The in-plane stiffness of single straight-sheathed timber floors is normally supposed to be not sufficient to confer suitable seismic behaviour to the building. However, accurate evaluations of the in-plane behaviour of timber diaphragms and the effects of their deformability on the building response are difficult, especially for unreinforced masonry (URM) buildings. Various stiffening interventions of floors are possible; among them, the use of an additional layer of boards at 45° often demonstrates optimal behaviour as it combines the advantages of partial stiffening with minimum mass increase. This work was focused on the experimental characterisation of a stiff timber floor through cyclic loading testing of a three-dimensional full-scale specimen. The effects of in-plane flexibility and the non-linear behaviour of floors on the global response of URM buildings were evaluated by analysing the response of two buildings: a regular building and a building irregular in both plan and elevation. Analyses were conducted using a non-linear macro-element model to simulate the non-linear behaviour of masonry and the hysteretic behaviour of floors. The results showed that the seismic capacity of an URM building may be worsened by excessive stiffening of floors and/or mass increase.

中文翻译：

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木地板不规则无筋砌体房屋的抗震能力

单层直护木地板的面内刚度通常不足以赋予建筑物适当的抗震性能。然而，对木隔板的面内行为及其变形对建筑响应的影响的准确评估是困难的，尤其是对于无钢筋砌体 (URM) 建筑。可以对地板进行各种加固干预；其中，使用额外的 45° 板层通常表现出最佳行为，因为它结合了局部硬化和最小质量增加的优点。这项工作的重点是通过 3 维全尺寸试样的循环加载测试来表征硬木地板。通过分析两座建筑物的响应，评估平面内柔性和楼层非线性行为对 URM 建筑物全局响应的影响：常规建筑物和平面和立面不规则的建筑物。使用非线性宏观元素模型进行分析，以模拟砌体的非线性行为和地板的滞后行为。结果表明，URM 建筑物的抗震能力可能会因楼板过度加固和/或质量增加而恶化。