FPA-SC-14-0 Comments on the Post-Tensioning Institute's 'Design of Post-Tensioned Slabs-on-Ground' 3rd Edition 28 Jun 06 Issued for Website Publication Foundation Performance Association - Structural Committee Page 2 of 48 PREFACE This document was written by the Structural Committee and has been peer reviewed by the. In design examples they have covered all types of structures where PT is used including Seismic Diaphragm, Slabs on Grade and External Post-Tensioning. The reasons for cracking, spalling, and blowout and their solutions have been discussed in detail. Oct 21, 2017 In design examples they have covered all types of structures where PT is used including Seismic Diaphragm, Slabs on Grade and External Post-Tensioning. The reasons for cracking, spalling, and blowout and their solutions have been discussed in detail.