2.5 : Posttensioned Masonry Walls

Post-tensioned masonry walls use high-strength steel rods or flexible tendons to enhance the strength and efficiency of masonry structures. These elements are securely anchored to the foundation and extend vertically either within the cores of the masonry units or between the masonry wythes. The construction process involves building the wall with these tensioning elements in place and allowing the mortar to fully cure.

Following the curing process, the tensioning begins. Steel rods are tensioned by tightening nuts against steel plates positioned at the top of the wall. For flexible tendons, tensioning is achieved through the use of specialized hydraulic jacks that stretch the tendons tightly, and they are subsequently anchored using steel chucks that grip the tendon wires. This method of tensioning imparts a significant vertical compressive prestress to the wall, greatly surpassing the stresses that would be induced by the wall’s self-weight and any external loads.

The application of such compressive prestress is crucial as it enhances the wall’s resistance to tensile forces, which are typically induced by environmental factors like wind and seismic activity. By enabling the use of thinner wall structures with fewer grouted cores, post-tensioned masonry not only conserves materials but also reduces labor costs and increases available interior space, making it a cost-effective and structurally advantageous option in modern construction.