THE FIJI INSTITUTION OF ENGINEERS Winston - FIE... · basis driven by The Fiji Institution of...

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CYCLONE WINSTON DAMAGE ASSESSMENT

FINDINGS & MOVING FORWARD

by

THE FIJI INSTITUTION OF ENGINEERS

for

THE GOVERNMENT OF FIJI

The Fiji Institution of Engineers

CYCLONE WINSTON

DAMAGE ASSESSMENT

FINDINGS

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1.0 INTRODUCTION

This presentation summarises the common findings of the 10 consulting firms that ventured out over the last few weeks across the country to assess and report on 219 schools and 27 health care facilities in areas affected by Tropical Cyclone Winston (TCW). The assessments were performed on a pro-bono basis driven by The Fiji Institution of Engineers in assistance to The Government of Fiji as part of the re-building process.


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Assessments of schools and health care facilities were undertaken in the following areas; • Tailevu • Rakiraki • Tavua • Vatukoula • Ba • Lautoka • Nadi • Sigatoka

• Yasawas • Mamanucas • Ovalau • Taveuni • Bua-Macuata • Cakaudrove • Vanuabalavu • Lomaiviti Group


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The findings are presented through the following; • Common Modes of Failure – typical failure types

and damages due to TCW • Factors Contributing to Damages – other factors

elevating the extent of damage apart from the direct impact of a Category 5 cyclone

• Considerations & Moving Forward

• Short to Intermediate Solutions • Long Term Solutions • Immediate Resolutions • Medium to Long Term Resolutions


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2.0 COMMON MODES OF FAILURE

Damages observed in the affected facilities include the following common modes of failure; • Gutters, downpipes, fascia & flashings; • Windows & doors; • Roof cladding; • Roof framing – various forms of failure; • Ceilings – including electrical and other services; • Walls; • Completely or badly damaged structures; • Damages to site services - water tanks, fencing,

power distribution lines, etc.


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2.1 Gutters, Downpipes, Fascia & Flashings

• Most common type of damage – dislocation, distortion and blow out of guttering, downpipes, flashings, etc

• Damage widely accepted and common even in Category 2 type cyclones

• Damages quite easily repairable as part of short to intermediate re-build


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2.2 Windows & Doors

• Broken windows and damaged doors - common mode of failure observed and typical in most cyclones

• Generally most damage occurred due to flying debris and construction materials – most facilities not having any form of shuttering

• Easily repairable in buildings that have undergone slight to moderate level of overall damage


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2.3 Roof Cladding

• Very common damage in TCW – most damages associated with partial and complete blow out

• Damages in local areas very common – poor detailing of local areas - widely spaced purlin support

• Type of damage generally common in poorly constructed facilities even in Category 3 type windspeeds


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2.3 Roof Cladding (cont.)

• Fixing of roof cladding typically nailed in most facilities inspected – cyclone screws widely used now

• Inferior cladding & products observed – thin gauge cladding typical with inferior fasteners (raptured)

• Easily repairable if support structure not damaged as part of short to intermediate re-fix


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2.4 Roof Framing

• Complete, partial and localised failure in various roof framing elements common

• Failure mainly due to poor holding down of timber trusses and rafters - substandard construction using No. 8 wire and in most cases (for old buildings) using skew nail fixing over wallplates


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2.4 Roof Framing (cont.)

• Condition of roof framing materials also major factor in failure – timber splitting, rotting, termite infestation quite common

• Insufficient holding down of purlins – skew nailed and No. 8 wire fixing observed to most facilities

• Poor truss connections and inadequate member sizes


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2.4 Roof Framing (cont.)

• Short/intermediate term re-build possible in roofs that are partially damaged – to start using facility

• Timber roof framing generally more difficult to repair and retrofit

• Replacement where extensively damaged, should be based on long term solutions potentially involving complete demolition and re-build


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2.5 Ceilings

• Common in most cyclones even in Category 2 – water damage to ceiling linings, lights, electrical fittings, etc

• Important to note that immediate use of facilities would require replacement of water damaged ceilings as part of short to intermediate repair – to avoid risk of collapse


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2.6 Walls

• Timber wall structures generally suffered extensive damage – walls were found to have poor connections, poor bracing and in deteriorated condition due to age

• Concrete walls performed reasonably well, however, strength and stability needs to be checked in detail - some cases involved collapse in concrete walls due to poor construction and lack of reinforcing


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2.6 Walls (cont.)

