IFRC SRU SD TUe Engineering Humanitarian Steel

Engineering humanitarian steel (vs. best practice)

Roel Gijsbers TU/e Shelter Research Group

Introduction After the symposium Innovative Shelter 21-23 Nov 2007, the Shelter Research Group (SRG) was formed as a part of TU/e, faculty of the Built Environment.

The objective is to actively support the humanitarian aid movement with innovative solutions for post-disaster post disaster sheltering sheltering.

DEMAND SUPPLY

Private sector The SRG consists of members with different backgrounds and interests which include product development, building technology, building physics, structural engineering, impact measurement and includes also a staff member of the Netherlands Red Cross.

All members are academia and have a wide network within the industry. /Shelter Research Group

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Contents I.

Engineering methods (roughly to detailed) 1.

2.

3.

4.

II.

Intuition Rules of thumb Basic Calculation Detailed calculation

Vital structural aspects 1.

2.

3.

4.

5.

Material quality Stability Connection stiffness Foundation Risk estimation and hazard resistance

III. Engineering g g examples p 1.

2.

3.

Pakistan: transitional steel frame shelter + Parametric core shelter design + Mapping of wind & snow loading Haiti: 2 storey y family y shelter Collective Centre

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Engineering methods 1. Intuition a) Tradition b) Professional experience

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Engineering methods 2. Rules of thumb

Structural element

Section and top view

Profile size

Span

Ratio

d

Single layer

d [mm]

l [m]

profile or tube steel Wide p

100-500

6-14

20-30

Profile steel

200-1000

6-40

18-26

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l

Engineering methods 3.

Basic calculations − By ‘hand’ − Basic modeling

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Engineering methods 3.

Detailed calculations − (3D) Computer modeling − Detailed insight in performance of structural parts

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Vital engineering aspects 1.

2.

3.

4.

5 5.

Material quality Stability Connection stiffness Foundation Risk estimation and hazard resistance

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Vital engineering aspects 1. Material quality â—?

-

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Structural steel St d di d quality Standardized lit Hot rolled / cold formed Tensile strength / Yield strength s235 / s275 / s355 (and higher) Available profiles

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Vital engineering aspects 2. Stability ● ● ● ●

Excessive deformation leads to unsafe situations Stiff planes: l b bracing i / rigid i id connections ti Stability in every plane: x/y/z 2nd order effects: loads on already deformed structure

Rigid connections

Bracing /Shelter Research Group

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Vital engineering aspects 3. Connection Stiffness ● ● -

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Rotational capacity F Free (hinge) (hi ) Flexible Rigid Strength of joint itself Material quality Production quality

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Vital engineering aspects 4. Foundation All forces are transferred to the foundation! ● S il characteristics Soil h t i ti − Soil type − Groundwater table − Vegetation − Site history ● Direction and magnitude of forces ● Available materials

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Type yp and size of foundation

Vital engineering aspects Foundations resisting uplift forces: Deep and/or heavy footings

wind

1. adequate depth and mass of foundations to resist uplift 2. pile foundations in soft ground with adequate shear friction resistance to prevent pile being pulled out of the ground

Vital engineering aspects 5. Risk estimation and hazard resistance ● ● ● ● ●

Basic assumptions for structural safety calculations Shelter Lifespan (1, 5, 10, 25, 50 years?)

Return period of hazards Magnitude of loadings Financial constraints

Wh t llevell off risk What i k iis acceptable? t bl ?

Which standards are applicable?

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Vital engineering aspects Risk: Coping with Nature

Disaster magnitude versus Ri k off exceedence Risk d

Natural hazards • Geophysical • Meteorological • Hydrological • Climatological

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WORLD MAP OF NATURAL HAZARDS

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Vital engineering aspects Natural catastrophes worldwide 1980-2009

Source: Munich Re, 2010

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Ri k iis increasing!

Risk i i !

