Experimental study of in-plane hysteretic behavior of unreinforced masonry walls retrofitted with engineered cementitious composites (ECC)

Abstract

One of the newest retrofitting techniques in Unreinforced Masonry (URM) structures was investigated in this study. URM structures are among the most widely used and conventional structures in the world while vulnerable due to the lack of proper shear resistance against applied lateral loads including seismic forces. The technique, classified in the group of surface treatment methods, is retrofitting with Engineered Cementitious Composite (ECC), which demonstrates multiple cracking properties. This property provides an ability to withstand tensile deformations and the strain-hardening behavior for the composite. The improvement of the properties such as low tensile strength, softening and brittle behavior of URM walls has caused the ECC to become a suitable material for seismic retrofitting of them. In the present research, the impact of external application of a layer of ECC on an URM wall was experimentally evaluated and examined. Initially, a series of tests on materials were carried out to achieve various ECC mechanical properties such as tensile stress-strain, hardening, and multiple cracking behaviors. Then, mechanical behavior of the retrofitted small-scale masonry specimens was evaluated. Finally, full-scale wall specimens were built and tested under cyclic loading. Plain specimens were tested as reference ones to evaluate the performance of the retrofitting method. The results indicate that the retrofitting of unreinforced masonry walls with this technique can lead to an increase in lateral strength, integrity, energy dissipation, and prevention of brittle fracture.