Out-of-plane performance of partially grouted reinforced concrete masonry walls under simulated seismic loading.
Thesis DisciplineCivil Engineering
Degree GrantorUniversity of Canterbury
Degree NameMaster of Engineering
This research project is part of a program reviewing the current masonry code NZS 4229: 1986. It involved testing two full-size partially grouted reinforced concrete masonry walls with openings subjected to simulated out-of-plane seismic loading. Theoretical studies were also carried out. The first specimen was C shaped in plan, 904m long, 204m high, with 1.8m long return walls at each end, and there were two doorway openings, one at each end of the main wall. The second specimen plan was the same as the first one, except that there was one door, one middle window and one comer window.. The walls were founded on the Ribraft floors; and were constructed using standard 20 series concrete blocks, with vertical reinforcement D12 at 800mm centres and 2D16 laid horizontally in the top two courses acted as a bond beam. The amount of reinforcement is the minimum requirement in the current masonry code NZS 4229: 1986. Only the cells containing reinforcement were grouted. The test results showed that both of the specimens exhibited a ductile behaviour with a "pinched" shape of the hysteresis response, and the load carrying capacities did not decrease even at the end of tests. The walls were capable of undergoing large amount of inelastic deformation without collapse. The ultimate loads were 5.4kPa and 6.6kPa for specimen 1 and 2, which were defined using the codified deflection limit of 2% story drift in the current loading code NZS 4203: 1992. The location and size of the openings influence the load resistance significantly. Mortar strength does not reduce the failure load, but it has a significant effect on the cracking load. Yield line theory can reasonably predict the out-of-plane strength of partially grouted reinforced concrete masonry wall, and it gives a conservative prediction. The experimental and theoretical studies suggest that the current masonry code NZS 4229: 1986 implies some degree of conservatism in application to the use of the partially grouted reinforced masonry structure.