ASCE Standard SEI/ASCE 24-98 Flood Resistant Design and Construction

CONTENTS

Page

STANDARDS iii

FOREWORD v

DEDICATION vii

ACKNOWLEDGMENTS ix

1.0 General 1

1.1 Scope 1

1.2 Definitions 1

1.3 Identification of Flood Hazard Areas 6

1.4 Loads in Flood Hazard Areas 6

1.4.1 General 6

1.4.2 Combination of Loads 6

1.5 Identification of Floodprone Structures 6

1.5.1 General 6

1.5.2 Consideration for Hood Protective Works 6

1.6 Classification of Structures 7

2.0 Basic Requirements for Flood Hazard Areas 7

2.1 Scope 7

2.2 General 7

2.3 Siting 8

2.3.1 Siting in Flood Hazard Areas 8

2.3.2 Siting in Floodways 8

2.3.3 Siting in High Risk Flood Hazard Areas 8

2.4 Elevation Requirements 8

2.4.1 Flood Hazard Areas Not Subject to High Velocity Wave Action 8

2.4.2 Flood Hazard Areas Subject to High Velocity Wave Action 8

2.5 Foundation Requirements 8

2.5.1 Geotechnical Considerations 8

2.5.2 Foundation Depth 9

2.5.3 Use of Fill 9

2.5.3.1 Structural Fill 9

2.5.3.2 Non-Structural Fill 9

2.5.4 Use of Load Bearing Walls 9

2.5.4.1 Required Openings in Load Bearing Foundation Walls 9

2.5.4.2 Openings in Breakaway Walls 9

2.5.5 Use of Piers, Posts, Columns, or Piles 9

2.6 Enclosures Below the Design Flood Elevation 10

2.6.1 Openings in Enclosures Below the Design Flood Elevation 10

2.6.1.1 Non-Engineered Openings in Enclosures Below the Design Flood Elevation 10

2.6.1.2 Engineered Openings in Enclosures Below the Design Flood Elevation 10

3.0 High Risk Flood Hazard Areas 11

3.1 Scope 11

3.2 Alluvial Fan Areas 11

3.2.1 Protective Works in Alluvial Fan Areas 11

3.3 Flash Flood Areas 11

3.3.1 Protective Works in Flash Flood Areas 11

3.4 Mudslide Areas 11

3.4.1 Protective Works in Mudslide Areas 12

3.5 Erosion Prone Areas 12

3.5.1 Protective Works in Erosion Prone Areas 12

3.6 High Velocity Flow Areas 12

3.6.1 Protective Works in High Velocity Flow Areas 12

3.7 High Velocity Wave Action Areas 12

3.8 Icejam and Debris Areas 12

3.8.1 Protective Works in Icejam and Debris Areas 12

4.0 Flood Hazard Areas Subject to High Velocity Wave Action 12

4.1 Scope 12

4.1.1 Identification of Areas Subject to High Velocity Wave Action 13

4.2 General 13

4.3 Siting 13

4.4 Elevation Requirements 13

4.5 Foundation Requirements 13

4.5.1 General 13

4.5.2 Special Geotechnical Considerations 15

4.5.3 Foundation Depth 15

4.5.4 Use of Fill 15

4.5.5 Pile Foundations 15

4.5.5.1 Piles Terminating in Caps at or Below Grade 15

4.5.5.2 Piles Extending to Superstructure (Structure Framing) 16

4.5.5.3 Wood Piles 16

4.5.5.4 Steel H Piles 16

4.5.5.5 Concrete-Filled Steel Pipe Piles and Shells 16

4.5.5.6 Prestressed Concrete Piles 16

4.5.6 Columns 16

4.5.6.1 Wood Posts 16

4.5.6.2 Reinforced Masonry Columns 16

4.5.6.3 Reinforced Concrete Columns 16

4.5.7 Grade Beams 16

4.5.8 Bracing 17

4.6 Enclosed Areas Below Design Flood Elevation 17

4.6.1 Breakaway Walls 17

4.7 Erosion Control Structures 17

