Shaking Table Tests Determining Frequency and Stiffness Before and After Strengthening of a Confined Masonry Wall Without an Opening

Abstract

Shaking table tests are planned in order to deepen the understanding of the behavior of confined masonry structures with or without openings. This paper presents the observations from a series of shaking-table tests done on a 1:1 scaled confined masonry wall model without openings (model CMF). Frequency and stiffness changes before and after GFRP wall strengthening are analyzed. The main targets of this research are assessment of the influence of location and area of the opening on the load-bearing capacity, rigidity and ductility of confined masonry, definition of appropriate systems for improvement of the stiffness, load capacity and ductility of the system and contribution in the assessment procedures proposed for masonry building in Eurocode 8. The initial frequency of the undamaged model CMFuS is 24,63 Hz, while at the end of the testing, the frequency decreased to 10,60 Hz. This emphasizes the reduction of the initial stiffness of the model due to damage, especially in the masonry and tie-beam to tie-column connection. After strengthening of the damaged wall, the natural frequency increases to 19,78 Hz. This highlights the beneficial effect of the strengthening. After completion of dynamic testing at CMFS, the natural frequency is reduced to 12,48 Hz.