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Engineering issues for shelters • Lack of appropriate structural norms and calculation methods for humanitarian sheltering • •

Local or continental building codes are based on regular and permanent buildings Current standards for sheltering provide no clear information

• Undefined risk profile • Undefined U d fi d or unknown k level l l off hazardous h d and d extreme t loads l d to t b be expected t d • Underestimation of applied loadings leading to unsafe solutions (intuition) • Overestimation of applied loadings, loadings leading to economic disadvantage • Unknown material quality of locally available steel • Unknown production quality of locally produced components • Unknown construction quality of a locally assembled (self help) shelter p in the field to jjudge g safety y and reliability y of • Lack of structural expertise solutions within a specific context /Shelter Research Group

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EXAMPLES • Pakistan: Transitional Steel Frame Shelter  Parametric steel core shelter frame

• Haiti: 2 storey y family y shelter • Collective Center

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Pakistan: transitional steel frame shelter Parallel Prototyping Winterized family shelter Design specifications: • Dimensions: 6 x 4 x 3 m • Structural calculations with boundary conditions:  Wind Wi d speed d = 31 m/s / (112 km/h) k /h)  Snow load = 300 mm (loose snow) • Self assembly

First Pakistan prototype

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Pakistan: transitional steel frame shelter Structural Characteristics Pakistan • Bracing only in walls • Welding of parts to create roof trusses • Bolting of elements

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Pakistan: transitional steel frame shelter Structural Characteristics TU/e • Braced in all planes (cables and turnbuckles) • Unknown quality of local welding (wintertime temperature fluctuation  cracks) • Connection by bolts and nuts

• Modular interchangeable elements

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Pakistan: transitional steel frame shelter Parallel Prototyping Pakistan • Experience p based design g • Member size 18x18x0.9 mm • Total weight 80kg • Calculations missing!!! g • Upgraded tent •

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TU/e • Evidence based design g • Member size 40x40x3 mm • Total weight: 400 kg • No roof overhang g • Storm proof dwelling

Pakistan: transitional steel frame shelter TU/e Conclusions • • • • •

Pakistan prototype seems to be too light dimensioned Concept of plates, bolts and nuts works Local production of parts (if material quality is guaranteed) Flat package in transportation Concept is easy to setup

Optimization needed because of the heavy weight and worldwide applicability • Loading classes based on local situation • Column height 2000mm1800mm • Shelter size 6x4m 4x4m

Parametric core shelter design

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Parametric core shelter design Development characteristics • Core shelter: 25y lifespan • Weight optimization • Modular system: self assembly • Worldwide application • System variants for loading zones • Wind loading • Snow loading

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Parametric core shelter design Snow loading zones • Not a hazardous load load, but a largely predictable load Transitional Shelter standards: The e Netherlands: et e a ds

30 kg/m2 (±15 cm of snow) 70 0 kg/m g/ 2 ((x 0 0.8 8 = 56 kg/m g/ 2)

• Based on values in Eurocode & academic research • Applicable up to 1500m above sea level

Snow zone S0 S1 S2 S3 S3

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Snow load 2 ((kN/m / ) 0 0 ‐ 0,5 0.5 ‐ 1.0 1 0 1.5 1.0 ‐ 15

Parametric core shelter design Wind loading zones • •

Basic wind speed Averaging time (3s, 1 min, 10 min, 1 hour) Average wind speed is less when averaging time increases

•

Dominant wind type Averaging times are dependent on storm types (t i l cyclone, (tropical l synoptic ti storms, t th thunderstorms, d t gales) l ) Most regions experience different wind types, however the most extreme one is normative

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Parametric core shelter design Shelter standard: min.18 m/s

1. Regional/national conditions for basic wind speed (averaging time undefined) Existing Wind speed classifications Beaufort

1‐9

West African Buidling Code

1

IFRC / Arup International Holmes

10‐11 12 2 MEDIUM

I

II A

Saffir Simpson

/ Architecture, Building and Planning

3

LOW

Australian Standards / Holmes

0

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Shelter standard in case of Hurricane prone area: 45 m/s (averaging time undefined)

20

HIGH III

IV

V

B

C

1

2

30

D 3 40

hourly wind speed (m/s)

5

4 50

60

70

Parametric core shelter design Wind speed classification based on storm types Very useful when no exact local wind speeds are available or known Prevailing wind types normally are!

