Seismic Performance of Multi-storey Masonry Wall Repaired by Carbon Fiber Reinforced Polymer Grids

To study the failure mechanism and repair effect of plain masonry structure repaired by carbon fiber reinforced polymer (CFRP) grids, firstly, a three-storey masonry wall with openings was destroyed under the pseudo-static action, then, the areas where the cracks intensively occurred in destroyed masonry wall were repaired by CFRP grids, at last, the pseudo-static action was retested. The seismic performances of the masonry wall prior to and after repair were compared according to the lower limit of repair requirements, and the repairing suggestions were proposed. The results show that CFRP grids can effectively retard or prevent the occurrence of masonry shear diagonal cracks, and then the seismic resistance of masonry walls is developed. The lower limit of repair area is 22% when the shear bearing capacity fully restored is the indicator. The failure modes of the walls after repaired are related to the repair positions, the CFRP grids debonding and piers failure are the majority failure modes of the test. The failures initiate layer by layer from low to high, and develop from the unrepaired to the repaired zones on the same floor. The piers failure is most likely to cause the structure failure or even collapse, therefore, CFRP grids need to be preferentially applied to the piers where the shear stress is relative large, the additional strengthening measures are also essential.