Sharif Digital Repository

General strategies for seismic design of structure include increasing the rigidity and strength, increasing the energy absorption capacity by implementing energy dissipating devices and reducing the seismic demand by isolating the structure from its base. Isolation system provides the required ductility of the structural system by concentrating its displacements mainly on the isolator level, and separates the structure from the horizontal components of the ground motion. That would create a system whose its main frequency is much lower than the dominant frequency of the earthquake records and the natural frequency of the equivalent fixed-base structure. Because of growing tendency towards... 

General tall buildings consist of different types of structural systems, such as moment resisting frames, with and without shear walls, braces and outriggers. These types of structure have been widely analyzed by many researchers. However, only a few publications are available on the comparison of these structural systems with different stories. In this investigation five types of common structural systems including special moment resisting frame(SMRF), pin structure plus brace, pin structure plus shear wall, SMRF plus brace and SMRF plus shear wall are studied and by doing linear dynamic analysis, a criterion for both lateral displacement and steel tonnage of structures was presented.... 

Dynamic behavior of space structures are of great complexities. On the event of severe earthquake these structures exhibit high resistance and on the other hand, their high rigidity and small deformation makes it necessary to pay attention to their dynamic behavior, especially when combined with other types of structural systems. Also due to lack of sufficient codes and references, their dynamic behavior is still unknown to a great extend. Among these kinds of structures, reinforced concrete double curvature shells, and especially funicular shells, are much more important than others. In this thesis, dynamic response of these kind of structures, especially reinforced concrete domes, in... 

The Steel shear wall is one of resisting lateral load system which has been used since 1970.with respect to design we can apply this system with or without stiffeners .here our investigation is about steel shear wall without stiffeners. Also this system is called SSW. Since using this system is new fashion, there is no specific code for it in Iranian 2800 code .also there is no code for using this system in reinforced concrete frames in any code which makes this investigation much harder. Need to obtain R which is one of the most important seismic parameters, encouraged us to consider R for SSW in 3 to 7 storey structures .we obtained static pushover curves with nonlinear static analysis... 

The Response modification factor R represents the behavior of the structure such as ductility, overstrength and the inherent redundancy. This factor shall be defined according to the type of lateral force resisting system. However, there are some complexities and/or uncertainties in codes related to the R factor according to the height, form of irregularities and structural systems. Therefore, from the scientific point of view as well as reliability, it is very clear that the R factor cannot be similar for all kinds of structures, categorized as a specific group. In this investigation, assuming a low-rise, vertically irregular structure with a heliport which has a dual structural system... 

Airport Traffic Control Towers (ATCTs) are among the most critical structures in an airport that are expected to keep their level of serviceability after severe strong earthquakes. Therefore analysis and design of these structures need a detailed investigation on the seismic behavior of the structure based on the structural characteristics. In this study three different existing reinforced concrete ATCTs have been investigated. As important parameters of earthquake design of structures, response modification factor (R-factor) of these towers will be determined. R-factor reduces elastic force level to design force level and contains the effect of ductility, overstrength. In Iranian seismic... 

The Overstrength, Ductility and the Response Modification Factor (R) for 70 steel X-braced , Inverted-V-Braced and Offcenter Bracing System frames were evaluated by performing pushover analysis of model structure with various stories (3,6,9,12&15 story) and span length (4,6&8 meter). Some result were compared with those from nonlinear dynamic analysis. According to the analysis result the R factors obtained from nonlinear dynamic analysis are 15% more than obtained from pushover analysis and R factors computed from pushover analysis were generally smaller than the values given in the design codes. R factors in Irregular structure in height are about 90% of R values in regular structure in... 

Steel shear wall systems have been introduced as a lateral load resisting system since 1970s. Based on the designer’s choice, this system can be used with or without stiffeners. Employing stiffeners prevents the elastic buckling of steel plates which can enhance the system to absorb more energy. The design code for using stiffners has not developed yet in Iran since this kind of systems is not common practice. In this study, the Response Modification Factor (R), as an important factor in the design procedures of structures, is investigated for 2 to 10-story building structures which have steel shear walls with 3 and 6 millimeters thickness with 3, 4 and 6 meters spans.To this end, the... 

Steel shear wall systems have been introduced as a lateral load resisting system since 1970s. Based on the designer’s choice, this system can be used with or without stiffeners. Employing stiffeners prevents the elastic buckling of steel plates which can enhance the system to absorb more energy. The design code for using stiffeners has not developed yet in Iran since this kind of systems is not common practice. In this study, the Response Modification Factor (R), as an important factor in the design procedures of structures, is investigated for 1,3,5,7 and 10-story regular and irregular building structures which have un-stiffened steel shear walls with 3, 4.5 and 6 millimeters thickness with... 

Tunnel form structures have been proposed in building industry during 40 years for financial saving, suitable structural performance and seismic behavior, and the possibility of performance in an industrial form; and they have also been brought up as one of the innovative technologies of construction in Iran for a couple of years. So far, these structures have been subject to study by the researchers less than frame structures. In comparison to the common structures, evaluating the behavior of these structures is analyzable as two or three-dimensional elements. In this research, the nonlinear behavior of these structures has been simulated and evaluated by using three-dimensional elements;... 

