fema 550 training for local building officials (icc abm...

FEMA 550 Training for Local Building Officials

(ICC ABM 2013) 1-1

FEMA 550 Training for Local Building OfficialsFEMA 550 Training for Local Building Officials

FEMA 550, Recommended Residential Construction for

Coastal Areas (December, 2009)

Introduction to Coastal Foundation Design

and Construction for Local Building Officials


Training Overview: Course Units

Unit 1: Brief on Training Background and Goals

Unit 2: Natural Hazards in a Coastal Environment and Their Affect on Coastal Foundation

Unit 3: Building Codes and Standards and Regulatory Requirements

Unit 4: Using FEMA 550 and General Discussion

1-4


Unit 1: Introduction and Course Overview


(ICC ABM 2013) 1-2


Powerful winds, high waves, and damaging storm surge

1-6

Natural Hazards in Coastal Areas


Approximately 18,000 dwelling units were rendered uninhabitable by Hurricane Opal and approximately one-fifth of the 18,000 were destroyed

1-7

Hurricane Opal (1995)


Over 100 oceanfront homes with shallow foundation systems collapsed caused by the combined effects of erosion and scour.

1-8

Hurricane Fran (1996)


(ICC ABM 2013) 1-3


Both shallow and deep foundations failed

Collapse of a 5-story building on shallow foundation

1-9

Hurricane Ivan (2004)

Pile foundation failure lacked sufficient embedment depth


� Was a 500-year event in some areas

� Compared to flood damages, wind damages were limited

1-10

Hurricane Katrina (2005)


� Destroyed 300,000 single-family homes in Louisiana and Mississippi and nearly all buildings within 1000 feet of the coast.

1-11

Hurricane Katrina (2005)

Destroyed slab foundations (Long Beach, Mississippi)


(ICC ABM 2013) 1-4


� Destroyed thousands of homes (nearly 4,000 on Bolivar Peninsula alone) and damaged thousands more

� Affected LA to TX

� Similar to Katrina (more flood damage than wind)

� Scour and erosion muchworse than Katrina

1-12

Hurricane Ike (2008)






(ICC ABM 2013) 1-5




� Made landfall in Bringantine, NJ on October 29, 2012

� Affected 24 states including entire east coast from Florida to Maine

� New Jersey and New York were hardest hit

� The National Hurricane Center estimates Sandy caused near $50 bullion of damage in the US1

Hurricane Sandy (2012)

1-16

Image Source: Wikipedia, the free encyclopedia

1 Tropical Cyclone Report Hurricane Sandy (AL182012) 22-29 October 2012


Hurricane Sandy (2012)

1-17

MAT deployed in

4 sub-teams:

• Coastal

• Hospitals and Other Critical Facilities

• High-Rise, Police, Fire, Municipal and Schools

• Historic


(ICC ABM 2013) 1-6


Recovery Advisories

1-18

Sandy MAT Recovery Advisories – Brief, focused advisories to help address key observations in a timely manner1. Improving Connections in Elevated Coastal Residential Buildings

2. Reducing Flood Effects in Critical Facilities

3. Restoring Mechanical, Electrical, and Plumbing Systems in Non-

Substantially Damaged Residential Buildings


Recovery Advisories

1-19

Sandy MAT Recovery Advisories – Brief, focused advisories to help address key observations in a timely manner4. Reducing Operational Interruptions to Mid- and High-Rise Buildings

During Floods

5. Designing for Flood Levels Above the Base Flood Elevation After

Hurricane Sandy

6. Protecting Building Fuel Supplies from Flood Damage

7. Reducing Flood Risk and Flood Insurance Premiums for Existing

Buildings

http://www.fema.gov/building-science/hurricane-sandy-building-science-activities-resources


To avoid failure, all foundations must:

� Support the structure above

� Resist gravity loads, live loads, and wind loads imposed on the structure and on the foundation

� Some must resist snow loads, seismic loads, and retained soil loads

� Be constructed in a fashion where they can perform with little or no maintenance

