Frictional and anchorage slip losses are observed in post-tensioned members.

Explanation:

Post-tensioned members are structural elements that are strengthened by the application of tensioned steel tendons. These tendons are typically comprised of high-strength steel wires or strands that are inserted into ducts or sleeves cast into the member. Once the member has been cast and cured, the tendons are tensioned using hydraulic jacks, and then the tension is transferred to the concrete through anchorage devices.

Frictional and anchorage slip losses occur during the tensioning and transferring of the tendon forces to the concrete. These losses are factors that reduce the effectiveness of the applied prestressing force, resulting in a decrease in the member's overall strength and stiffness.

Frictional losses occur due to the resistance encountered by the tendons as they are being tensioned and pulled through the ducts or sleeves. This resistance is mainly caused by the friction between the tendons and the inner surfaces of the ducts or sleeves. Frictional losses depend on factors such as the surface condition of the tendons, the duct material, the tendon diameter, and the length of the tendon.

Anchorage slip losses, on the other hand, occur at the anchorage devices where the tendon forces are transferred to the concrete. These losses are caused by the relative movement between the tendon and the anchorage system. Anchorage slip can occur due to several reasons, including inadequate bond between the tendon and the grout or concrete, inadequate seating of the tendon in the anchorage device, or inadequate design or construction of the anchorage system itself.

Both frictional and anchorage slip losses can significantly affect the performance and behavior of post-tensioned members. These losses reduce the effective prestressing force in the member, leading to a decrease in its load-carrying capacity and an increase in its deflection and deformation. Therefore, it is essential to consider and account for these losses in the design and analysis of post-tensioned members to ensure their structural integrity and performance.

In summary, frictional and anchorage slip losses are observed in post-tensioned members due to the resistance encountered during the tensioning and transferring of tendon forces. These losses can have a significant impact on the member's strength, stiffness, and overall performance.