Analysis of Non-Prismatic Two-Way Post-Tensioned Slabs

Using a moment-area procedure to analyze slab-beam with step haunches, rotational stiffness, carry over, and fixed-end moments of a flat slab are formulated for flat slabs with capitals and/or drop panels. Design factors derived are represented in graphical tables and may be used in the Equivalent Frame Method (EFM) for analyzing and designing two-way post-tensioned slabs. Both of equivalent prestressing loads: a point load and/or a concentrated moment are evaluated for the stiffer column-slab conjunction region due to tensioning prestressing tendons. The results clarify this prestressing equivalent load behavior, and provide a comprehensive basis of EFM for flat slabs. Compared to a prismatic member, a stiffer column-slab joint region increases the stiffness and carryover factor, and influences fixed-end moment of slab under gravity and prestressing loads. The expressions derived for design is available both hand-calculation and computer-aided program. A calculation example is given to illustrate the use of current expressions and existing tables and chart.