In the last two decades, the process of urbanization and industrialization in developed countries has led to the formation of complex cities that are vulnerable to natural and human disasters. The advancement of information technology and the move towards smart cities have helped to improve urban management, but it requires careful planning to reduce vulnerabilities and increase infrastructure security. Urban planning should be done based on the principles of passive and defensive defense so that urban infrastructures are resistant to threats. This research has investigated the issues related to safety and infrastructure smartness in District 4 of Tehran Municipality. The purpose of the research is to identify and interact the necessary infrastructures to achieve resilience, analyze the factors affecting the resilience of urban infrastructures in a smart city and provide planning solutions to strengthen the resilience of infrastructures with a passive defense approach. The research method was designed in an exploratory-analytical way and observation, interview, library studies and questionnaire methods were used to collect information. Data analysis was also done with content analysis methods and various statistical tests and SPSS software was used for scoring. The results of the research show that there is a significant relationship between the environmental physical dimensions of urban planning and passive urban defense with a score of 4.16. The physical component of the environment is known as the most effective factor in reducing risks during the crisis in District 4 of Tehran Municipality. Finally, this research emphasizes that improving the resilience of smart city infrastructure with a passive defense approach can significantly reduce vulnerability.

In recent decades, resilience, passive defense and smart city have been considered for infrastructure planning and urban development. The safety and resilience of infrastructures is one of the fundamental and essential factors, the disruption of which causes crises in societies. Today, many problems and threats have affected human life. The present age has become the age of vulnerability, the cities are developing at the same time with different dimensions, they are facing natural hazards and technological crises, as well as social-security crises. This issue indicates that the development of cities, along with benefits and improvements, is accompanied by serious challenges that should be paid special attention to. Correct and comprehensive management and planning to deal with these crises and risks is essential.

Considering the importance of infrastructures in the city, including sensitive, important and vital; Such as water, electricity, city gas, telecommunication, transportation, health and treatment systems, etc., appropriate solutions should be made for their resilience and protection. These important and essential parts in any city may be attacked by the enemy, and in case of damage to the vital infrastructure, a lot of damage will be done to the entire city's systems and the life of citizens will be disturbed. According to the characteristics of the smart city, it can be said that the infrastructures become more important in the smart city. Planning for the growth and development of the smart city is facing many challenges. In today's societies, the smart city has a special place in cities and has become an influential field in urban planning. With the expansion of urbanization and the increase of urban population, cities are facing many challenges that cannot be solved by traditional methods. In this regard, information and communication technology has had a significant impact on the urban society in recent years and the trend is increasing. In this context, the concept of "smart city" has gained a special place and has become one of the influential fields in urban planning and management. This approach is based on the use of new technologies to improve efficiency, productivity and provide urban services to citizens. Therefore, the use of smart technologies along with new planning approaches can lead to solving the challenges of today's cities and improving the quality of life of citizens.

In this research, the main infrastructures in the 4th district of Tehran Municipality will be examined and discussed in the form of 6 chapters, and by studying planning and smart building in the world, the country and Tehran, the possible effects and challenges on them will be examined, and finally Appropriate solutions will be presented in accordance with the requirements of passive defense and the findings of the research will be analyzed and in the final summary, a way to mention possible solutions will be taken.