ACI PRC-421.2-21: Seismic Design of Punching Shear Reinforcement in Flat Plates - Guide

Description

During an earthquake, moments transferred at flat plate-column connections can produce significant shear stresses that increase their vulnerability to brittle punching shear failure. This guide provides recommendations for designing flat plate-column connections with sufficient ductility to withstand reversals of lateral drift without punching shear failure or loss of moment transfer capacity. Reinforced concrete flat plates with or without post-tensioning are discussed in this guide.

Keywords:

ductility; flat plate; post-tensioning; punching shear; seismic design; shear reinforcement; shear stud reinforcement.

Document Details

Author: Joint ACI-ASCE Committee 421

Publication Year: 2021

Pages: 36

ISBN: 9781641951524

Formats: Protected PDF/Web View

Table of Contents

CHAPTER 1—INTRODUCTION AND SCOPE, p. 2

1.1—General, p. 2

1.2—Scope, p. 2

CHAPTER 2—NOTATION AND DEFINITIONS, p. 3

2.1—Notation, p. 3

2.2—Definitions, p. 4

CHAPTER 3—LATERAL STORY DRIFT, p. 5

3.1—Lateral-force-resisting systems, p. 5

3.2—Limits on story drift ratio, p. 5

3.3—Effects of gravity loads on story drift capacity, p. 5

3.4—Design recommendations for flat plates with and without shear reinforcement, p. 7

CHAPTER 4—MINIMUM SHEAR AND INTEGRITY REINFORCEMENTS IN FLAT PLATES, p. 7

CHAPTER 5—ASSESSMENT OF DUCTILITY, p. 8

CHAPTER 6—DESIGN MOMENT TRANSFERRED BETWEEN SLAB AND COLUMN, p. 9

6.1—Frame analysis, p. 9

6.2—Simplified elastic analysis, p. 10

6.3—Probable flexural strength, p. 11

CHAPTER 7—DESIGN OF SHEAR REINFORCEMENT, p. 12

7.1—Strength design, p. 12

7.2—Summary of design steps, p. 12

7.3—ACI 318 provisions, p. 12

7.4—Safety in seismic design, p. 12

CHAPTER 8—POST-TENSIONED FLAT PLATES, p. 14

8.1—General, p. 14

8.2—Sign convention, p. 14

8.3—Post-tensioning effects, p. 14

8.4—Effective compressive stress fpc, p. 16

8.5—Extension of punching shear design procedure to post-tensioned flat plates, p. 17

8.6—Research on post-tensioned flat plates, p. 18

CHAPTER 9—REFERENCES, p. 18

Authored documents, p. 19

APPENDIX A—VERIFICATION OF PROPOSED MINIMUM AMOUNT OF SHEAR REINFORCEMENT FOR EARTHQUAKE-RESISTANT FLAT PLATE COLUMN CONNECTIONS, p. 21

APPENDIX B—VERIFICATION OF REDUCED Msc VALUE PERMITTED IN PUNCHING SHEAR DESIGN, p. 22

APPENDIX C—NOTES ON PROPERTIES OF SHEAR CRITICAL SECTION, p. 25

C.1—Equations for Jx and Jy, p. 25

C.2—Equations for γv, p. 25

APPENDIX D—DESIGN EXAMPLES, p. 26

D.1—General, p. 26

D.2—Example 1: Interior flat plate-column connection, p. 26

D.3—Example 2: Edge flat plate-column connection, p. 27

D.4—Example 3: Corner flat plate-column connection, p. 28

D.5—Example 4: Use of stirrups—interior flat plate column connection, p. 29

D.6—Example 5: Interior flat plate-column connection of Example 1, repeated using SI units, p. 30

D.7—Post-tensioned flat plate structure, p. 31

D.8—Example 6: Post-tensioned flat plate connection with interior column, p. 32

D.9—Example 7: Post-tensioned flat plate connection with edge column, p. 33

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