Theoretical Guidelines and challenges affecting the interventions of structural restoration in architectural heritage

Interventions related to the structural restoration of architectural heritage, due to having the dual goal of protecting human lives and preserving cultural property, can create more and wider risks compared to other types of restoration interventions for continuity of the historic buildings and the safety of their users. Therefore, how to design and implement structural interventions based on clear and applicable theoretical foundations becomes necessary. However, it seems that the existence of a level of overview of the theoretical issues and also the lack of clarity in the understanding and application of some guiding principles have confused the restorers and structural engineers in the field of creating a proper connection between the theoretical topics and practical interventions. From this point of view, the research has investigated the written recommendations of the experts in this field in order to find applicable guidelines and recognize the challenges facing their proper application in connection with structural interventions of architectural heritage. The experts have been selected from those who have international reputation in related fields and practical experience and Authentic written researches have written about this topic. The research is applied in terms of purpose and follows a qualitative approach. The required data was obtained through library studies relying on the written sources of selected experts, and the information analysis has been done based on the content analysis of these sources and with the help of the software analysis technique with MaxQDA software. The research results include: a) conservative and technical guidelines in related to the proper orientation of structural interventions, b) the challenges of applying these theoretical guidelines and c) solutions to overcome these challenges. Conservation guidelines include conservation of values, maximum conservation of authenticity, compatibility of materials and techniques, conservation of structural integrity, compliance with conservation goals, balance of attitude, degree of similarity of action, distinctiveness of action, minimum possible intervention and relative reversibility of action. Technical guidelines can also be divided into adaptability to the status qua, structural efficiency, feasibility, controllability, maintainability, durability of intervention and final outcome measurement of the action. Also, the challenges facing the application of these guidelines are divided into three categories: 1) challenges affected by the contradiction between the philosophy of conservation and the requirements related to the safety level, 2) internal conflicts between some of the conservative guidelines and 3) the challenges caused by the impact of some external issues such as financial resources on interventions. Proper structural restoration to overcome these challenges should be presented in a way that pays attention to points such as the need to review and establish specific standards and risk levels for historical structures, perform accurate and combined diagnostic studies before deciding, Humility in choosing less destructive modern solutions with greater reversibility, Using an incremental approach to determine the minimum possible intervention, applying lower levels of reliability and considering parallel arrangements to minimize the possibility of structural failure and use sustainable financial resources without applying external pressures.