness compared to ordinary concrete shear walls. Hence, they have less structural weight which reduces the earthquake force.... 

The utilized structural systems in high-rise buildings are under develop in terms of quantity and quality to increase their resistance under gravity and lateral loads. In addition, widespread researches are conducted to introduce and employ modern structural systems for high-rise buildings to improve there behavior in response to the applied forces, and to reduced the levels of hazards imposed by lateral forces. In this regard in recent years, use of diagrid structural systems has gained most of engineers and architects attention. Architectural limitations and improper site conditions may commonly result in construction of buildings with torsional irregularities. However, presence of... 

Use of high-rise structures has become very common in recent decades for different purposes. Since, these structures are vulnerable to the wind and earthquake loads, many ways have been proposed to reduce or dissipate the input wind or seismic energy to the building structures. In this study, the effect of the tuned mass damper (TMD) with high mass ratio for high-rise structures is investigated. The proper functioning of the TMD to limit the vibrations of a structure is depended on the appropriate adjustment of its mass, stiffness and damping characteristics according to the load and structural specifications. The vibrational characteristics of the structures could change during sever... 

In evaluating the damage observed in the structures can be seen that the beam to the wall connection in the walls with openings has severe damage and repair and reconstruction of the beams at the connection is very expensive and difficult. One way to improve seismic behavior and reduce damage in the beams are using steel fibers. Hence in the present study the effect of different fibers in seismic behavior of coupling beams with different length to depth ratio are investigated. The concrete used in the beams of high strength concrete (C60). Therefore, nine model with length to depth ratio of 1.75, 2.25 and 2.75 first without fiber and then with 1.5 and 3 percent made in ABAQUS software. This... 

Buckling-Restrained Braced Frame system (BRBFs) are a new type of steel seismic-load-resisting system that has found use in several countries because of its efficiency and its promise of seismic performance far superior to that of conventional braced frames. The system is addressed in the 2005 edition of the AISC Seismic Provisions for Structural Steel Buildings, also a set of design provisions has been developed by NEHRP. This thesis illustrates the seismic design of buckling-restrained braced frames and compares its seismic performance with the performance of ordinary bracing systems. This work investigates the advantage and disadvantages of this new type of seismic resisting. By having... 

New CKB system is implemented into the multistory frames and investigated how its ductility and energy absorption will be changed if its bracings are able to buckle.buckling braces can improve energy absorption of lateral systems with their post-buckling characteristics through cyclic motions of frames.in proceeding,Nonlinear behavior of multi-story CKB systems within a non-dimensional desigh graphs is presented.application of multi-linear behavior of these systems are controlled by checking their ductility demands and their capacity. Nonlinear dynamic response of multi-story CKB system is analyzed through FEM softwares and presente through curves with which designers can calculate... 

During an earthquake, if the seat width provided at the joint is less than the relative joint opening, the bridge’s superstructure becomes unseat which leads to potential collapse due to the lack of support. Because of the catastrophic consequences of loss of support and the perception that the damage could easily be prevented at relatively low cost, some retrofitting programs focus on preventing such failures involved the addition of longitudinal restrainer cables and bars to limit the relative movements at expansion joints. Noticing the weaknesses of usual restrainers including the transmission of excessive forces to substructures, weak capability of energy dissipation during severe... 

Generally concrete dams have not been sited at location where there were faults classified as active. However, there may be sites suitable for concrete dams where there is some possibility of fault displacement occurring underneath the dam. In addition, there may be situations where an existing dam was constructed over a fault thought to be inactive and later determined to be active, due to different approaches of classification of a fault whether it is active or not. Also some discontinuities may be observed during construction. For these cases nonlinear analysis and criteria will be required to assess the capability of concrete dams to safely withstand fault displacements. In this thesis,...