Effects of Tendon Spacing on In-Plane Behavior of Posttensioned Masonry Walls

In-plane behavior of unbonded posttensioned clay brick masonry walls are investigated using detailed finite-element (FE) models. FE models of three walls having different aspect ratios of 1.50, 1.00, and 0.67 are developed. Effects of tendon spacing on in-plane behavior of these walls are investigated using different tendon spacings ranging from 0.61 m (2 ft) to 3.81 m (12.5 ft). In addition, the effects of having different horizontal reinforcement ratios of 0%, 0.1%, and 0.5% on the in-plane behavior of the walls were investigated. The stresses in the tendons are calculated using different approaches, and then the flexural strength of each wall is calculated and compared with those obtained from the numerical analysis. The simulation results show that for spacing between tendons up to 2 m (6.6 ft), ignoring the elongation in the tendon in calculating the flexural strength results in too conservative design. For these walls, it is more appropriate to use equations provided by the Masonry Standard Joint Committee for out-of-plane behavior of masonry walls. For spacing between tendons greater than 2 m (6.6 ft), ignoring the elongation in tendons and using the effective posttensioning force to calculate the flexural strength agree well with those obtained from the FE analyses. The FE analyses showed that adding shear reinforcement for walls with tendon spacing smaller than 2 m (6.6 ft) does not improve the shear strength of the walls. However, for walls having spacing between tendons greater than 2 m (6.6 ft), even with small amount of shear reinforcement, the shear strength increases significantly.