(4) In Figure 9, the results of the event are given for different reinforcement arrangements. All schemes except for No.19 and No.8 (not shown) cause either more damage to the masonry or produce higher locked in stresses compared with the
similar unstrengthened wall. Arrangement No.19 has marginally improved resistance and prevented any blocks from falling away from the wall. In the case of No.13, an oscillatory mechanism develops above the first storey horizontal reinforcement
causing increased damage by vertical movement.
Maximum acceleration 0.15g
Diagonal (No.7)
Vertical (No 6)
Diagonal and horizontal (No.13)
Diagonal and horizontal (No.19)
Figure 9. Diagonal, vertical, horizontal reinforcement
(contours of principal compressive stresses)
(5) Results obtained from schemes with the most developed patterns of reinforcement combining diagonal, vertical and horizontal bars are shown in Figure 10. Here, similar schemes have been applied to both the plain wall and the wall with
openings. It is similar to No.19 except that the bottom horizontal reinforcement lies in the bottom course of blocks. This helps eliminate vertical motion caused by rocking of the blocks below the reinforcement level. The plain wall remains intact
throughout the seismic event with the reinforcement controlling the development of cracking. Even under 0.3g loading, although higher locked in stresses are predicted little damage is evident. Without reinforcement, blocks left unsupported rapidly
propagate failure mechanisms leading to collapse.
