Monostrand Post-Tensioning Anchor Evaluation Tests

The monostrand post-tensioning (PT) anchorage tests will focus on key variables related to self-centering wall systems: post-yield cyclic loading, PT splices, anchorage capacity after a seismic event, and durability details. Tests will be conducted prior to the shake table and wall-floor sub assemblage studies to finalize the test details. The PT anchorage system will also be investigated post-test, if needed, to analyze any unexpected phenomena observed in the large-scale tests. Two manufacturers of 7-wire monostrand anchorages will be tested under monotonic and cyclic loading procedures. Standard monostrand tests provide a baseline to compare results of previous research and to evaluate effects of post-yield cyclic loading and splices. Splices are an important part of the testing program because they are needed to tie the wall into the foundation and to extend the tendons in tall multistory structures. Splices will be investigated extensively in the monostrand tests as they are also significantly more complex in multistrand tendons. To investigate the remaining capacity of a tendon after the first major seismic event, samples from the tendons and anchorages used in the shake table tests will be tested to failure simulating loading from an aftershock or another major seismic event. Durability is a key component to any post-tensioned system. The most widely used internal unbonded PT tendon system in practice is a greased/sheathed monostrand system (PT coating with extruded plastic sheath). Unbonded internal multi‐strand systems are much less common. For the systems described in this project, details will be developed for a greased system applicable to multi‐strand PT tendons in walls.