The existing reinforced concrete buildings typical of the Mediterranean area commonly have poor seismic performance and high vulnerability to the seismic events. As demonstrated by recent post-earthquake reconstruction processes, they commonly exhibited significant damage to structural components and to infills and partitions resulting in very high repair costs. This suggests that effective seismic strengthening interventions should aim at both improving the safety and reducing the expected annual losses. Nowadays, the seismic retrofitting of existing RC buildings by using base isolation is becoming popular because of the high effectiveness as seismic protection strategy. However, the high costs of installation are limiting the widespread in the common design practice. In this context, a unique design parameter capable of combining the increasing seismic safety, the cost of installation and the reduction of the expected losses can be useful to draw simple cost-benefits considerations. This research work proposes a PBEE-based methodology to quantify the Pay-Back Time (PBT) of seismic retrofit solutions for existing RC buildings. The non-linear response of base isolated building is assessed and a comparison with different strengthening solutions is proposed to show the applicability of the PBT as a unique design parameter to select the most effective retrofit solution. A database of 59 RC buildings retrofitted by using base isolation during the L’Aquila reconstruction process, where actual retrofit costs are available, is used for the validation. Finally, these data are used to calibrate a simple formulation of the PBT to be used in the design practice.

地中海地区典型的现有钢筋混凝土建筑通常抗震性能差，并且容易受到地震影响。正如最近的地震后重建过程所表明的那样，它们通常对结构部件以及填充物和隔断均表现出重大损坏，从而导致很高的维修成本。这表明有效的抗震加固措施应既旨在提高安全性又要减少预期的年度损失。如今，由于作为防震策略的有效性很高，使用基础隔离对现有RC建筑物进行抗震改造变得很流行。但是，高昂的安装成本限制了通用设计实践中的广泛使用。在这种情况下，能够结合不断提高的地震安全性，安装成本和减少预期损失的独特设计参数，对于得出简单的成本效益考虑十分有用。这项研究工作提出了一种基于PBEE的方法，用于量化现有RC建筑物的地震改造解决方案的投资回报时间（PBT）。评估了基础隔震建筑的非线性响应，并与不同的加固解决方案进行了比较，以表明PBT作为唯一设计参数选择最有效的改造解决方案的适用性。通过对L'Aquila重建过程中使用基础隔离进行改造的59座RC建筑物的数据库进行验证，在该数据库中可获得实际的改造成本。最后，