عنوان مقاله [English]
Performance of fiber reinforced Engineered Cementitious Composites (ECC) strengthened by non-ductile Reinforced Concrete (RC) frames with hollow clay brick masonry infill subjected to quasi-static in-plane loading was experimentally assessed herein. The suggested strengthening technique was used for increasing the lateral strength of infilled RC frames and retaining the integrity of the masonry infill wall during earthquake loading. Initially, the mechanical properties of ECC and masonry elements were tested. The ECC was made of water, cement, silica fume (5% of cement weight), Zeolit (5% of cement weight), silica sand, fly ash, superplasticizer, and Poly-Vinil-Alkaol fibers (1.5% of the whole volume of the concrete). Cylinder and Dog-bone specimens were cast and tested to evaluate the compressive and tensile stress-strain behavior of ECC concrete. Afterward, three RC specimens with one-third scale and one bay-single story. Of these specimens, one frame was tested as built without infill (BF) and another frame as built with infill (IF-E0), and the rest of the frames were retrofitted using ECC as an overlay on the masonry wall (IF-DF-E20-1). The infilled frame strengthening using ECC (IF-DF-E20-1) provided lateral strength, stiffness, and energy dissipation capacity of 2.31, 1.11, 1.37 times those of the hollow clay brick masonry infilled frame (IF-E0), respectively. Furthermore, the obtained backbone curves are idealized using a two-line model. The relative displacement of each floor is an important issue in the structural and non-structural seismic designs; thus, the initial cracks (flexural in columns, diagonal in beam-column joint, flexural in beams, cracking in the interface of the frame and infilled bricks, crushing of bricks, shear crack in column, sudden crushing of infill, and concrete crushing of column) at the respected displacement was analyzed here. According to the results, the proposed strengthening technique not only increased the lateral strength and energy absorption capacity of the infilled frame but also provided a reasonable system overstrength and prevented brittle failure modes in the infill wall.