4.8 Decks, Concrete Pads, and Patios 17

5.0 Design 18

5.1 General 18

5.2 Vertical Structural Systems 18

5.2.1 Masonry Walls 18

5.2.2 Concrete Walls 18

5.2.3 Lateral Resistance of Open Foundation Systems 18

5.2.4 Piles 18

5.2.4.1 General 18

5.2.4.2 Timber Piles 18

5.2.4.3 Steel HP-Section Piles 18

5.2.4.4 Concrete-Filled Steel Pipe Piles and Shells 18

5.2.4.5 Precast (Including Prestressed) Concrete Piles 18

5.2.4.6 Cast-in-Place Concrete Piles 18

5.2.4.7 Pile Capacity 18

5.2.4.8 Capacity of the Supporting Soils 19

5.2.4.9 Minimum Penetration 19

5.2.4.10 Foundation Pile Spacing 19

5.2.4.11 Pile Caps 19

5.2.4.12 Timber Pile Connections 19

5.2.4.13 Timber Piles Not in Tension 19

5.2.4.14 Timber Piles in Tension 19

5.2.4.15 Steel Piles Not in Tension 19

5.2.4.16 Steel Piles in Tension 19

5.2.4.17 Concrete Piles Not in Tension 20

5.2.4.18 Concrete Piles in Tension 20

5.2.4.19 Pile Splicing 20

5.2.4.20 Mixed Types of Piling and Multiple Types of Installation Methodology 20

5.2.5 Posts, Piers, and Columns 20

5.2.5.1 Application 20

5.2.5.2 Reinforced Concrete and Masonry Columns 20

5.3 Footings 20

5.4 Mats, Rafts, and Slabs 20

5.5 Grade Beams 20

5.6 Anchorage/Connections 20

6.0 Materials 21

6.1 General 21

6.2 Specific Materials Requirements for Flood Hazard Areas 21

6.2.1 Metal Connectors and Fasteners 21

6.2.2 Structural Steel 21

6.2.2.1 Corrosive Environments 21

6.2.2.2 Non-Corrosive Environments 21

6.2.3 Concrete 22

6.2.4 Masonry 22

6.2.5 Wood and Timber 22

6.2.6 Finishes 22

7.0 Dry and Wet Floodproofing 22

7.1 Scope 22

7.2 Dry Floodproofing 22

7.2.1 Dry Floodproofing Restrictions 22

7.2.2 Dry Floodproofing Requirements 23

7.3 Wet Floodproofing 23

7.3.1 Wet Floodproofing Restrictions 23

7.4 Active Floodproofing 23

8.0 Utilities 23

8.1 General 23

8.2 Electrical 24

8.2.1 Service Conduits and Cables 24

8.2.2 Exposed Conduits and Cables 24

8.2.3 Electric Meters 24

8.2.4 Disconnect Switches and Circuit Breakers 24

8.2.5 Electric Elements Installed Below Minimum Elevations 24

8.3 Plumbing 25

8.3.1 Buried Plumbing Systems 25

8.3.2 Exposed Plumbing Systems 25

8.3.3 Plumbing Systems Installed Below Minimum Elevations 25

8.3.4 Sanitary Systems 25

8.4 Mechanical, Heating, Ventilation, and Air Conditioning 25

8.4.1 Fuel Storage Tanks 25

8.5 Elevators 26

9.0 Means of Egress 26

9.1 General 26

9.2 Stairs and Ramps 26

10.0 Accessory Structures 26

10.1 General 26

10.2 Decks, Porches, and Patios 26

10.3 Garages 27

10.3.1 Garages Attached to Structures 27

10.3.2 Detached Garages 27

10.4 Chimneys and Fireplaces 27

11.0 References 27

Commentary

C1.0 General 29

C2.0 Basic Requirements for Flood Hazard Areas 33

C3.0 High Risk Flood Hazard Areas 37

C4.0 Flood Hazard Areas Subject to High Velocity Wave Action 40

C5.0 Design 46

C6.0 Materials 47

C7.0 Dry and Wet Floodproofing 48

C8.0 Utilities 49

C9.0 Means of Egress 50

C10.0 Accessory Structures 50

C11.0 References 51

Index 55