فصلنامه پدافند غیرعامل
سال دوازدهم شماره 3 (پیاپی 47، پاییز 1400)

Progressive collapse is defined as the propagation of some primary local failure from one member to another that eventually leads to the failure of the entire structure or a large part of it. Potential hazards or incidents that can result in progressive damage include fire, collision, explosion, and earthquake. In the mechanism of progressive collapse, a local failure, such as the major damage or removal of a column, causes a total and significant collapse that will lead to the collapse of the entire structure. The aim of the present study is to investigate the progressive collapse in a special braced wind tunnel retaining structure with the scenario of simultaneously removing one of the main columns and bracings in the base level. In this study, a wind tunnel retaining space structure that supports the main structure of the wind tunnel is considered. This high-rise steel structure is braced with a composite structural system, which incorporates various failure scenarios. The models are first analyzed and designed in ETABS software and their output is transferred in SAP2000 software and then nonlinear static analysis is performed on those models. The results show that in case of the removal of bracing in the event of an explosion, only in members close to the removed elements, an increase in shear is observed. The amount of displacement of the structure in nonlinear static analysis is equivalent to removing one column and bracing more than the previous case. The results show that by removing the column and bracing simultaneously, the progressive collapse will probably mostly occur in elements close to the part to which the failure scenario is applied.

Experiences from previous wars have shown that the science of geomorphology plays an important role in the implementation of offensive and defensive plans, the selection of settlement areas, the dispersion and the ready points. Therefore, geomorphological factors play an important role in adopting effective measures for passive defense. This study aims to investigate the geomorphological features of the coasts of Abadan district from the perspective of passive defense to identify the geomorphological strengths and weaknesses of the region. Preparing the SWOT method for application in the passive defense studies requires refining the basic concepts, as the basic concepts in passive defense studies are different from other fields of study. In passive defense studies, threats and opportunities of the external environment should be considered separately and differentiated from their internal counterparts. For example, a weakness can be considered an opportunity from another point of view, or a phenomenon that is considered strength from another point of view may be a weakness. The results show that vegetation as a whole has a positive effect on passive defense in the region. According to the geomorphological map of the region, the Arvand River is a flood plain and a part of it is a tidal wetland (Shalaheh and Khosrowabad villages). This tidal section is used to irrigate the palm-groves. The whole area is flat and there is a view of the facilities and personnel for the military, in both the Iranian and Iraqi sides. Some elevated features are created artificially in some areas but there are no naturally elevated geomorphological forms. The valleys and plains are less exposed to floods.

Nowadays, gait recognition is one of the biometric methods that receives more and more According to the cost-benefit principle in passive defense, the results of research on the behavior of shear walls show that the steel shear wall system will save about 50% in steel consumption compared to the bending frame system. The steel shear wall system has shown good performance as a lateral bearing system resistant to natural and man-made threats such as earthquakes and explosions, in addition to having a high performance and ductility and being light compared to concrete shear walls. Despite these advantages, this system has not yet been widely used in Iran. In this paper, the strip model is used as a method for the analysis of steel shear walls. In this model, the sheets of steel panels with oblique strips and the same angle are replaced as the tensile field. In this research, the effect of the number of band members used in the model and the slope angle in analyzing the behavior of this lateral beam system is demonstrated. In the end, it is concluded that the number of strip members and the angle of inclination have a negligible effect on the elastic behavior of the system and if linear static analysis for a thin steel sheer wall without hardeners is presented, interlayer panels can be modelled with 10 tape members per panel, as recommended in the Canadian regulations. However, the inelastic stiffness and response of the thin steel shear wall system without hardeners can be accurately achieved by modeling the interlayer panels with 30 strip members and an angle of 45 degrees.

Islands are generally considered strategic points for enemy missile and drone strikes. Therefore, due to the vulnerability of these islands to such attacks and the need for sustainable energy supply, the concept of resilience is very important in the day-ahead scheduling of energy resources on the islands. On the other hand, with the increasing prevalence of emerging resources such as electric vehicles, electrical storage, and demand response programs in microgrids, the need for integrated scheduling to use the capacity of these resources to improve the resilience of these networks has increased. To this end, this paper examines a two-stage scheduling approach to reduce the daily operating costs and improve the resilience of an island microgrid integrated with wind turbines. In addition, the effects of coordinated scheduling of emerging energy sources, including grid-connected electric vehicles, an electrical storage system, and shiftable electrical demands are evaluated to improve the daily operating costs and system resilience. The resilience index is considered as the sum of the cost of load shedding and the cost of increased power production in the event of an enemy attack on the wind turbines. Therefore, the proposed model determines the best operation strategy under normal conditions in such a way that, in the event of an enemy attack on the wind turbines, the lowest cost of load shedding and the lowest cost of increasing production in the presence of emerging energy sources will be tolerated by the islanding microgrid.

