Protective systems constitute the most vital defensive element of power networks against unusual conditions. Therefore, any malfunction caused by cyber-attacks may cause huge consequences for power networks such as widespread blackouts. Among the most critical protective systems vulnerable to cyber intrusions are generator protection, transmission lines, and transformers. Cyber sabotages can be mitigated through strategic proceedings to reduce their impact on the network. This paper provides a comprehensive review of the methods of strengthening the protection system against cyber-attacks, given the importance of power network protection systems. For this purpose, in the first step, protection-based methods for strengthening the power network against cyber-attacks are presented. Then, in the second step, detection-based methods are described to reveal a possible cyber-attack. Since there is no definite guarantee against cyber intrusions, it is possible to prevent the progress of the attack by using attack detection methods. To this end, two types of data-based and model-based algorithms are utilized. In data-based algorithms, network knowledge and information can be optimally used to detect the conditions of cyber-attack compared to the conditions without cyber-attack. In model-based algorithms, parameters of the network are estimated by executing state estimation algorithms based on system relations. Then, data manipulation and cyber intrusions are detected despite the discrepancy between the estimated values and the measured values. Consequently, the use of defense and detection methods to deal with cyber intrusion leads to an increase in the cyber security of the power grid protection system. In this regard, it is very important to use various defense and detection algorithms in combating cyber-attacks.

With the knowledge of constant threat of major earthquakes and especially the latest dramatic and catastrophic earthquake of northern Iran in 1990 and recent quakes of 1997,a multi-disciplinary program was launched in Iran to assess seismic vulnerability of important buildings and possibly offer cost-effective strengthening solutions for the ones in need. As a result of the latest awakening toward upgrading the existing buildings in the country, especially capital city of Tehran, this paper will concentrate on the upgrade design of a ten story steel framed hospital for both vertical and lateral loads, providing information on the strengthening procedures and considerations used to achieve the goals of the project. The existing structure under investigation is a ten story steel framed skeleton with four story completed and under use, constructed to old seismic code in 1985 and left alone due to economical reasons until 1997 the beginning of this project. Four different schemes were considered for this particular building which will be discussed herein with main considerations being economical and easy construction. Static equivalent procedure was utilized in the design of the upgrade system and then, behavior and design was controlled using non-linear dynamic analysis utilizing DRAIN-2D program. Details of this project will be discussed in this paper.

The target of seismic improvement of a building is to strengthen the structural and non-structural members in order to reduce the earthquake damage.Dampers dissipate the structure’s energy. By using these types of equipment, the damage to the structure is dramatically reduced. In this article steel frames with three, six and ten stories with and without dampers are modeled in SAP software. They are evaluated by using seismic retrofitting guidelines and nonlinear static method. The results show that adding a viscous damper reduces seismic effect and damage performance level. In addition, using dampers in high-rise structures is more effective than shorter ones in reducing the effects of an earthquake.

Khorjini (saddle) frame is one of typical structural systems in Iran and needs seismic retrofit based on previous research reports. In this paper, a sort of hysteresis dampers called buckling restrained braces (BRB) is considered and its behavior and design procedure are investigated to study its effect on seismic performance of steel frames. Finally, a typical khorjini (saddle) frame has been seismically retrofitted and was analytically subjected to the time-histories of the Naghan, Tabas and Northridge earthquakes. Numerical results showed that BRBs have high capability in seismic design of new structures and seismic retrofit of existing structures as well.

Experiencing earthquakes with different magnitude scales every few years, Iran is one of the most seismically active countries in the world.Therefore, it is very important to do research studies in terms of seismology before construction of bridges.Without considering seismic parameters, it would not be possible to design earthquake resistant bridges. Earth`s natural structure in different areas varies in relation with factors including kinetic energy at faults, global plate movements, velocity and maximum acceleration of plate displacements as well as the frequency and oscillation time.As mentioned before, demolition of an important structure like bridges, which is one of the basic elements in communication system among different areas leads to both heavy losses of life, and economic, social, hygienic and political losses. While a close and exact searching look at real seismic conditions of design site makes engineers able not only to prevent heavy costs of design and construction of bridges and to decrease earthquake losses significantly, but also to hold the communication system in service for the purpose of providing passages for firefighters to make all losses minimum.Studying occurred earthquakes such as Northridge and Kobe, which caused a lot of losses to different structures especially bridges contribute to feel the need of considering and studying available bridges in Iran under earthquake.According to the increasing growth of studies in field of vulnerability assessment and earthquake-resistant construction, this need was felt that a damper tested in building structures would be used as an option to make bridges earthquake-resistant.In this article, analytical studies have been done on an available concrete bridge, which is common in Iran based on structure types and its elements arrangement.This bridge was modeled in SAP 2000, and the model was run based on four earthquake records including Tabas, Kobe, Northridge and El Centro applying four different PGAs and nonlinear dynamic time-history analysis were carried out, then the steel accordion damper was installed in order to compare analysis results of model before and after the damper installation.The result showed a decrease in seismic response of bridge structure after damper installation and acceptable amount of energy absorption and losses by dampers, which contribute to energy-loss increment in different elements of the main structure. These results lead to the conclusion that steel accordion dampers are a suitable solution in earthquake-resistant design of bridges.