Proof of concept investigation of unbonded reinforcement in concrete block masonry

The use of grout in conventional reinforced masonry construction increases the cost and time of construction but allows walls subject to out-of-plane loads an enhanced ability to span between lateral support levels. An experimental investigation including a total of 21 walls was conducted in an attempt to identify potential alternatives to conventionally grouted walls. The strength and serviceability of walls containing unbonded reinforcement anchored at its ends was evaluated. All walls were two and a half blocks wide and 14 courses tall and were constructed in running bond using standard 200 mm concrete blocks. Six replicate unreinforced and partially grouted, conventionally reinforced walls served as control specimens. Walls with unbonded reinforcement were determined to be inherently stable with maximum loads approaching those of partially grouted, conventionally reinforced walls. If used in practice, these walls would need to be limited to indoor exposures due to the wide crack widths that develop.

INFLUENCE OF NEAR-SURFACE MOUNTED FRP WITH CEMENTITIOUS MATERIAL ON OUT-OF-PLANE BEHAVIOR OF REINFORCED MASONRY WALLS

Eight medium scale reinforced masonry walls were built as a part of this study. These reinforced walls were strengthened using carbon fiber reinforced polymer [FRP] (bars and tapes) and glass FRP (bars) using a near surface mounted technique (NSM) with cementitious material; constant mild steel reinforcement ratio (ρ) was used. These strengthened walls were supported as a simply supported wall under an out-of-plane cyclic load applied along two line loads. This study presented the effect of different parameters, these parameters related to FRP (type and amount), bond pattern (stack and running), and existing of FRP in compression face of the walls. This paper reveals the relation between these factors and the out-of-plane capacity of the reinforced wall strengthened with FRP. Different modes of failure occurred in the strengthened reinforced walls, including a punching shear failure through the concrete block, crushing of concrete block and debonding of FRP reinforcement from the masonry substrate.