Suchergebnisse

The authors thank the PREDITEST Company, from the Czech Republic, and in particular Svoboda, for support in MMM equipment, measurements, and scientific discussions ; Inelastic deformation of metallic materials is one of the most effective mechanisms for the dissipation of energy input to a structure by an earthquake. Metallic dampers are special devices that resort to this source of energy dissipation, proving to be a cost-efficient solution for the seismic protection of structures. Two important issues arise when implementing metallic dampers in real structures: (1) Inelastic deformations cause damage that must be quantified after an earthquake to decide upon their eventual replacement; (2) dampers must possess an energy dissipation capacity large enough to endure severe earthquakes. This paper focuses on a particular type of metallic damper consisting of slit-plates made of stainless steel, applied to reinforced concrete frames with rocking columns at the first story. In particular, a new damage index based on the metallic magnetic memory (MMM) method is proposed and validated experimentally to quantify the damage of slit plate dampers subjected to cyclic loadings. Further, the seismic response of a frame with rocking columns that incorporate the damper is obtained to demonstrate that it can endure severe earthquakes without failing, and to emphasize the relevance of the proposed MMM damage index that would make its replacement after a severe earthquake unnecessary. ; This research was funded by Consejería de Economia, Innovación, Ciencia y Empleo, Junta de Andalucía, grant number TEP-02429, by Ministerio de Economía, Industria y Competitividad, Gobierno de España, grant number BIA2017 88814 R, and received funds from the European Union (Fonds Européen de Dévelopment Régional). The APC was funded by Ministerio de Economía, Industria y Competitividad, Gobierno de España, grant number BIA2017 88814 R.

This paper shows the acoustic emission (AE) analysis recorded during the loading process of reinforced concrete (RC) structures subjected to bidirectional seismic loadings. Two waffle plates (bidirectional) supported by isolated square columns were tested on a shaking table with a progressive and increasing ground acceleration until the final collapse. Each specimen was subjected to a different loading history. A relevant delay in the beginning of the significant AE energy is observed as the peak value of the ground acceleration increases. Based on this result, a new AE temporal damage index (TDI), defined as the time difference between the onset of the significant AE activity and the onset of the loading that causes this AE activity, is proposed and validated by comparing it with the plastic strain energy released by the concrete, typically used as a reliable damage level indicator. Good agreement was observed for both specimens and seismic inputs. ; This research was supported by the regional government of Andalucía, Consejería de Innovación, Ciencia y Tecnología, Project TEP-02429, by the Spanish Ministry of Economy and Competitivity, research project reference MEC BIA2017 88814 R and received funds from the European Union (Fonds Européen de Dévelopment Régional).