1-20

Building on Strong and Safe Foundations –Basic Issues for Typical Foundations


(ICC ABM 2013) 1-7


Building on Strong and Safe Foundations – Key Issues for Coastal Foundation

Coastal foundations must also

� Withstand flood loads

� Function after being undermined by scour and erosion

� Resist higher wind loads than other portions of the U.S. (typically)

1-21

FEMA 550 Training for Local Building OfficialsFEMA 550 Training for Local Building Officials 1-22

Foundation Failures – Numerous Failure Modes Observed

Erosion and Scour

South side of building was undermined and collapsed into scour hole


Foundations historically used in inland areas often fail when used in coastal areas

1-23

Foundation Failures

House with a basement foundation in Coastal A or V Zones, Ortley Beach

Piers on discrete footings undermined by scour near Ocean Avenue, Mantoloking, NJ


(ICC ABM 2013) 1-8


Foundation Failures

1-24


Foundation Failures


Foundation Failures – Buoyancy


(ICC ABM 2013) 1-9


Construction in Your Area?

Consider

� 32' x 32', two-story house (10' story height), situated away from the shoreline

� Elevated 8' above grade on 25 square timber piles (spaced 8' apart), driven into medium dense sand

� Subjected to 130-mph winds (3-second gust) wind speed and a 4' stillwater depth with storm surge and broken waves passing under the elevated house

� What do you think?


Construction in Your Area?

Shaded Areas indicate failure


What will this training course present?

� Provide background on FEMA 550

� Discuss the natural hazards unique to coastal areas

� Discuss how those hazards affect foundations

� Discuss FEMA 550 and how best to use its guidance

1-29

Overview


(ICC ABM 2013) 1-10


� Present design features and the materials and methods that improve the performance of foundations in coastal areas.

� Provide guidance for incorporating flood and high-wind mitigation best practices into the process of designing and constructing foundations.

� Familiarize the attendees with building code requirements.

1-30

Goals


Training Course Materials

� FEMA 550: Recommended

Residential Construction for the

Gulf Coast

� Student manual

� Training course evaluation form

1-31


Introductions

� Your name

� Type of work

� Geographical area

� Course expectations

1-32


(ICC ABM 2013) 1-11


Questions?

1-33


(ICC ABM 2013) 2-1

Unit 2: Natural Hazards in a Coastal

Environment


� High winds

� Floods

� Breaking waves

� Flood-borne debris

� Erosion and scour

Unit Topics

2-2


� High winds can create extreme

forces on a structure.

� Winds can cause a structure to

rack (distort), slide or overturn

or lift off its foundation.

� While not foundation related, high winds can also create

breaches in a building’s

envelope and allow water to

enter.

� Hurricanes are the basis for

design wind speeds in many

coastal areas.

High Winds

2-3


(ICC ABM 2013) 2-2


Design Wind Pressure

Design Wind Pressure

2-4

Wind Velocity Pressure

and

Pressure Coefficients


Design Wind Loads

Design Wind Loads

2-5


� ASCE/SEI 7-05 Minimum Loads for Buildings and Other

Structures

� ASCE 7-05 Referenced by Model Building Codes

� Wind Speed are 3-second

gust wind speeds for

Exposure Category C at 33 feet above ground

� 90 mph inland

� Up to 150 mph (+/-)

along coast

Basic Wind Speed Map

2-6


(ICC ABM 2013) 2-3


� Corresponds to the 3-second gust speed measured at 33 feet

(10 meters) above ground, which is the maximum 3-second gust

measured under Exposure Category C conditions (i.e., airport open terrain)

� Corresponds to a 50-year (inland) and approximately 100-year

(in coastal hurricane-prone areas) return period

2-7

Basic Wind Speed


� While designers use 3-second gust speeds, hurricanes are classified

according to Saffir-Simpson Scale (1-minute sustained). Older codes used a “fastest mile” wind speed

