Surge Wave Loading onWood StructuresJebediah Wilson, Former Graduate Student

Rakesh Gupta, ProfessorDept. of Wood Science and Engineering

Oregon State U.

John van de Lindt, Professor and Drummond ChairDept. of Civil Engineering. U. of Alabama

Daniel T. Cox, ProfessorDept. of Civil Engineering, Oregon State U.

2010 SWST International Convention, Geneva, Switzerland

THE STORY OF THIS PROJECT STARTED AFTER HURRICANE KATRINA…………………WHERE….

Florida

Texas

New Orleans

……WE SAW THIS KIND OF DAMAGE……AND…..

……THIS KIND OF STRUCTURAL DAMAGE…….AND….

TOTAL STRUCUTRE COLLAPSE ROOF COLLAPSE

ROOF SHEATHING FAILUREPORCH COLLAPSE

.......... AND DAMAGE CAUSE BY SUEGE WAVES WHERE…

5

A HOUSE ABOUT 1 KM FROM THE COAST

…….WHOLE STRUCUTRES WERE WIPED OUT OFF THEFOUNDATION NEAR THE COAST LINE.

SURGE WAVE DAMAGE BY Asian Tsunami (2004)

http://www.geology.um.maine.edu/geodynamics/...www.waveofdestruction.org/tsunami-photos 6

SURGE WAVE………………..AND……………….DAMAGE

SURGE WAVE DAMAGE BY Hurricane Ike (12AM, 13 Sept. 2008, Galveston, TX)

HOUSTON

What damage wascausedby Hurricane Ike?

THIS IS HOW THE HOUSE SURVIVED…….BY…..

DOING WHAT THE ENGINEERS SPELLED OUT

AND

PAYING ATTENTION TO DETAILS

........................Mike Riley

So, our Question was:

What are the wave forces on woodframe buildings ?

We got NSF Funding ($75,000):

To look into: Wave Loading on Residential Structures

PI – John van de Lindt, Colorado State U.(Graduate Student – Rachel Garcia)Co-PI – Rakesh Gupta(Graduate Student – Jebediah Wilson)

Overview of Research ApproachDesign of Scale House

Testing in a Wave Basin

Full Scale Testing at CSU

Relate Test Parameters to Damage

Objectives:1. To measure forces on a 1/6th scale

wood framed structure.2. To evaluate qualitatively the

structural response to different loading conditions and structural configurations.

12

Literature ReviewCity and County of Honolulu Building Code

Gives general guidelines to design for wave loading

It deals with multiple aspects of wave forces:

Surge force FS = 4.5 ∙ ρ ∙ g ∙ h2

Some evidence indicates this code over predicts forces.

13

Literature ReviewThusyanthan and Madabhushi (2008) Model coastal Sri Lankan structures scaled at 1:25

Compared standard design to tsunami resistant design

Openings and raised house reduced loading enough to prevent structural failure (remember Mike Riley whose house survived Hurricane Ike!)

14

Literature ReviewBuilding Code in the USA (ASCE/SEI 07-05)

~ 60 pages on Wind Loading

> 100 pages (12 Chapters) on Seismic Design

5 pages on Flood Loading, only 2 pages which are specifically on Wave Loading

15

We did Initial Study in 2007 Summer

Tested 1:36 scale model

Tested by student Jason Miles

Purpose: To make recommendations for 1:6 scale tests

1:36 Scale Model

LOADCELL

LOADCELLS

Model in WAVE BASIN1:36 Scale Model

Wave Impact

Vertical Loads During Wave Impact

-10

-5

0

5

10

15

20

2.5 2.55 2.6 2.65 2.7 2.75 2.8 2.85 2.9 2.95 3

Forc

e (lb

)

Time (s)

Typical Impact Forces

Front SensorRear Right SensorRear Left Sensor

T

C

EXPECTED RESPONSE

Floor Plans For 1/6th Scale Test Structure

First Story Second Story 21

1.2 m X 2.4 m

1/6th Scale Test Structure

22

1/6th Scale Test Structure

23

1/6th Scale Test Structure

24

1/6th Scale Test Structure

25

1/6th Scale Structure in the Tsunami Wave Basin

26

Wave Lab Floor Plan and Elevation

Length: 48.8 m (160 ft)

Width: 26.5 m (87 ft)

Depth: 2.1m (7.0 ft)

