This paper analyses the seismic vulnerability of various rammed earth medieval fortifications situated in Southeastern Spain, where seismic events with intensity over VII have taken place in the last millennium, using the vulnerability index method. This method begins with the choice of a certain initial value, V₀, of the vulnerability index, which is obtained from a preset range between maximum, \({\text{V}}_{0}^{ {\rm max} }\), and minimum, \({\text{V}}_{0}^{ {\rm min} }\), values, which are likely for vulnerability indices, according to the constructive material characteristics and based on expert judgments. Rammed earth structures have not yet been studied using the vulnerability index method, despite the fact that they are quite common medieval structures in Spain and other countries in the Mediterranean region, many of which are also heritage sites, and hence are legally protected. Intervention priorities on them have been determined from the results in this paper with the aim of reducing their seismic vulnerability. For the different rammed earth techniques, a proposed primary value V_p = 0.76 together with some other material modifiers (construction typology and quality, current material porosity and density, and superficial deterioration) make the range of values V₀ vary between 0.58 and 1.02. Moreover, structural behavior modifiers (M_K) have been adapted to the various defensive rammed earth structural typologies used for these fortifications allowing us to obtain individualized vulnerability index values. Three rammed earth fortifications damaged by historical earthquakes and located in SE Spain have been used to validate the method, in which values of V_0med range between 35.2 and 89.1% and upwards and the vulnerability index I_Vmed may vary between 27.9 and 70.7% and upwards as compared to those used by other authors for castles. Besides, the proposed method has been used by carefully choosing six rammed earth fortifications (two towers, two walls and two castles) in SE Spain which are representative of different construction systems, structural typologies and topographies. Furthermore, the mean damage grade and the probability of its occurrence is determined for each fortification based on PGA data and site effects, taking into account a probabilistic seismic scenario for a 975 year return period, in accordance with existing legislation. In the end, direct relations are established between the seismic vulnerability and the types of material and the typology of the fortifications. We have carried out a sensibility analysis in order to learn about the influence of the constructive technique, the material condition and the structural typology on the damage grade value. The results show that lime-crusted rammed earth technique and tower typologies are the most vulnerable structures while topography is somehow less important. The results suggest that for half of the structures analyzed for the given scenario the probabilities are above 80% for damage grade 4 and 5 (EMS-98).

中文翻译：

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西班牙东南部中世纪夯土工事的地震易损性分析

本文利用脆弱性指数法分析了西班牙东南部各种夯土中世纪设防的地震脆弱性，那里在过去的千年中发生了VII级以上的地震事件。此方法从选择漏洞指数的某个初始值V ₀开始，该值从最大值\（{\ text {V}} _ {0} ^ {{\ rm max} } \）和最小值\（{\ text {V}} _ {0} ^ {{\ rm min}} \），这些值很可能根据构造性材料特征并根据专家判断得出脆弱性指数。尽管夯土结构是西班牙和地中海地区其他国家中相当普遍的中世纪结构，但尚未使用脆弱性指数方法进行研究，但其中许多也是遗产，因此受到法律保护。根据本文的结果确定了对它们的干预优先级，目的是降低其地震脆弱性。对于不同的夯土技术，建议的初始值V _p  = 0.76以及其他一些材料改性剂（构造类型和质量，当前材料的孔隙率和密度以及表面变质）使值V处于范围内₀在0.58和1.02之间变化。此外，结构行为修饰符（M _K）已适应于这些防御工事所使用的各种防御性夯土结构类型，从而使我们能够获得个性化的脆弱性指数值。已使用位于西班牙_东南部的三个受历史地震破坏的夯土设防来验证该方法，其中V _0med的值介于35.2％和89.1％之间，且_较高，脆弱性指数I _Vmed与其他作者使用的城堡相比，该值可能在27.9％至70.7％之间，甚至更高。此外，通过仔细选择西班牙东南部的六个夯土防御工事（两个塔，两个墙壁和两个城堡）来使用所提出的方法，这些防御工事代表了不同的建筑系统，结构类型和地形。此外，根据现行法规，根据PGA数据和工地影响，针对每个工事确定平均破坏等级及其发生的可能性，并考虑975年回归期的概率地震情况。最后，在地震易损性与材料类型和工事类型之间建立了直接关系。我们进行了敏感性分析，以了解构造技术，材料条件和结构类型对损伤等级值的影响。结果表明，石灰结皮夯土技术和塔型是最脆弱的结构，而地形则不那么重要。结果表明，对于给定场景分析的一半结构，其4级和5级损坏（EMS-98）的概率高于80％。