A new eccentrically braced system is discussed. In this system which Named “eccentrically braced frame with vertical link”, the braces is connected to vertical link, instead of floor beam. The vertical link acts as a ductile energy-dissipating element, allowing the rest of the construction such as floor beams, braces and columns remain in the elastic range. In this paper, a parametric study is performed on sample frames with push-over analysis. In these analysis, the efficacy of the variation of link length, link area and the position of the link beam, is studied. The results showed that, the most important effective parameters in improvement of inelastic behavior of frame is decreasing of... 

Let P be a set of points in the plane, each equipped with a directional antenna that can cover a sector of angle and range r. In the symmetric model of communication, two antennas u and v can communicate to each other, if and only if v lies in u’s coverage area and vice versa. In this paper, we introduce the concept of fault-tolerant spanners for directional antennas, which enables us to construct communication networks that retain their connectivity and spanning ratio even if a subset of antennas are removed from the network. We show how to orient the antennas with angle and range r to obtain a k-fault-tolerant spanner for any positive integer k. For ⩾ , we show that the range 13 for the... 

Mount Polley Tailings Storage Facility (MP-TSF) failed on its perimeter embankment on August 4, 2014, when its 9th construction stage has just been completed. The failure releasedmillions of m3 of toxic tailings, supernatant water and construction materials todownstream. Up to this point, some research studies have been conducted into the causes of the failure. These studies have considered the stability of the TSF in different stages of its construction as well as in the last stage. The aim of the present study is to investigate the causes of the very failure, using numerical methods by the aid of the finite element based software, PLAXIS 2D. In the present study, the results of the... 

In the present study, a number of Steel Plate Shear wall (SPSW) models with various infill plates such as perforated and slit infill panels are analyzed and the results are utilized to discuss about behavior of Steel Plate Shear walls with various infill plates. The ABAQUS finite element package is utilized for all Eigen value and incremental nonlinear pushover analyses. Cyclic loading is in compliance with the ATC 24 loading protocol (ATC 1992). To validate modeling, boundary conditions and loading procedures, the experimental results provided by Darren Vian et al. [102, 103] and In-Rak et al. [48, 49] was modeled and analyzed. Investigation of steel plate shear walls made of different... 

On the ground, it is necessary to have the values of Response Modification Factor R, Over-strength Factor Ω0, and Deflection Amplification Factor Cd to design seismic-force-resisting systems according to design and loading codes. This study is intended to evaluate these factors for a structural lateral bracing system called Chevron Knee Bracing (CKB). In this type of bracing, the knee elements help the system to dissipate energy through the formation of plastic flexural and/or shear hinges within the presented bracing system. The ap- proach used in this study is according to FEMA P695 based on low probabili- ty of structural collapse and involves nonlinear static and dynamic analyses.... 

The subject of this research is design of passive control systems for nonlinear structures using active control algorithms and modification of structural stiffness, strength and damping. All the systems considered are the categorized as the shear-type buildings. Furthermore, pole assignment and sliding mode algorithms are used as the proposed algorithms. The method used here to reduce the response of the system (the word “response” is referred to the absolute acceleration and inter-story of stories) to the optimum or desired values, implements the stiffness and strength reduction and increasing the damping. Reduction of stiffness and strength are used to prevent damaging non-structural and... 

Nowadays, the knee bracing system (KBF) takes civil engineer’s attention because of its benefits and properties. This new form of framing is constructed through the knee and the diagonal brace elements. The knee part is a fuse-like component that dissipates energy by the formation of plastic flexural and/or shear hinge, when the building is subjected to severe lateral loads. In this system, the diagonal brace provides most of the lateral stiffness. Also the flexural or shear yielding of the knee element provides the ductility under a severe earthquake. In this way, the damage is concentrated in a secondary member, which can be easily repaired at minimum cost. Floor distortions are reduced... 

Usually the structures are designed based on the fixed-base assumption; however this assumption is not always correct and the bed flexibility should be considered. This effect which is called soil-structure interaction, change the response of structure on both elastic and inelastic behavior. In the regulations for the design of structures on flexible base, generallysoil-structure system is replaced with an equivalent fixed base structure; in the way that the design force of soil-structure system with reasonable accuracy can be estimated by equivalent fixed-base structure. In some regulations, dynamic characteristics of equivalent structure have been determined on elastic state and the... 

A generic single-span frame has been used to represent a shear-flexural building and the degree of participation of overall shear and flexural behavior in mode shapes, is controlled by dimensionless parameters of α, δk and δp. By evaluation of modal analysis results, one may conclude the extent to which each parameter affects the dominancy of shear/flexural behavior. By understanding the relation between the abovementioned parameters and proportion of shear/flexural behavior of structures, effects of these parameters and consequently trend of modal shapes on the nonlinear analyses results would be investigated. According to nonlinear analyses results of the flexural structures, ductility...