Scope and Limitation

This document provides recommendations to the licensed design professionals (LDPs), contractors, architects, and owners to better understand the causes of restraint cracks; how to mitigate, detail, and evaluate restraint effects; how to repair cracks; how to calculate shortening using various methods; and how to consider restraint effects using the finite element method.

The document is directed primarily to the application of post-tensioning in building construction above or below ground. It is applicable to all building types such as commercial, residential, and mixed-use buildings, parking structures, and subterranean structures. A subterranean structure is one in which one or several posttensioned concrete decks partially or totally below grade support a superstructure built of wood, concrete, or steel construction.

The structure of the document is as follows: Section 2—causes and categorization of cracks; Section 3—crack mitigation philosophy and strategies; Section 4—crack mitigation detailing; Section 5—structural evaluation and repair of cracks; Section 6—computation of shortening movement; Section 7—shortening considerations in finite element analysis; Section 8—conclusions and recommendations; and lastly, References.

This document is not intended to be a standard or a guide. Volume change and restraint effects are specific to every project. This document is limited to the consideration of restraint to shortening cracks, all other cracks due to structural deficiencies, poor construction, mass concrete and so on, are excluded.