# Regional Seismic Damage Simulation of Corroded RC Frame Structures: A Case Study of Shenzhen City
## 1 Introduction  
Reinforced concrete (RC) structures in coastal areas are susceptible to chloride ion attack. On the one hand, airborne chloride ions can diffuse into RC structures over time [1]; on the other hand, the use of sea sand and sea water in RC structures has been observed in some coastal areas [2]. If the chloride concentration in concrete exceeds certain threshold, reinforcements in concrete could experience severe corrosion and the seismic performance can be seriously impaired. For example, more than 7000 RC buildings collapsed after the \(M_{\mathrm{w}}\) 7.8 Pedernales, Ecuador earthquake [3]. According to site inspections, the use of sea sand caused severe reinforcement corrosion, which resulted in poor seismic performance of local RC structures, as shown in Figure 1. Therefore, it is important to take chloride-induced corrosion into account when assessing the seismic performance of coastal RC structures. Regional seismic damage prediction is a useful tool for assessing the seismic resilience of regional buildings [4; 5; 6]. In a pre-earthquake scenario, regional seismic damage prediction can help to identify vulnerable spots of regional buildings; while in a post-earthquake scenario, it can assist in assessing the severity of the disaster [7], which provides references for emergency response and disaster relief. To date, regional seismic damage prediction methods can be categorized into the following three types: (1) seismic fragility method, (2) capacity spectrum method, and (3) time history analysis (THA)-based method. The seismic fragility method is developed based on historical seismic damage data or building seismic fragility data obtained through a numerical simulation [8; 9; 10; 11]. This method can be used to predict the seismic damage of buildings according to ground motion intensities (e.g., spectral acceleration and peak ground acceleration). The capacity spectrum method adopts pushover analysis to predict seismic responses of buildings [5; 12], which considers the nonlinear capacity of buildings and the spectral properties of ground motions. Such a method is simpler and more efficient than the THA-based method [13]. The THA-based method uses the multi-degree-of-freedom (MDOF) model or a refined finite element model, which can better simulate the dynamic responses of buildings and fully consider the time/spectral domain characteristics of ground motions. Powered by high-performance computing [14; 15], the THA-based regional seismic damage simulation method has had wide applications in previous studies [4; 6; 16; 17; 18; 19]. The THA-based regional seismic damage simulation method has also been adopted into the Natural Hazards Engineering Research Infrastructure SimCenter framework [20]. Although the aforementioned three methods have been extensively applied, related research on regional seismic damage prediction of corroded RC buildings in coastal areas is very limited. Current studies on the seismic performance of corroded structures has mainly focused on component and structural levels. At the component level, a large number of experiential studies have been conducted to investigate the seismic performance of corroded RC components [21; 22; 23; 24; 25]. At the structural level, numerical simulations of corroded RC buildings and bridges have been reported by numerous researchers [26; 27; 28; 29; 30; 31; 32]. Nevertheless, at a regional level, related study on regional seismic damage prediction of corroded RC buildings is limited. Only a few cases can be found on the seismic damage prediction of civil infrastructures. For example, [PERSON] et al. [33] conducted a seismic damage simulation of oil and gas pipelines and considered the influence of pipeline corrosion. From the above discussion, this work mainly focuses on the regional seismic damage simulation of corroded RC buildings using THA.