Seismic vulnerability assessment of existing buildings is an essential process for earthquake disaster management. It can support decision-makers to estimate critical response parameters and improve them. While several seismic vulnerability assessment techniques have been introduced over the past years, a detailed formulation to measure the vulnerability index of existing buildings along with the operative procedure is still lacking. Current standards and literature worldwide mostly propose simplified approaches (e.g. based on limited engineering analyses, visual inspection) to perform a rapid vulnerability assessment that can be useful when a large number of buildings should be analyzed. This paper presents a methodology to perform the seismic vulnerability assessment of existing buildings at collapse, analyzing a standard vulnerability index, and proposing alternative formulas. The methodology combines field investigations and experimental tests with nonlinear structural analyses. It has been applied to a case study that consists of an existing reinforced concrete school building to analyze and compare the proposed indices with respect to different ground motion selection procedures. Furthermore, a detailed comparison with alternative vulnerability indices from literature has been also performed.

现有建筑物的地震脆弱性评估是地震灾害管理的重要过程。它可以支持决策者估计关键响应参数并对其进行改进。虽然在过去几年中已经引入了几种地震脆弱性评估技术，但仍然缺乏一个详细的公式来衡量现有建筑物的脆弱性指数以及操作程序。世界范围内当前的标准和文献大多提出了简化的方法（例如，基于有限的工程分析、目视检查）来执行快速脆弱性评估，这在需要分析大量建筑物时非常有用。本文提出了一种在倒塌时对现有建筑物进行地震易损性评估的方法，分析标准易损性指数，并提出替代公式。该方法将现场调查和实验测试与非线性结构分析相结合。它已应用于由现有钢筋混凝土学校建筑组成的案例研究，以分析和比较针对不同地震动选择程序的建议指标。此外，还与文献中的替代脆弱性指数进行了详细比较。