Wind zone W1 W2 W3 W4 W5

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10‐min 10 min mean (m/s) 0‐20 20‐31 31‐35 35‐45 45‐55

Storm types

Synoptic storms / Thunderstorms (3s) Weakening tropical cyclones (Moderately) severe tropical cyclones Severe tropical cyclones

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1h mean (m/s) 0 ‐ 19 19 ‐ 29.5 29.5 ‐ 33.5 33.5 ‐ 43 43 ‐ 52.5

3‐second gust (m/s) 30‐45

Parametric core shelter design Calculation of extreme wind pressure on shelter (local conditions) • • • • •

Terrain roughness Building height Turbulence intensity Orographic effects Aerodynamic effects due to shelter dimensions and form

Windspeed → Wind pressure

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Parametric core shelter design 3. Calculation for structural safety • reference f period i d (predicted ( di t d lif lifespan off th the b building) ildi ) • risk of exceedence (yearly extremes statistically independent) • Partial safety factor The partial safety factor in the structural calculation is used to factor up the return period of the extremes Partial P ti l safety f t factor f t (1.6 in Eurocode - 50y reference) Windward Antilles: 2.22 (1.492) - Hurricanes the Netherlands: 1.35 (1.162) - Synoptic storms Underestimation / overestimation of risk: • A shorter return period substantially decreases the loads applied • It is not legitimate to introduce a standard safety factor for worldwide application • Different risk profile for different types of loadings (wind / earthquake / floods) /Shelter Research Group

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Parametric core shelter design Modularity of components

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Parametric core shelter design System approach • Weight optimization based on combination of loading zones • 3 system variants fully calculated using 3d modelling 330 kg (=100%)

Snow zone

snow load 2 (kN/m )

S0

0

S1

0 ‐ 0,5

S2

0,5 ‐ 1,0

S3

1,0 ‐ 1,5

Wind zones

W1

W2

W3

W4

W5

35‐45

45‐55

10‐min mean (m/s) 0‐20

20‐31

31‐35

276 (83%) 203 (62%)

231 (70%)

S1-W2a e.g.: non mountainous areas in southern Europe S3-W2a e.g.: mountainous areas in Pakistan S0-W4 S0 W4 e.g.: coastal regions in hurricane prone areas, e.g Australian coast line, Philippines, Chinese coast line, Leeward islands, Southern Florida, Louisiana /Shelter Research Group

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Haiti 2 storey family shelter Goal: design a 2 storey house structure Available information beforehand • global dimensions • Location (country) • Self help solution

Design and calculations − Several variants and existing g solutions were studied − Focus on connection details and foundation solution /Shelter Research Group

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Haiti 2 storey family shelter

Detail 1

Detail 2

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Detail 3

Haiti 2 storey family shelter Proposed suggestions from Haiti at the time of the final calculations in NL • Addition of door openings during calculations (in stability planes) • Alteration of global dimensions based on standard wooden sheet dimensions − Less effort on crafting of sheeting does not necessarily mean lower costs, because it can have structural implications!

Conclusions from this project • Clear brief saves time, effort and costs • Some existing structures might not be fully reliable (stability / resistance to uplift forces) • Unclear which standards to use for calculation • Foundation: − No soil information available or delivered − 1 m3 concrete per corner post, a total of 4 m3 − Solution: Sol tion hea heavy anchoring (speciali (specialized ed compan company))

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Collective Centre 1. Transport (30ft container) 2. Assembly of base module 3. Beacon for arriving refugees 4. First aid facilities 5. Extension 6. Centralized community shelter g facilities 7. Long-term 8. Disassembly / re-usable

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Collective Centre Demands and result: • Quickly available and deployable • Reliable & proven technical solutions • Uncomplicated assembly • No necessity for trained crew, only locals • Flexibility y • Climate control

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Collective Centre Assembly and deployment

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Collective Centre

Aluminium guidance rail

fabric welded string

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Collective Centre Assembly of membrane

pull

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Collective Centre Transport 30 ft container

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Full Scale Testing of 1 segment

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Full Scale Testing of 1 segment

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Further goals for the sector What is still needed in shelter engineering?

• Globally applicable building standards for sheltering and temporary structures • Insight and agreement on acceptability of risk in relation to financial feasibility • Mapping of hazards and loading extremes

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Thanks for your attention

TU/e Shelter Research Group http://www.innovativeshelter.com