27

Wave Lab Instrumentation

28

Experimental conditions tested: Increased surface area for loading Closed and open windows Elevated structure Open crawl space and closed crawlspace Varying wave magnitudes

1.0m or 1.1m water depth 10cm, 20cm, 30cm, 40cm, 50cm, 60cm wave heights

Wave Lab Tests

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Test Matrix

142 Wave Lab Trials

Wave Ht. (cm) 0-1.0-WC-F-NE 0-1.0-WO-F-NE 0-1.1-WC-F-NE10 2 0 220 2 4 430 2 0 240 4 3 450 2 0 260 3 5 2

Total → 15 12 1643 Total Trials

KEY90 = 90° Orientation0 = 0° Orientation1.0 = 1.0 m water depth1.1 = 1.1 m water depthWO = Windows open WC = Windows closedF = FlashedNF = Non-FlashedE = Elevated structureNE = Non-Elevated Structure

Wave Ht. (cm) 90-1.0-WC-F-NE 90-1.0-WO-NF-NE 90-1.1-WC-F-NE 90-1.1-WO-NF-E 90-1.1-WC-NF-E10 0 2 2 0 220 0 4 2 7 730 0 3 2 2 040 8 4 2 8 950 0 1 2 2 260 7 4 2 3 10

Other 0 0 2 0 015 18 14 22 30Total →

99 Total Trials

30

Results & Discussion

31

WAVE Action

Results & Discussion

32

Different Wave Types

Results & Discussion

33

HOUSE SMASH

Results & Discussion

40 cm Wave

House Orientation:0-1.0-WC-F-NE

34

Tension

Compression

RAW DATA – EXPECTED RESULTS

Results & Discussion

35Experimental setup was effective at measuring force

FORCE VALUES:

Results & Discussion Behavior of 1/6th Scale Structure – ELEVATED STRUCTURE

36Uplift predominant force w/ water beneath structure

Results & Discussion Behavior of 1/6th Scale Structure – NON-ELEVATED

37Expected Behavior – Overturning Moment

Results & Discussion Behavior of 1/6th Scale Structure(Windows Closed versus Windows Open)

0-1.0-WC-F-NE

0-1.0-WO-F-NE

0

500

1000

1500

2000

2500

0 10 20 30 40 50 60 70

Forc

e (N

)

Wave Height (cm)

38Force Windows Closed ~ 2.4 X Force Windows Open

Conclusions Experimental setup was effective at measuring force

Uplift predominant force w/ water beneath structure

Predominant force – Overturning Moment

Force Windows Closed ~ 2.4 X Force Windows Open

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Conclusions - Recommendations

Simplified structure - isolation of single variables

Higher repetition of trials

Better Instrumentation

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Next Step... NSF Funding.......Dan Cox & RG (OSU) / John van

de Lindt (CSU) / Francisco (TAMU-K) ($375K)

NEESR II: Reducing damage risk to coastal structures by understanding tsunami behavior around structures

- Test 12’ wide transverse walls - Test 8’ X 8’ shear walls

Testing completed……Data Analysis in Progress

FUTURE PLAN..........

Test full scale house(If we can find funding)

43

QESTIONS(RAKESH.GUPTA@OREGONSTATE.EDU)

NEAR ANKOR VAT TEMPLE IN COMBODIA

Materials and MethodsIncreased Area for Loading

44

Materials and MethodsClosed and Open Windows

0° Orientation – Flashed Baseplate – Non-Elevated Structure

Closed Windows

Open Windows

45

Materials and MethodsStructural Irregularities

90° Orientation – Windows Closed – Flashed Baseplate – Non-Elevated Structure46

Materials and MethodsElevated Structure

90° Orientation – Windows Open – Non-Flashed Baseplate – Elevated Structure47

Materials and MethodsOpen Crawlspace

90° Orientation – Windows Open – Non-Flashed Baseplate – Non-Elevated Structure48

Materials and MethodsClosed Crawlspace

90° Orientation – Windows Closed – Flashed Baseplate – Non-Elevated Structure49

Results & Discussion Behavior of 1/6th Scale Structure (O° versus 90°)

0

0.5

1

1.5

2

2.5

0 20 40 60 80Wave Height (cm)

Rat

io

Force (N/m) - 0°/90°

L/b ratio

Lb

0°

90°

Wave loading is not proportional to width of structure