� For same wind intensity, the three wind speeds differ with averaging

period

Wind Speed – Averaging Period

2-8

Strength1-Minute Sustained Wind

Speed (mph) *

Fastest Mile

Wind Speed (mph)*Gust Wind Speed (mph)*

Category 1 74 - 95 75 - 99 89 - 116

Category 2 96 - 110 100 - 117 117- 134

Category 3 111 - 130 118 - 140 135 - 159

Category 4 131 - 155 141 - 169 160 - 189

Category 5 > 155 > 169 > 189

* Wind speed over open water


� Reflects the characteristics (roughness) of ground surface

irregularities

� For the same event, wind speeds across open flat areas are

greater than speeds across obstructed areas

Wind Exposure Categories

2-9


(ICC ABM 2013) 2-4


Exposure A

Heavily built-up city centers with tall

buildings (ASCE 7-05, C6.5.6).

Since the ASCE 7-02 edition, Exposure

A was deleted because the variability of

the wind (caused by local channeling and wake buffeting effect) is too great in

areas in close proximity to tall buildings.

2-10

Method 3 – Wind Tunnel Procedure

(ASCE 7-05, Chapter 6.6) is

required


Exposure B

Urban and suburban areas, wooded areas, or

other terrain with numerous, closely spaced obstructions having the size

of single-family homes or larger.

ASCE 7-05, Chapter 6

2-11


Exposure C

Open terrain with scattered obstructions

having heights generally less than 30 feet (9.1 meters). This category includes flat,

open country, grasslands, and all water

surfaces in hurricane-prone regions.


2-12


(ICC ABM 2013) 2-5


Exposure D

Flat, unobstructed areas and water surfaces

outside hurricane-prone regions. This category includes smooth mud flats, salt flats, and

unbroken ice.


2-13


Exposure Effects

2-14

The higher we are above the friction effects of the ground, the

greater the wind pressure effects are.

0

10

20

30

40

50

0 0.5 1 1.5 2

He

igh

t a

bo

ve

gro

un

d l

eve

l, z

(f

t)

Velocity Pressure Exposure Coefficient, Kz

Exposure C

Exposure D

Exposure B


Shape of topographic feature and maximum speed-up effect

Topographic Effects

2-15

Source: Davenport, A.G., Georgiou, P.M., and Surry, D. A Hurricane Wind Risk Study for the Eastern Caribbean, Jamaica and Belize with Special Consideration to the Influence of Topography. (London, Ontario, Canada: Boundary Layer Wind Tunnel Laboratory, The University of Western Ontario, 1985).


(ICC ABM 2013) 2-6


Wind Damage

2-16

Blow-off of cantilevered platform

(estimated wind speed: 120 mph)

Blow-off caused panels to

progressively fail (estimated

wind speed: 130 mph)


� Flooding is the most common natural hazard in the United States.

� Hurricanes and tropical storms are primary causes of flood inundation.

� In addition to inundation, flooding can have a variety of impacts on coastal buildings and their foundations.

2-17

Flood Hazards in Coastal Areas


Flood Damages

2-18

Buoyancy and moving floodwaters forced home off of its foundation

Open foundation damaged by flood-borne debris


(ICC ABM 2013) 2-7


Effects

� Storm surge/inundation

� Wave effects



Important Factors

� Flood zone

� Stillwater depth

� Flood-borne debris sources

� Site soils and topography

� Obstructions

Coastal Flooding Effects and Important Factors

2-19


Delineation is determined by wave height

Flood Zones in Coastal Areas

2-20


Stillwater Depth controls the height of a depth limited wave

Stillwater Depth and Wave Height

2-21

Stillwater Flood Elevation


(ICC ABM 2013) 2-8


Building Damage vs. Flood Depth

2-22


Open foundations are required in V Zones and recommended in

Coastal A Zones

�Allow floodwater to flow through foundations

�Area below home can

only be used for

parking and storage

�“Breakaway” walls

required below BFE

Open Foundations

2-23

Lowest horizontal member


Closed Foundations

� Closed foundations are prohibited in V Zones

� Are allowed (by NFIP) in all A Zones

� Are not recommended in Coastal A Zones due to the disastrous effect even small waves can have on them

