Sharif Digital Repository

Various types of passive energy dissipating systems have been introduced for controlling the seismic response of structures during the last few decades. A number of these control devices have been practically implemented in different structures all over the world. Shape Memory Alloy (SMA) is among those passive control systems that have attracted a large attention due to its innate features, i.e., recovering the induced residual strains upon unloading (superelastic effect) or by heating (shape memory effect).This study investigates the seismic behavior of a set of steel structural models with different number of stories and eccentricities equipped with a type of fixed SMA connections. In the... 

Application of Shape Memory Alloys (SMAs) as a means for vibration suppression of structural systems has extensively been explored in recent years. Recovering the applied residual strain upon unloading (super-elasticity) or by heating (shape memory effect) at different temperature ranges are two inherent features of SMA materials that have gained most attention. In this work, the seismic behavior of a proposed beam-column semi-rigid end-plate connection that has been equipped with both steel and SMA studs in austenite phase is investigated. A number of 3-D steel MRF structural models with 6,9 and 12 number of stories are considered. These structural models are subjected to bi-directional... 

In new method of performance-based design, the behavior of structure during earthquake is considered more realistically, and applying damage parameters like plastic ductility and inter-story drift to determine the seismic performance of structures is suggested. Damage indexes, the contribution of damage parameters to damage capacity of structural members, are defined to specify damage level of each element. In addition, damage spectrum which is the diagram of values of certain damage index versus natural period of single-degree-of-freedom system will be useful to seismic assessment of existing structures and seismic design of new ones. By the way, endurance time (ET) method can be... 

In Endurance Time method structures are subjected a set of predesigned intensifying excitations. These excitations are produced in a way that their response spectrum, while complying with a specified spectrum, intensifies with time. So they can be used approximately to simulate the average effects of several ground motions scaled to different intensities. In this study applicability of Endurance Time method for evaluating collapse potential of buildings is investigated. A set of steel moment frames is used for collapse assessment. The process of using Endurance Time method in collapse evaluation is explained with consideration of uncertainty effects. collapse fragility curves and collapse... 

This study evaluated post-tensioned system’s behavior in the steel structure. The post-tensioned system includes post-tensioned frame and gravity system (gravity frame and floor diaphragm) and considers the interaction of post-tensioned frame with gravity frame. Post-tensioned frame is the moment frame that has post-tensioned connections instead of ordinary connections. Bolted top and seat angles are used in the connection, along with post-tensioned high strength strands that run parallel to the beam. The strands compress the beam flanges against the column flange to develop a resisting moment and the friction between the beam and column and the two angles resist shear. Studies showed that... 

With increasing population and lack of habitable spaces, the building heights increased in cities around the world. Placing components of a structure in tandem may cause a permanent failure of the members due to strength reduction. During recent years, this kind of failure occurred in different places of the world, and is called progressive collapse. There are some various samples of the progressive collapse which all are good samples of failures such as building failure in Ronan Point in the UK, Twin Towers or the world trade center in NY, and Pentagon building. According to these issues, different institutions codified guidelines and codes in this field such as Department of Defense as DoD... 

It is very common to use moment frame system in earthquake-prone areas in the two main directions of buildings. This system is very popular among architects due to the creation of unobstructed openings between the columns and the possibility of using openings in them.The column is one of the main components in the design of orthogonal moment frame systems and plays an important role in the performance of this system. The columns that are in the two main directions of the intersection of two moment frame systems, due to the existence of the 30-100 rule in seismic design regulations, must be able to withstand 100% of the design earthquake force in one direction and 30% of the same force in the... 

In order to reduce structural and nonstructural damages and associated financial losses during intense seismic events such as Bam earthquake, seismic retrofitting of existing structures should be considered as a special issue. In this regard, for quantifying the seismic performance of structures a guideline termed “instruction for seismic rehabilitation of existing building No.360” is issued which is mainly borrowed from performance-based assessment procedures FEMA 356. In contrast to conventional seismic design methods which are based on controlling stress ratio for different load combinations, in performance-based earthquake engineering methodology, the displacement control of structural... 

Composite Reinforced Concrete-Steel (RCS) frames which have reinforced concrete columns and steel beams attracted a lot of attention in recent years. They take advantage from the benefits of both reinforced concrete and steel frames thorough using the optimum combination of concrete and steel structural elements. In this research six structures including three 3-story, and three 6-story buildings are designed in a region with very high seismicity risk. These structures include composite RCS moment frames, special steel moment frames, and reinforced concrete special moment frames. RCS moment frames which are designed they not only have reinforced concrete columns similar to reinforced... 

Recent research in the field of earthquake engineering has seen the development of a number of different displacement-based seismic design (DBD) methods. Such methods aim to overcome limitations with the force-based design methods incorporated in current codes, and the most developed DBD method currently available is the Direct DBD approach, presented by Priestley. The objective of this work is to investigate the performance of the Direct DBD design procedure for steel moment-resisting frame structures. For this purpose, a series of regular steel MRF frames, varying from 4 to 20 stories in height are designed based on DDBD approach and utilizing displacement design spectrum of the Iranian... 

For many years of tall buildings with regard to the development and progress towns are necessary for the urbanite of the city and are considered as progress of the symbols societies. These buildings because of high wore their features special treatment under the influence lateral loads like the earthquake. In a way that today is an important issue in seismology and Earthquake Engineering all the powerful movements of the earth and its effect on the performance of the workforce special buildings as tall. Two points in this important subject. First modeling and simulations of the Most Powerful Earthquakes that in general occur in the field of near source earthquake generator. The earthquake of... 

Considering connections as ideally rigid or pinned is a common assumption during design and analysis of steel moment frames. However, in real world, steel connections show a non-linear behavior between these two ideal states. The aim of this research is to investigate the effect of partially restrained connections on the design and performance of two-dimensional steel moment frames under vertical and horizontal loads that are applied statically. For this aim, nonlinear finite element modeling is used in probabilistic evaluation process to assess the performance of existing structures. To capture the real behavior of structure in models, geometric and material sources of nonlinearity are...