Parametric study of different unbonded tendon layouts in pre-stressed concrete flat plates

Abstract

Post-tensioned unbonded tendons are widely used in fat slabs/plates when there is a demand for large span lengths, durable tendons and a reduction in the weight of structure. For post-tensioned fat slab/plates, diferent tendon layouts have been discussed in the literature. It is vital to compare the structural response (i.e., defection and stresses) and the clashing of tendons of the proposed tendon layouts in the literature to select an appropriate layout. Hence, this study focuses on the analysis of three diferent six-panel fat plates (i.e., panel sizes: 6 m×6 m, 9 m×6 m and 11 m×6 m) with fve diferent tendon layouts, using computer programs ADAPT-Floor Pro and FEM-Design 17, based on linear fnite element (FE) analysis. Short-term/long-term defection and stress due to service load obtained from the computer programs has also been compared, to highlight the diferences. Ultimate bending moment of resistance was calculated theoretically for diferent layouts and compared. Results from the analysis show that, when a higher portion of tendons is concentrated instead of distributed, stresses caused by other structural loads are counteracted best. The layout with all tendons concentrated also has the best results in terms of defections