2-24

Finished Floor


(ICC ABM 2013) 2-9


Breaking Waves

2-25


Wave Effects

2-26

Erosion and some non-

structural damage

Erosion and breakaway

wall damage


Flood-borne Debris

2-27

Pier pilings carried over 2 miles by the storm surge and waves

of Hurricane Opal (Pensacola Beach, Florida)


(ICC ABM 2013) 2-10


Flood-borne Debris Effects

Home turned into flood-borne debris after being dislodged from

foundation (Ortley Beach, NJ)

2-28


Scour and Erosion

� Erosion is lowering of ground surface due to moving waters � Long Term

� Storm Induced (Short Term)

� Scour is localized loss of soil when moving floodwaters meet obstructions

� Both affect foundation performance

� Erosion affects flood loads


Scour and Erosion

2-30


(ICC ABM 2013) 2-11


Scour and Erosion

FEMA 550 Training for Local Building Officials 2-32

Scour and Erosion Damage


Scour and Erosion Damage

Failure of foundation walls undermined by scour

House undermined by bluff erosion Photograph by Lesley Ewing. Courtesy of

California Coastal Commission

2-33


(ICC ABM 2013) 2-12


Long-Term Erosion

2-34


Wind

� Make homes and foundations strong enough to resist wind

loads

� Construct with strong materials fastened with adequate

connections

Flood

� Elevate homes to avoid floods

� Construct foundations strong enough to resist loads and deep

(and strong) enough to resist scour and erosion

Coastal Construction Recommendations

2-35


Best Practices Implemented


(ICC ABM 2013) 2-13


Questions?

2-37


(ICC ABM 2013) 3-1

Unit 3: Building Codes and Standards and Regulatory Requirements


� Performance design codes and standards specifically describe

the end result to be attained

Architects and Engineers develop designs to achieve the

required level of performance

� Prescriptive design codes and standards describe one method

of achieving the end results specified by performance codes and standards

Developed by consensus process

Used by builders – often without direct input from design

professionals

3-2

Building Codes and Standards


We know how to design foundations and what loads the

foundations need to resist.

Performance Codes and Standards

3-3


(ICC ABM 2013) 3-2


Most residential construction is built to prescriptive designs. IRC,

SSTD-10, WFCM, AISI Standard and are widely adopted

documents that contain prescriptive wind-resistant designs. ICC-600 issued in 2008.

However, the flood provisions in model codes and standards are

still in their infancy.

Prescriptive Codes and Standards

3-4


IRC Limitations

Section 301.2.1.1 of the IRC precludes the use of the IRC

for areas where the basic wind speed:

“…equals or exceeds 100 miles per hour (45 m/s) in

hurricane prone regions, or 110 miles per hour (49 m/s)

elsewhere….”

IRC Section 202 defines Hurricane Prone Regions as

areas along the Atlantic and Gulf of Mexico where the

basic wind speed is greater than 90 mph (and Hawaii,

Puerto Rico, Guam, Virgin Islands, and American Samoa)


Flood-Resistant Design

ASCE Standards Foundation design

examples,

foundation types and construction,

referenced fact

sheets, cost

estimating, etc.Basic Principles of Flood-Resistant

Foundation Design and Construction


(ICC ABM 2013) 3-3


� Design wind speed

� Base Flood Elevation (BFE) or Design Flood Elevation (DFE)

at the site

� Flood zones at the site

� Building layout

� Topographic elevation of

existing building site

Information can be obtained from

� NFIP

� FIS

� FIRMs or DFIRMs

� ABFEs and Flood Recovery Maps

� Local building official or

floodplain manager

Site Information

3-7


� Much of the impetus for flood-resistant design

has come through the work of the National Flood Insurance

Program (NFIP).

� NFIP was established by Congress in 1968.

