Change in modal parameters of cracked single-edge notched plain concrete Beams

CHANGE IN MODAL PARAMETERS OF CRACKED SINGLE-EDGE NOTCHED PLAIN CONCRETE BEAMS ∗ Luis A. Padr´on1, Juan J. Azn´arez1, H´ector Cifuentes2, Fernando Medina2, Orlando Maeso1 1University Institute SIANI, Universidad de Las Palmas de G.C., Las Palmas de G.C., Spain {lpadron,jjaznarez,omaeso}@siani.es 2Universidad de Sevilla, Seville, Spain {bulte,medinaencina}@us.es Abstract The aim of this work is looking into the possibility of capturing the change in the modal properties (natural frequencies, modal shapes and modal damping ratio) of plain concrete elements due to the presence of cracked areas by using a simple continuum damage zone numerical model. To do so, and as a first step, single-edge plain concrete beams were identified by experimental modal analysis with and without cracks in order to find out how cracking affects the first three flexural modes of the element. Then, numerical modal analysis was performed by finite elements in order to identify the material properties of the intact specimens by model updating and also check the experimental results. Finally, a boundary element – finite element coupled code was used to find a continuum model for the cracked single-edge notched beam able to reproduce the experimental results in terms of natural frequency shifts and modal damping ratios. It was found that, in order to reproduce the experimental frequency response functions, an overdamped damage zone is needed together with an equivalent crack length. Acknowledgements This work was supported by Subdirecci´on General de Proyectos de Investigaci´on of the Ministerio de Econom´ıa y Competitividad (MINECO) of Spain through the research project BIA2010-21399-C02-01/02 (coordinated between the Universidad de Las Palmas de Gran Canaria and the Universidad de Sevilla) and co-financed by the European Fund of Regional Development (FEDER). The authors would also like to thank Jacob Montesdeoca for his help in the preparation of specimens and tests; and Rub´en Darias, Jacob Rodr´ıguez, Ariel Santana and Ayoze M´endez for their help during the experiments. The three-point flexural tests were performed in the Laboratorio de Construcci´on of the Escuela de Arquitectura of the Universidad de Las Palmas de Gran Canaria. The specimens and auxiliary equipment were made in the Laboratorio de Hormigones, Tierras y Asfaltos of the EIIC of the same university. ∗This is a summary of the following article: Padr´on, Azn´arez, Cifuentes, Medina, Maeso, CHANGE IN MODAL PARAMETERS OF CRACKED SINGLE-EDGE NOTCHED PLAIN CONCRETE BEAMS, JOURNAL OF VIBRATION ENGINEERING & TECHONOLOGIES, 3(3), 253-265 (2015). The final publication is available at http://www.tvi-in.com/Journals/journaldetail.aspx?Id=201507031116022107188bbe06e143f 1