Restraint Effectiveness in Unbonded Tendons for Prestressed Masonry

Currently, the Masonry Standards Joint Committee (MSJC) does not provide any guidance on the design of intermittent restraint systems. Post-tensioned masonry is most cost-effective when the amount of restraint necessary to provide adequate performance is minimized. This paper presents an analytical approach to determining the force transferred between the restraint and the tendon. In addition, experimental results of component testing on restraints are presented. Specimens tested include restraints formed by filling cells with mortar and grout as well as the use of a bar positioner. Analytical methods to predict the restraint capacity are also presented and compared with the results of the component testing. Finally, design provisions are suggested along with a design example problem.