This paper aims to analyse the ductility of existing buildings to evaluate its influence in their seismic performance. This has been achieved through the retrospective analysis of an existing building in accordance with current seismic codes. This study has revealed the lack of guidance in the NCSE02 and the EC8 regarding the assessment of the ductility of existing buildings. This manuscript proposes a methodology to assess the ductility of Spanish existing buildings. For this purpose, this paper has implemented the American code procedure combined with the EC8 and the Spanish seismic code (NCSE02) requirements. A two-storey RC frame school located in the Spanish region of Huelva has been selected as a case study. Different versions of this school have been compared: as built, designed according to current best practice, EC8 provisions and NCSE02 provisions. To do so, different constructive features have been varied according to each of the ductility class requirements: geometrical properties and the reinforcement ratio of the structural elements. Nonlinear static analyses have been carried out to obtain the displacement ductility factor (μ) and the behaviour factor (q) of each model. Construction costs and the expected damage index have been determined and compared. Results have shown that the best performance, regarding the ductility and the costs, has been obtained with the models designed with deep beams. Conversely, models with wide beams, and where only the reinforcement ratios have been varied, have merely shown a slight enhancement of the resistant and ductile capacity. It has been concluded that the ductility affects the shear capacity, the seismic performance and the expected damage of RC buildings.

本文旨在分析现有建筑物的延性，以评估其对抗震性能的影响。这是通过根据当前的地震法规对现有建筑物进行回顾性分析来实现的。这项研究表明，NCSE02和EC8在评估现有建筑物的延展性方面缺乏指导。该手稿提出了一种评估西班牙现有建筑物延展性的方法。为此，本文结合了EC8和西班牙地震法规（NCSE02）的要求实施了美国法规程序。案例研究选择了位于西班牙韦尔瓦地区的两层RC框架学校。比较了这所学校的不同版本：按照当前的最佳做法建造，设计，EC8规定和NCSE02规定。为此，根据延展性等级要求中的每一项，改变了不同的构造特征：几何特性和结构元件的增强比。已经进行了非线性静力分析以获得位移延性因子（μ）和每个模型的行为因子（q）。确定并比较了建筑成本和预期损坏指数。结果表明，采用深梁设计的模型在延性和成本方面获得了最佳性能。相反，具有宽梁且仅改变了钢筋比率的模型仅显示出抗性和延性的轻微提高。得出的结论是，延性会影响钢筋混凝土建筑的抗剪承载力，抗震性能和预期破坏。