Sharif Digital Repository

Bridges are among the crucial elements of transportation networks and play an important role in facilitating emergency relief efforts following earthquakes. For this reasons, they should have an appropriate performance in earthquakes; Thus, presentation of true design of bridges was necessary. Elastic design of bridges due to the earthquake is uneconomic; hence, during an earthquake, the codes permitted to structures go to their inelastic behavior domain but inelastic analysis of structures are noncommercial and the capability of detail modeling of the inelastic behavior of the material is still impossible. Therefore, designers use response modification factor to consider the inelastic... 

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... 

The purpose of this study is to investigate the seismic performance factors of a structure with the composite shear wall system that, if properly implemented, a nonlinear seismic design process will lead to safety against earthquake collapse. In this research, a special type of composite shear wall is investigated, which consists of a steel plate in the middle of the reinforced concrete shear wall. The purpose of this combination is to improve the performance of the wall because steel plates can effectively improve the seismic behavior of the structure, and concrete can protect the steel plate from buckling and corrosion. In this study, numerical models are validated according to previous... 

In this thesis behavior of intermediate steel moment frames and intermediate steel moment frames equipped with knee element are investigated. The knee element attaches to the beam element by inverted-V type concentric braces. The knee element acts as a fuse to dissipate input energy during an earthquake by the formation of plastic hinges. On the other hand, brace elements remain in the elastic range without buckling and provide suitable lateral stiffness. Main object of this investigation is reducing deteriorations in the main frame in intermediate and sever earthquake by concentrating deteriorations in knee element. Whereas knee element is not a main element of the frame, retrofitting of the... 

Integral abutment bridges (IABs) are bridges in which the deck is cast monolithically with abutment backwalls. These bridges are also jointless through deck length, due to which they act as a frame in their longitudinal direction. These differences with common seat-type bridge construction, have made IABs more economical to build and maintain and superior in seismic performance. As such, in various countries, this method of construction have been prescribed whenever possible. As an instance, integral construction is mandatory for bridges up to 60 meters in total length in England. IABs have become more of a geotechnical problem rather than simple structural problem of conventional bridges in... 

In this study, seismic performance of steel diagrid structures is investigated using far-field earthquake records and their seismic performance factors, such as overstrength factor (Ω_0), ductility ratio (µ_T) and response modification coefficient (R) are evaluated according to the FEMA P695. To meet this objective, 12 archetype 3-D models of diagrid structure with two different height of 8 and 12 stories and three different diagonal angles of 45, 63.4 and 71.5 degrees are designed according to the ASCE 7-10 and using response modification factor R=3.6. With regard to the main horizontal beam connections with the diagrid system, equal number of models with pin and rigid type of connections... 

Purpose of this research is evaluation of response modification factor for integral abutment bridges in longitudinal direction in which substructure and superstructure both act as a unit system in resisting of lateral loads and no expansion joints are used in them. One of the most important challenges in design of IABs, is lack of response modification factor for their seismic design in longitudinal direction. Another challenge in these bridges, is modeling of soil-bridge structure interaction that affects not only abutment and piles’ seismic performance, but deck performance too. The other challenge is lack of adequate knowledge about their behavior and seismic performance which is of great... 

Tension-Only Concentrically Braced Frame (TOCBF) incorporates very slender bracing members, such as single angles, that are unable to dissipate much energy in compression due to their negligible buckling strength. Alternating tension yielding and elastic compression buckling of the bracing elements result in rapid strength degradation during strong motions, which translates into deteriorating pinched hysteresis loops. Based on this unfavorable behavior, it is not recommended to employ TOCBF system for medium and high-rise buildings located in active seismic areas. However, as a result of its inexpensivity and simplicity to design, the TOCBF system is used prevalently in low-rise steel... 

Steel structure with saddle connections constitutes a portion of the old steel structures in Iran. During past strong ground motions such as Manjil and Bam earthquakes, these structures were vulnerable and experienced significant damages. These structures were widely used due to their easy installation. However, according to their unpromising behavior, they need an appropriate lateral force-resisting system. A concrete shear wall is one of the suitable lateral force resisting systems that can improve the behavior of steel frames with saddle connections. To find the coefficients of seismic performance factors including response modification factor, overstrength factor, and deflection... 

This investigation is intended to assess the behavior of SCBFs in the presence of typical brace members, which buckles in compression, and BRBs joining by yielding elements. While braces play a role in providing stiffness for structure, central yielding elements will act as energy-absorbing fuses. In this frame type, energy dissipation will mainly be undertaken by BRBs and yielding elements. The mentioned yielding elements do this by initiating plastic hinges in each corner of the central frame. As it is clear, designing a structure that includes the stated lateral-load-resisting system necessitates seismic performance parameters to be evaluated. Hence, by pursuing the FEMA P695 methodology,... 

This study aims to assess and compare the seismic performance of moment frame and dual reinforced concrete systems at different ductilities and seismicity levels. Seismic performance of the systems is defined as their efficiency in providing safety and reducing the life-cycle as well as the total cost of the buildings. For this purpose, 30 archetypes were designed in accordance with common Iranian codes, and their response at different seismic intensities was obtained by Endurance Time method. Afterward, the consequences of earthquakes were estimated according to FEMA-P58 guidelines, and the total cost of the buildings was determined. All of these archetypes had residential occupancy but... 

Vertical addition of existing buildings provides more living space without the need for more land use. Also adding a story on an existing building is one of the common needs in metropolitans. However, the structure may bear high risk due to vertical addition. This study aims to model conventional concrete structures built in Tehran and then assess and compare the seismic performance of base structure and extended structure. Seismic performance of a system is defined as their efficiency in providing enough safety and reducing the Life-Cycle Cost. For this purpose, seven archetypes as base structures and eight extended structures corresponding to base structures, that had residential...