###### Abstract  
The concept of seismic resilience has been introduced in the design of buildings in the last decade. In this regard, the delay time may be defined as the time that occurs between the event and the moment the repair process begins. In the literature, only a few contributions have considered delay time, and even its definition is still under discussion. However, it is a key parameter in the assessment of resilience after earthquakes since it may significantly increase the total time after which a structure may be considered recovered. The principle at the base of the paper is that seismic structural health monitoring (S2 HM) may play a significant role in reducing the delay time. Therefore, delay time needs to be considered since it may significantly reduce the seismic resilience of structural systems. The paper aims to consider this important issue demonstrating the relationship between S2 HM and the assessment of the seismic resilience of buildings. In particular, the assumption herein is that the accuracy of the S2 HM may be described with different levels, and in correspondence with these levels, certain values of the delay time may be considered. In addition, the delay time is considered as a percentage of the total repair time. A multidimensional definition that includes the accuracy of S2 HM in the description of the delay time is herein proposed to be included in methodologies that aim to assess seismic resilience. seismic structural health monitoring; seismic resilience; delay time; earthquake 20232023202320232023202320232023202320232023220232023202322023220232202322023220232220232220232222222222222222222222222222222222222222222222  
repair time without considering the building's functional recovery process [10]. Another study [11] named this delay time as impeding time, which is due to indirect and external factors that delay the beginning of the recovery process. In this regard, several contributions considered these external factors (e.g., [8; 12; 13; 14]. REDi [4] considered impeding factors as those that consist of construction delays proposing to consider impeding times ranging from 5 days for inspection to around 50 weeks for some contractor, design, and finance delays (more details can be found in [4]). [PERSON] et al. [15] considered that the characteristics of human infrastructures and post-disaster decision making might considerably affect the recovery process. In addition, [16] considered that the decisions to repair and rebuild depend on unpredictable characteristics of the owners (e.g., income, ownership, time at current residence, earthquake insurance, etc.). Moreover, [17] demonstrated that implementing strategies to recover business is a key factor in reducing delay time by considering 22 businesses affected by the 2011 Christchurch Earthquake. Ref. [3] also considered the Christchurch Earthquake as a case study to support the definition of resilience as a process and particularly focused on how the prioritization of needs changes as time moves on following a disaster. Recently, [10] named mobilization time the range between the time of the earthquake and the time at which the repair process begins. This mobilization time consists of the time for building inspections, relocations of occupants and activities, and decision-making procedures (more details are found in [8]). In this paper, the time that runs between the time of the event and the beginning of the repair process is called delay time, considering a negative connotation to this time since it significantly reduces the seismic resilience of the system. The duration of delay time depends on several aspects, such as the width of the affected region, the vulnerability of the existing buildings, and the availability of resources for seismic structural health monitoring (S2 HM) or, more specifically, inspections. In particular, emergency decisions are strictly connected to the uncertainties of the structural state.