FUll-scale shake table experiments and vibration tests for assessing the effectiveness of textile materials for retrofitting masonry buildings

Abstract

Full-scale shake table seismic experiments and low amplitude vibration tests on a masonry building are carried out to assess its seismic performance as well as study the effectiveness of a new textile material for retrofitting masonry structures against earthquakes. The un-reinforced and the retrofitted with glass fiber reinforced polymer (GFRP) strips masonry buildings were subjected to a series of earthquake excitations of increasing magnitude in or-der to progressively induce various small, moderate and severe levels of damage to the ma-sonry walls. The performance of the original and retrofitted building states is evaluated. Changes in the dynamic characteristics (lowest four modal frequencies and damping ratios) of the building are used to assess and quantify the damage states of the masonry walls. For this, the dynamic modal characteristics of the structure states after each earthquake event were estimated by performing low-amplitude impulse hammer and sine-sweep forced vibration tests. The retrofitting actions restored the stiffness characteristics of the reinforced masonry structure to the levels of the original undamaged un-reinforced structure. The results show that the despite a similar dynamic behavior identified, corresponding to reduction of the modal frequencies, the un-reinforced masonry building was severely damaged, while the rein-forced masonry building was able to withstand, without visual damage, the induced strong seismic excitations. The GFRP textile material, optimally wrapped along the masonry walls following existing guidelines, was proven to be very effective in reinforcing the masonry building to withstand earthquake events significantly larger in magnitude than the ones caused severe damage to the un-reinforced building.