To reduce the effects of natural disasters, the resilience of urban areas is examined. One of the principles of resilience in cities is the improvement of the infrastructure resilience in natural disasters. In this regard, one of the basic steps is the resilience of key city centers and facilities. Therefore, in this study using the combined method of AHP and TOPSIS, the resilience of flood-vulnerable buildings is measured. After collecting the required data and information, the authors first obtained the effective criteria and sub-criteria in ranking the resilience of buildings against floods. Then, the final weight of each of the important vulnerable centers of the city was calculated and the options were ranked by the TOPSIS method. The results show that the key centers vulnerable to floods in descending order, are the University of Technology, the Payame Noor University, the Amiran Hotel, the University of Architecture and Art and the Blood Transfusion Center with the weights of 1.000, 0.520, 0.297, 0.273 and 0.153 respectively. The Blood Transfusion Center has the least and the University of Technology has the highest resilience.

This study has been conducted to investigate the ability of prestressed concrete slabs against explosion with passive defense objectives by the structural method. In this research, one-way and two-way concrete slabs have been modeled with Abaqus finite element software.  The dynamic analysis has been performed by the explicit step-by-step time history method. The non-linear plastic failure model has been used for the concrete behavior, whilst a linear model has been used for the steel and prestressed tendons. Explosive loading has been applied to the slab samples experimentally using the CONWEP model and free boundary conditions have been defined for the edges of the studied slabs. The results of the finite element model shows that the maximum stress in prestressed concrete reaches three times the stress experienced in the reinforced concrete. Also, prestressing the slab reduces the maximum deformation by about 3 cm compared to the reinforced concrete slab. The results show that the behavior of concrete against explosion is remarkably improved by prestressing. However, the optimal amount of prestressing and the distance of the tendons required to improve the slab behavior against explosion, can be calculated through more modeling. It can be said with certainty that prestressing is a good way to improve the behavior of slabs against explosion in explosion-proof defensive fortifications. The results show that the effect of slab geometry, whether it is one-way or two-way and the location of the explosion, affect the values of stress and deflection due to the explosive load.

The electromagnetic threats caused by narrowband and wideband electromagnetic pulses are one of the emerging threats. One of the targets of these threats is the power system. The power system has three main parts: production, transmission and distribution.   In this article which is based on SWOT analysis, 40 people are selected using the Cochran's formula from a group of experts from the electricity industry, the military and academic centers to rate the SWOT points. Since the strategies are oriented toward defensive strategies, 6 defensive, 4 conservative ,3 offensive and 3 competitive strategies are presented by combining the discussed points. From these strategies, 47 appropriate strategies are developed to reduce the vulnerability of the power system, with the prospect that if the enemies of the Islamic Republic use these threats against the country's power system, least damage is imposed on vital infrastructures and this industry can continue its activities.

Vulnerability can be attributed to an inherent defect in the specific dimensions of the city 's environment, which is prone to damage due to the biological and physical properties or design characteristics. Studying the structures of a city and micro-zoning its vulnerability from the perspective of passive defense is a step towards the future prospects of a safe city. The main purpose of the present study is to study the vulnerability challenge in urban infrastructure from the civil defense point of view, and the anticipated approach is the application of modeling for identification of these infrastructures. The domain of the present study is the Boroujerd city with the population of 240654 and the area of 33065884 square meters. This research is applied-research in terms of purpose and descriptive-analytical research (based on the approach of spatial-model studies) in terms of methodology. The indicators of special infrastructure, emergency, general, public and management services are classified and extracted in the form of 1062 infrastructures. In order to measure the proximity pattern, 14 layers which are effective on vulnerability are identified and using Anp-dematle-GIS combined analysis, the weighting of distance maps for them is designed and standardized. The FUZZY OVERLAY tool in ArcGIS software is used for spatial distribution and micro-zoning of urban infrastructure vulnerabilities. Spatial results and micro-zoning of vulnerability in Boroujerd city show that 539 infrastructures, namely 50.47% of the infrastructures are in a totally vulnerable situation. It should also be noted that about 59% of the city's area is in a situation from vulnerable to absolutely vulnerable, which shows the importance of the principles and requirements of passive defense in this city.