� The NFIP provides the basis for the minimum requirements

included in model building codes and standards for the design and construction methods utilized to resist flood damage.

NFIP

3-8


� Special Flood Hazard Area (SFHA)

� Base Flood Elevation (BFE)

� Flood Insurance Rate Maps (FIRMs)

� Advisory Base Flood Elevations (ABFEs) and Flood Recovery Maps

Identification of Flood Hazard Areas

3-9


(ICC ABM 2013) 3-4


� The FIS contains information regarding

flooding in a community and is

developed in conjunction with the FIRM.

� The FIS, also known as a flood elevation

study, frequently contains a community's

flood history and discusses the

engineering methods used to develop

the FIRMs.

� The FIS also contains flood profiles for

studied flood sources and can be used

to determine the BFE for some areas.

Flood Insurance Study (FIS)

3-10


� Online:

� The FEMA Map Service Center:

http://www.fema.gov/hazard/map/fis.shtm

(or Google search for “FEMA MSC" and "FIS”)

� FIS tutorial: http://www.fema.gov/plan/prevent/fhm/ot_fisr.shtm(or Google search for “FEMA," "FIS," and "tutorial")

� In person:

� Local floodplain manager

� Local planning, engineering, or public works department

Finding and Using a FIS

3-11


� FIRMs are used to

determine flood insurance

rates and premiums.

� Information shown on FIRMs

affects the design and

construction requirements

for new structures,

improvement and repairs of existing structures, and

additions to existing

structures.

Flood Insurance Rate Maps (FIRMs)

3-12


(ICC ABM 2013) 3-5


For newly constructed, substantially damaged, and substantially

improved buildings

� Use open foundation

� Elevate the lowest horizontal member supporting the elevated

floor above the BFE

� Use flood-resistant materials below the BFE

3-13

NFIP Requirements in Coastal Areas


NFIP Elevation Requirements

V Zone requirements

A Zone requirements

3-14


Recommended Practices in Coastal Areas

3-15


(ICC ABM 2013) 3-6


Best Practices – V Zone Construction in Coastal A Zones

Coastal A Zone requirements

(same as V Zone requirements)

Note: FEMA Procedure Memo

50 (Dec 08): Requires Coastal

studies to delineate LiMWA (18” wave) for informational purposes


FreeboardFor most foundations, adding each foot of freeboard at the time of construction adds 0.25% to 1.0% of the at-BFE construction cost

For a V Zone example (DR = 7%, UL = 30 years), the study found it is worth spending up to:

� 3% additional to add 1 ft





Flood Insurance Savings

In V zones, flood insurance

premium savings will pay

for freeboard costs in < 5 years

In A zones, it may take

~ 5-15 years to recover

freeboard costs through

premium savings


(ICC ABM 2013) 3-7


� After a flood event, ABFEs and Flood Recovery Maps are

occasionally developed

� ABFEs incorporating post-storm conditions may be higher than

the BFEs. Special Flood Hazard Areas may extend farther

inland than existing FIRMs.

� ABFEs and Flood Recovery Maps are interim guidance recommended until new studies and mapping can be

completed.

ABFEs and Flood Recovery Maps

3-19


Questions?


(ICC ABM 2013) 4-1

Unit 4: Using FEMA 550


� Five Chapters

� Nine Appendices

FEMA 550 was developed to assemble information needed to

design residential building

foundations in coastal areas

4-2

Organization of FEMA 550


� High Winds

� Storm Surge

� Flood Effects

� Hydrostatic forces

� Hydrodynamic forces

� Waves



4-3

Chapter 1. Types of Hazards


(ICC ABM 2013) 4-2


� Foundation design criteria

� Foundation design in coastal areas

� Open and closed foundations in Special Flood Hazard Areas

(SFHAs)

� Introduction to foundation design and construction

4-4

Chapter 2. Foundations


� Wind loads

� Flood loads (DFE, stillwater depth, wave height, flood velocity)

