COASTAL DEFENSE SYSTEMS

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The University of the West Indies Organization ofAmerican States

PROFESSIONAL DEVELOPMENT PROGRAMME:

COASTAL INFRASTRUCTURE DESIGN, CONSTRUCTION AND

MAINTENANCE

A COURSE I N

COASTAL DEFENSE SYSTEMS I

CHAPTER11

STRUCTURAL DESIGN

By DAVE BASCO, PhD

Professor, Department of Civil and Environmental Engineering

And Director, the Coastal Engineering Centre,

Old Dominion University

Norfolk, VA


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STRUCTURAL DESIGN OFSTRUCTURAL DESIGN OF

David R. Basco, Ph.D, P.E.

Director, The Coastal Engineering CenterOld Dominion University,Norfolk, Virginia

USA 23529 [email protected]


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COURSE ORGANIZATIONCOURSE ORGANIZATION

Course 2.1: Design of Coastal Structures I- Stability of loose-material structures (breakwaters and

revetments)- Case studies: Introduction, Example Problems VI-7

Course 2.2: Design of Coastal Structures II- Design philosophy; probabilistic design methods- Role of damage in coastal structure design- Cross-sectional design (breakwaters/revetments)- Balanced design prinicples

- Case study Course 4: Design of Marine Structures

- Seawalls and bulkheads- Beaches- Example problems VI-7 Armor Layer Stability


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Coastal Engineering Practice Committee

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Steven A . Hughes. Ph.D., P.E.

Coastal and Hydraulics LaboratoryUS Army Engineer Research and Development Center

David R. Basco . Ph.D., P.E.Coastal Engineering Center

Old Dominion University


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Overview of Armor Layer Stability

Rubble-Mound Trunk and Head StabilityRiprap and Toe Stability

Cross-Section Design

Example Problems

CEM Chapter VI-5-3 (Author: Hans F. Burcharth)

CEM Chapter VI-7 (Author: David R. Basco)

Based on:


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Movement of armor units

Rocking

Displacement from layer

Sliding of layer

Settlement of layer

Not armor unit breakage


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Parameter Stability Equation


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Sea State Variables Wave height

Wave length Wave steepness Wave angle Wave Asymmetry Spectrum shape Water depth Water density

Structure VariablesArmor layer slope

FreeboardArmor densityArmor gradationArmor weightArmor shape Packing density Layer thickness

Porosity of layers


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Classified by: Type of armor unit

Water depth Superstructure Dynamic Crest elevation

Non-overtopped Low-crested Submerged

Based on small-scale physical models Testing of designs is recommended

Always test unusual designs

Model Testing


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Example Problems



Based on:


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Design Guidance for These Situations


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Hudsons Equation


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where


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Example Problems



Based on:


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Gradation Range:

with


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Design guidance for: Sloping trunk and head Vertical trunk and head

Toe berms

Support main armor layer Prevent damage by scour


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Example Problems


CEM Chapter VI-7 (Author: David R. Basco)Based on:


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One Side Exposed to Waves


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Both Sides Exposed to Waves


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Geometric Design Aspects Crest elevation and width Concrete cap

Armor layer thickness Primary layer bottom elevation Toe berm Structure head

Lee-side armor Underlayers Bedding/filter layer Scour protection

Preliminary Design Phases

1. Structure geometry2. Evaluate construction

technique

3. Evaluate design materials


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Crest width:

Armor layer thickness:

Riprap layer thickness:

(whichever is greatest)


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Example Problems


CEM Chapter VI-7 (Author: David R. Basco)Based on:


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l Revetment StructureSame as runup and overtopping exmpl

The CBBT Island Case Study

l Nearshore Breakwater Structure

Chesapeake Bay Bay Ridge,MD

Cape Henry-Fort Story,VA

l Jetty Structure Oregon Inlet,NC


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Impermeable Revetment Non-overtopping Waves

Armor Stone


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CBBT original design


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October 31,1991 Northeaster The Great Halloween Storm of 1991

The Perfect Storm (Junger,1997)

The Storm of the Century (movie)


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The design wave height The evolution of design waves

Impermeable revetments

Non-overtopping waves


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Table VI-6-4 Hudson formula Table VI-6-5 Van der Meer (plunging)

Table VI-6-6 Van der Meer (surging)


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(a)Damage Curve Relations for VI-7-10 (b)Damage Curve Relations for VI-7-11

C t l E i i P ti C itt


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Nearshore breakwaters Permeable

Submerged


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SUMMARY: ARMORSUMMARY: ARMOR--LAYER STABILITYLAYER STABILITY


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SUMMARY: ARMORSUMMARY: ARMOR LAYER STABILITYLAYER STABILITY

1. Hudson (1974) SPM (1984)1. Hudson (1974) SPM (1984)

Limited applicabilityLimited applicability

-- ONLY permeable structuresONLY permeable structures

-- ONLY nonONLY non--overtopping wave conditionsovertopping wave conditions

Factors not consideredFactors not considered

-- Wave period,Wave period, TTpp-- Variable structure permeability, PVariable structure permeability, P

-- Damage level, SDamage level, S

-- Storm duration (number of waves), tStorm duration (number of waves), tdd

SUMMARY: ARMORSUMMARY: ARMOR--LAYER STABILITYLAYER STABILITY


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SUMMARY: ARMORSUMMARY: ARMOR LAYER STABILITYLAYER STABILITY

2. CEM (2000)2. CEM (2000)

No limitationsNo limitations

-- Includes wave overtopping andIncludes wave overtopping andsubmergedsubmerged condtionscondtions

-- IncludesIncludes TTpp, P, S and t, P, S and tdd factorsfactors

Methods easy for EXCELMethods easy for EXCEL

Includes partial safety factors for designIncludes partial safety factors for design

Use CEM (2000) methods to estimate armorUse CEM (2000) methods to estimate armor--

layer stability.layer stability.

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COASTAL DEFENSE SYSTEMS