Test of Scale Model Post-Tensioned Flat Plate

The testing sequence and observed behavior of a one-third scale model prestressed concrete flat plate with unbonded tendons is reported. The nine-panel model was 2.9-in. thick with 8-in. x 8-in. columns spaced 10 ft on center both directions. Draped ¼-in. diam seven-wire strands provided the prestress force with their distribution 70% in the column strip and 30% in the middle strip each direction. Bonded reinforcement was provided only in the immediate column regions where the ACI-ASCE Committee No.423 minimum, 0.15% of the column strip area, was supplied as top bars. Flexural strength and behavior was excellent and yield line analysis showed very good agreement with measured strength. Failure in shear occurred following flexural yield line development at load level above the ACI code factored load. Shear strength analysis showed the ACI-ASCE Committee equation to be safe for design of prestressed flat plates. Cracking was well controlled by the minimum bonded reinforcement. Use of the equivalent frame of ACI Code was supported for design.