360R-06
Design of Slabs-on-Ground
2006, 74 pp.
$95.50

This document presents information on the design of slabs-on-ground, primarily industrial floors. The report addresses the planning, design, and detailing of slabs. Background information on design theories is followed by discussion of the types of slabs, soil-support systems, loadings, and jointing. Design methods are given for unreinforced concrete, reinforced concrete, shrinkage-compensating concrete, post-tensioned concrete, fiber-reinforced concrete slabs-on-ground, and slabs-on-ground in refrigerated buildings, followed by information on shrinkage and curling problems. Advantages and disadvantages of each of these slab designs are provided, including the ability of some slab designs to minimize cracking and curling more than others. Even with the best slab designs and proper construction, however, it is unrealistic to expect crack-free and curl-free floors. Consequently, every owner should be advised by both the designer and contractor that it is normal to expect some amount of cracking and curling on every project, and that such occurrence does not necessarily reflect adversely on either the adequacy of the floor’s design or the quality of its construction. Design examples appear in an appendix.

Keywords: concrete; curling; design; floors-on-ground; grade floors;industrial floors; joints; load types; post-tensioned concrete; reinforcement(steel, fibers); shrinkage; shrinkage-compensating; slabs; slabs-on-ground;soil mechanics; shrinkage; warping.

Contents: Contents:

Chapter 1—Introduction, p. 360R-3

1.1—Purpose and scope

1.2—Work of Committee 360 and other relevant committees

1.3—Work of non-ACI organizations

1.4—Design theories for slabs-on-ground

1.5—Overview of subsequent chapters

1.6—Further research

Chapter 2—Slab types, p. 360R-5

2.1 — Introduction

2.2 — Slab types

2.3—General comparison of slab types

2.4—Design and construction variables

2.5—Conclusion

Chapter 3—Support systems for slabs-on-ground,

p. 360R-7

3.1—Introduction

3.2—Geotechnical engineering reports

3.3—Subgrade classification

3.4—Modulus of subgrade reaction

3.5—Design of slab-support system

3.6—Site preparation

3.7—Inspection and site testing of slab support

3.8—Special slab-on-ground support problems

Chapter 4—Loads, p. 360R-17

4.1—Introduction

4.2—Vehicular loads

4.3—Concentrated loads

4.4—Distributed loads

4.5—Line and strip loads

4.6—Unusual loads

4.7—Construction loads

4.8—Environmental factors

4.9—Factors of safety

Chapter 5—Joints, p. 360R-21

5.1—Introduction

5.2—Load-transfer mechanisms

5.3—Sawcut contraction joints

5.4—Joint protection

5.5—Joint filling and sealing

Chapter 6—Design of unreinforced concrete slabs,

p. 360R-29

6.1—Introduction

6.2—Thickness design methods

6.3—Shear transfer at joints

6.4—Maximum joint spacing

Chapter 7—Design of slabs reinforced for crackwidth control, p. 360R-32

7.1—Introduction

7.2—Thickness design methods

7.3—Reinforcement for crack-width control only

7.4—Reinforcement for moment capacity

7.5—Reinforcement location

Chapter 8—Design of shrinkage-compensating

concrete slabs, p. 360R-32

8.1—Introduction

8.2—Thickness determination

8.3—Reinforcement

8.4—Other considerations

Chapter 9—Design of post-tensioned slabs-onground,

p. 360R-36

9.1—Notation

9.2—Definitions

9.3—Introduction

9.4—Applicable design procedures

9.5—Slabs post-tensioned for crack control

9.6—Industrial slabs with post-tensioned reinforcement for structural support

9.7—Residential slabs with post-tensioned reinforcement for structural action

9.8—Design for slabs on expansive soils

9.9—Design for slabs on compressible soil

Chapter 10—Fiber-reinforced concrete slabs-onground,

p. 360R-45

10.1—Introduction

10.2—Polymeric fiber reinforcement

10.3—Steel fiber reinforcement

Chapter 11—Structural slabs-on-ground

supporting building code loads, p. 360R-48

11.1—Introduction

11.2—Design considerations

Chapter 12—Design of slabs for refrigerated facilities, p. 360R-49

12.1—Introduction

12.2—Design and specification considerations

12.3—Temperature drawdown

Chapter 13—Reducing effects of slab shrinkage

and curling, p. 360R-50

13.1—Introduction

13.2—Drying and thermal shrinkage

13.3—Curling and warping

13.4—Factors that affect shrinkage and curling

13.5—Compressive strength and shrinkage

13.6—Compressive strength and abrasion resistance

13.7—Removing restraints to shrinkage

13.8—Base and vapor retarders/barriers

13.9—Distributed reinforcement to reduce curling and number of joints

13.10—Thickened edges to reduce curling

13.11—Relation between curing and curling

13.12—Warping stresses in relation to joint spacing

13.13—Warping stresses and deformation

13.14—Effect of eliminating sawcut contraction joints with post-tensioning or shrinkage-compensating concrete

13.15—Summary and conclusions

Chapter 14—References, p. 360R-57

14.1—Referenced standards and reports

14.2—Cited references

APPENDIX

Appendix 1—Design examples using PCA method,

p. 360R-61

A1.1—Introduction

A1.2—PCA thickness design for single-axle load

A1.3—PCA thickness design for slab with post loading

A1.4—Other PCA design information

Appendix 2—Slab thickness design by WRI method, p. 360R-63

A2.1—Introduction

A2.2—WRI thickness selection for single-axle wheel load

A2.3—WRI thickness selection for aisle moment due to uniform loading

Appendix 3—Design examples using COE charts,p. 360R-64

A3.1—Introduction

A3.2—Vehicle wheel loading

A3.3—Heavy forklift loading

Appendix 4—Slab design using post-tensioning,p. 360R-67

A4.1—Design example: Residential slabs on expansive soil

A4.2—Design example: Using post-tensioning to minimize cracking

A4.3—Design example: Equivalent tensile stress design

Appendix 5—Examples using shrinkagecompensating concrete, p. 360R-72

A5.1—Introduction

A5.2—Example with amount of steel and slab joint spacing predetermined

Appendix 6—Design examples for steel FRC slabs-on-ground using yield line method, p. 360R-72

A6.1—Introduction

A6.2—Assumptions/design criteria

Conversion factors, p. 360R-74