423.10R-16 Guide to Estimating Prestress Losses

423.10R-16 Guide to Estimating Prestress Losses

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Description

This guide is intended for estimation of prestress losses in concrete structures. Methods presented include lump sum, simplified approaches addressing individual source of loss, and additional estimation methods. They address losses in pretensioned and post-tensioned members, including bonded, unbonded, and external tendons. Note that these estimation methods have not been evaluated for relative merits. A discussion of the variability of prestress losses caused by the variability in concrete properties is also presented. Several example problems are included.

Keywords: creep; friction; post-tensioning; prestress loss; prestressed concrete; relaxation; shrinkage.

Document Details

Author: Joint ACI-ASCE Committee 423

Publication Year: 2016

Pages: 64.00

ISBN: 9781945487132

Categories: Prestressed Concrete

Formats: Printed Document, PDF, ePub, or Kindle

Table of Contents

CHAPTER 1—INTRODUCTION

1.1—Introduction

1.2—Scope

1.3—Historical development

1.4—Guide organization and use

CHAPTER 2—NOTATION AND DEFINITIONS

2.1—Notation

2.2—Definitions

CHAPTER 3—LUMP-SUM METHOD

3.1—Scope

3.2—Historical code requirements

3.3—Industry practice

3.4—Measured losses

CHAPTER 4—INITIAL LOSSES

4.1—Scope

4.2—Pretensioning losses before transfer

4.3—Elastic shortening losses in pretensioned members

4.4—Post-tensioning losses during tensioning and transfer

4.5—Elastic shortening loss in post-tensioned members

4.6—Elastic gain under superimposed loads

CHAPTER 5—LONG-TERM LOSSES: SIMPLIFIED METHOD

5.1—Scope

5.2—Creep of concrete (∆fpCR)

5.3—Concrete shrinkage (∆fpSH)

5.5—AASHTO LRFD approximate estimate of time-dependent losses

CHAPTER 6—LONG-TERM LOSSES: DETAILED METHODS

6.1—Scope

6.2—Creep and shrinkage models

6.3—Age-adjusted effective modulus approaches

6.4—Incremental time-step method

6.5—Computer programs

6.6—Effects of deck temperature during casting of composite deck or topping

CHAPTER 7—VARIABILITY OF LOSS CALCULATIONS

7.1—Objective

7.2—Scope

7.3—Contributions to prestress loss

7.4—Modulus of elasticity

7.5—Creep

7.6—Variational analysis

7.7—Shrinkage case study

7.8—Self-consolidating concrete

7.9—Conclusions

CHAPTER 8—EXAMPLES

8.1—Pretensioned double-tee beam

8.2—Post-tensioned slab with unbonded tendons

8.3—Post-tensioned beam with bonded tendons

8.4—Example with heat of hydration during casting

CHAPTER 9—REFERENCES

Authored documents

ERRATA INFO

Any applicable errata are included with individual documents at the time of purchase. Errata are not included for collections or sets of documents such as the Manual of Concrete Practice (MCP). For a listing of and access to all product errata, visit the Errata page.

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