تبیین مفهوم شکنندگی شهر و بررسی ابعاد و مؤلفه های های شهر شکننده مبتنی بر مرور نظام مند

Introduction: Currently, more than half of the world's population resides in cities. The important issue is that, due to demographic trends, cities are significantly facing with the global challenges of the new age. One of these challenges is faced with natural disasters that cause social vulnerabilities along with economic losses. The most incidents that can be mentioned are; extreme climate changes, earthquakes, floods, storms, avalanches, landslides, lightning, and tsunamis. The cases mentioned are among the events that mankind is facing today, and it should be noticed that every day these disasters lead to the loss of a large number of people's life. It should also be noted that the planned structure of cities through factors such as the rapid and uncontrollable growth of urbanization and development of new residence patterns, changes in national and local government and its spatial organization, weak local governments, and social and income inequality are gradually destroying. According to the issues mentioned, one of the important challenges that can be pointed out is that cities are facing severe pressure and only a few of them are equipped with the tools to overcome challenges. Another point that should be mentioned is that the cities have suffered a kind of premature fragility, and in other words, the threshold of fragility of the cities has been greatly reduced and they have become a chaotic environment for residing. Nevertheless, the fragility of the city is not continual, and by offering instructions, the threshold of fragility in cities can be increased to a great extent, and instructions can also be provided for the restoration of cities. Also, by mentioning that cities are different from each other in the aspects of economic and cultural identity and how to deal with risk, each of them should have different solutions to control the fragility of the city. Therefore, the current research can significantly change the process of fragility by the perception of fragility and recognizing components of fragility in cities.
Methodology: The present study, taking into account the preferred report in the field of structured review guidelines, by providing a strategy for searching articles based on the words "fragility", "fragile city", "urban fragility" and "fragile state" in valid citation databases, from a structured review based on a 7-step model (question selection, inclusion criteria, finding studies, selecting studies, evaluating the quality of studies, extracting data, analyzing and presenting results) has been started, and in total, 722 sources (including articles, books, and official reports)  have been found and after going through 7 steps, 86 sources were selected for deeper studying.
Results: The findings obtained from the review of the theoretical basics and considerations suggested by researchers in the field of fragility indicate that urban fragility is a new concept in the field of urban planning and management and is described as follows; urban fragility means the city's weakness and fragility against a set of multiple risks, that happens when a city lacks legitimacy and effective institutions, the existence of multiple risks in different dimensions (economic; social; institutional; environmental, economic, social and political conditions of the people of the society; because of the unfavorable performance of the city, international relations) that do not have the suitable functionality to perform their main tasks before, during and after facing the shocks and lead to different forms of fragility in relation to the city and society. It is also necessary to mention that fragility is unavoidable and reversible and can quickly or gradually penetrate into cities and lead to the creation of permanent risk and disturbance in their development process. It is worth mentioning that the degree of fragility of a city against risks is evaluated with the sum of components such as pre-risk conditions, risk characteristics, and reactions to overcome the risk.
Discussion: The conducted studies indicate that the components that cause urban fragility have a continuous sequence and appear continuously. The increasing growth of urbanization leads to the creation of slums. Since the slum dwellers suffer from urban poverty due to the lack of access to essential services and proper jobs, in addition to inequalities in social issues and income, there are also issues such as tension, violence, and urban conflict which is caused by inequity. Therefore, according to the statements of researchers and thinkers in the field of urban issues, urban fragility does not appear due to one factor, but a set of risks and challenges are also involved in its emergence. Also, increasing the components of the rapid growth of urbanization, informal residence, unemployment, urban violence, and facing natural disasters indicates that the mentioned components include all social, economic, and environmental dimensions. It is worth mentioning that most of the research conducted in this field has identified the social, economic, and environmental dimensions and components, and due to the emergence of the concept of urban fragility, governmental-institutional dimensions; economic, social, and political conditions of society and international relations have not been comprehensively and accurately under the feasibility studies and practical evaluation.
Conclusion: The findings obtained from this study indicate that cities that make investments to address the main risks will grow at an increasing speed in the future. In other words, it can be said that investments that lead to reducing violence, improving security, and increasing the capacity of authorities and citizens to prepare and respond to disasters, prevent the fragility of the city. Therefore, urban planners, policymakers, researchers, and local managers should consider policies to reduce urban fragility for achieving urban resilience in their development plans and take measures to improve and promote the fragile infrastructure and expand livelihoods.