� Hydrostatic loads

� Wave loads

� Hydrodynamic loads

� Debris impact loads

� Flood load combinations

4-5

Chapter 3. Foundation Design Loads


� Critical factors affecting foundation

design

� Wind

� Elevation

� Construction materials (e.g.,

masonry, concrete, field

preservative treatment for wood)

� Foundation design loads


� Recommended foundation types

for coastal areas

4-6

Chapter 4. Overview of Recommended Foundation Types and Construction


(ICC ABM 2013) 4-3


� Foundation design types

� Foundation design considerations

� Cost estimating

� How to use this manual

� Design examples

4-7

Chapter 5. Foundation Selection


A. Foundation Designs

B. Mississippi Pattern Book Design

C. Assumptions Used in Design

D. Foundation Analysis and Design Examples

E. Cost Estimating

F. Referenced Fact Sheets from FEMA 499

G. FEMA Publications and Additional References

H. Glossary

I. Glossary, Abbreviations, and Acronyms

4-8

Appendices


Determine

� Basic wind speed (3-second gust)

� Required foundation height above grade

� Flood zone

� Soil capacity

4-9

Using FEMA 550 - Critical Factors Affecting Foundation Design


(ICC ABM 2013) 4-4


Confirm appropriateness of selected foundation

� Flood zone and freeboard

� Foundation height

� Wind speed

� “Deep” or “shallow”

Foundation Selection

4-10


Recommended Foundation Types by Zone


� FEMA 550 designs have been developed to support homes

with a range of dimensions, weights, and roof pitches.

Building Size and Shape

4-12


(ICC ABM 2013) 4-5


Loads from Worst Case Module Used to Design Foundations

6-13


� FEMA 550 foundations are based on a rectangular module

� Modules can be assembled into different building footprints

� Similar approach to IRC, SSTD-10 and ICC-600

Modular Approach

4-14

“L” shaped “T” shaped “Z” shaped

Note: There are several ways to assemble modules.


Deep foundations

� Driven braced timber pile

� Steel pipe pile with grade beam

� Driven timber pile with grade beam

� Driven timber pile with grade & elevated concrete beam (2009)

Shallow foundations

� Grade beam foundation (2 types)

� Masonry crawl space foundation

� Masonry backfilled stem chain wall foundation

4-15

Deep and Shallow Foundations


(ICC ABM 2013) 4-6


Deep Foundation –Steel Pipe Pile with Grade Beam

� Up to 15 feet above grade

� Good for V, Coastal A, and A Zones

6 Bay Plan 9 Bay Plan


Shallow Foundation – Grade Beam

� Up to 10 feet above ground

(15 feet with integral slab)

� Good for A Zones (and Coastal A where scour and erosion is limited)

6 Bay Plan 9 Bay Plan

4-17


Securing Beam to Foundation

4-18

Foundation – Connection Details (FEMA 550)


(ICC ABM 2013) 4-7


Value Engineering (FEMA 550)

4-19


� FEMA 550 specifies minimum 1,500 psf (Appendix C).

� This applies only to shallow foundations.

� Assumed capacities of deep foundation piles are shown in Appendix A.

� For deep foundations, the number of piles will need to be adjusted based on what is achievable on the site.

FEMA 550 and Weak Soils

4-20


� Will contain designs for narrower homes

� Will contain designs for elevated reinforced concrete beams

� Allows homes constructed to ICC 600 and the IRC to be secured to the FEMA 550 foundation using prescriptive designs contained

in standards and codes

� Provides more efficient designs (reduced column sizes)

� Provides additional designs for the perimeter beams

FEMA 550 – Second Edition

5-21


(ICC ABM 2013) 4-8


FEMA 550 – Upcoming Changes

3-Bay Design for Narrow Homes

Elevated Concrete Beam Design� Smaller columns� Conventional

connections (ICC 600)


Foundation – Connection Details

From ICC-600


FEMA 550 – Moving Forward

Pre-Stressed Pile Solution-Under Consideration


(ICC ABM 2013) 4-9


Wrap-Up

5-25

� Q/A


Thank you!

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