Experimental study of seismic behaviour of renovated masonry structures after removing walls and seismic retrofitting

Structural renovation is an economic choice to expand space of existing masonry buildings. To this end, removing bearing walls and seismic strengthening are required in engineering practice in seismic-prone areas. Therefore, in the paper three 1/2-scale two-bay two-storey planar masonry structures, consisting of one original structure and two structures with proposed renovation schemes, were fabricated and tested under cyclic loading. The original structure consisted of brick masonry units, ring beams, and tie-columns. The first renovated structure was designed by removing two bearing walls at the ground storey, adding two short-width shear walls, and enlarging the beam sections. The second renovated structure was achieved by removing one wall in the ground storey, enlarging the sections of confined beams and columns to form a single-bay frame, and retrofitting the adjacent wall with reinforcement layers and polymer mortar. Results indicate that all three specimens demonstrated hysteretic behaviour with pinching phenomenon. Energy dissipation capacity of the two renovated structures were both higher than that of the original structure prior to 1% drift, in particular for the first renovation scheme. In comparison, the second renovation scheme more evidently improved structural resistance, but it made the ultimate deformation capacity smaller than the original structure because the stiffness of the renovated ground story much larger than that of the second story resulted in failure concentration at the 2nd floor. Thus, it is more economic to make the lateral stiffness of the two storeys compatible during the design of renovation and strengthening. •Two schemes proposed for renovating multi-storey and multi-span masonry structures.•Half scaled two-storey two-bay masonry structures firstly tested under cyclic load.•All the specimens showing pinching hysteretic behaviour with similar peak capacity.•Renovation schemes improving energy dissipation capacity prior to drift of 1.0%.•Over-stiffened renovated ground story causing failure concentration at upper story.