• Timber structures that are damaged significantly recommended to be demolished and built in concrete with new roof

• Concrete wall structures have more potential for retrofitting to resist required uplift and lateral loads should walls be under-reinforced – more dependent upon intrusive testing and investigations


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2.7 Completely or Badly Damaged Structures

• Completely or badly damaged structures typically involved old structures built in timber

• Poor connections, tie downs and deteriorated member conditions and age were common factors

• Re-build recommended in concrete construction with new roof in compliance with NBCF (more long term solution prioritized as a intermediate need)


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2.8 Damages to Site Services

• Water tank damage was a commonly observed to most of the facilities visited – either blown off, dislocated or raptured - lack of tie down major factor

• Other damages included fencing damage due to flying debris and fallen trees

• Broken telecom and power lines within facilities quite common


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3.0 FACTORS CONTRIBUTING TO DAMAGES

The damages were fairly consistent amongst findings of the various Structural Engineers involved with rapid assessments. Most damages occurred as a result of one or more of the following contributing factors further elevated by damaging TCW windspeeds; 3.1 Lack of Periodic Maintenance • Inspection & replacement/repair of structural

elements appears to have been left out - “contributing to failure”

• Most buildings - do not appear to have structural upgrades since built, however more aesthetic, painting, etc – “structural upgrade much needed to NBCF compliance”


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3.0 FACTORS CONTRIBUTING TO DAMAGES (cont.)

3.2 Building Age • “Nothing lasts forever” – most roofing materials in

poor condition - rotten, splitting, poorly connected, old – pre NBCF construction techniques – needs major rehabilitation long term

• Building age ranges from 30 to 70+ years for most facilities and has been rattled by many cyclones

3.3 Poor Construction & Workmanship • Use of substandard & inferior materials, poor

workmanship, lack of knowledge on standard practice

• Not following drawings and specifications • Lack of Supervision by Qualified Engineers


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4.0 CONSIDERATIONS & MOVING FORWARD

4.1 Short Term to Intermediate Solutions • Repair and reinstatement of facilities to pre-

cyclone condition particularly for buildings that suffered minor to repairable form of damages - for full use

• Not necessary the compliant solution, but re-build items should be “equal or better” with some degree of compliance

• For buildings completely destroyed or extensively damaged, intermediate solutions may not be required - new re-build recommended for long term solution in compliance with NBCF, however, prioritised as part of an intermediate need


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4.0 CONSIDERATIONS & MOVING FORWARD (cont.)

4.2 Long Term Solutions • Consideration to re-construct roofs in strict

compliance to NBCF - most common failures were in roofs

• Re-build completely new or where necessary retrofit to NBCF compliance including those buildings that were not damaged

• Potential for retrofitting depending on material condition, type and age requiring further detailed structural investigations

• Timber structures – completely damaged buildings were mainly of timber construction - long term solution should consider concrete form whether or not existing timber buildings suffered damaged


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4.3 Immediate Resolutions • Build Back Sector • Shelters Clusters not part of FIE scope – should

ensure proper design, construction compliance and monitoring/supervision

• Education & Health – require design and re-building to NBCF – monitoring under guidance of an FIE Professional Engineer

• Materials Compliance, Code & Standards • Materials – designers to ensure compliant materials

used with strict monitoring to ensure its correct use during construction


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• Codes & Standards Adoptation – designers to continue the use of the current edition of the National Building Code of Fiji

• Re-build to be designed accordingly and to be classified by importance level depending on number of occupants expected in the building

• Possible consideration in designing one building in facility for specific “Post Disaster Function” – for functioning as a evacuation center


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4.4 Medium to Long Term Resolutions • Registry of Professionals & Builders • Strengthen FIE capacity – more resourcing, funding • Strengthen registration of Engineers, Architects,

Quantity Surveyors, Valuers, Land Suveyors, Builders, Electricians, Plumbers, Specialist Trades, Draftsmen, etc

• Enforcement Agencies • Training – improve skills , awareness of codes and

compliance • Strengthening – more resourcing and skilled

personnel required to enforce stricter compliance


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• Awareness & Publicity • Building Codes – needs to be used by all industry

service providers • Home Builders Manual – forms basis of domestic

low cost housing - should be widely adopted document for all residential construction

• Build back better – awareness in the need to build compliant structures – needs common understanding and agreement between all stakeholders (Government, Private & Non-Government Sectors)


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4.5 Summary Moving Forward • Prioritising re-building – which facilities to be done

first, priority and staging • For structures with slight to moderate level of damage

– potential for a short to intermediate repair for immediate re-use (not necessarily a compliant structure but allows facility to be re-used)

• Long term solutions to follow up intermediate repair to ensure compliance to NBCF is achieved (based on prioritising the need against funding)

• For structures badly damaged or destroyed, intermediate re-build shall be based on long term solutions fully compliant to NBCF


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4.5 Summary Moving Forward • Timber structures (damaged or not) recommended

highly to be demolished and re-built in concrete construction – long term goal for timber structures

• Re-building of facilities should consider provision of back up water and power supply – tanks potentially sized for post disaster relieve with sufficient water and power for few days of immediate relieve after a cyclonic event

• Specific designated evacuation centers to be identified by the Government – potentially one building built strong with back up water/power to higher Importance Level – costly but much needed


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4.5 Summary Moving Forward • Re-building to be done with strict compliance to NBCF

– designed, documented and supervised construction to avoid repeat of poor workmanship, substandard construction techniques and inferior build quality

• Strict use of materials – in compliance to acceptable codes and standards outlined in NBCF

• Channelled through FIE, the need for respective committees to monitor design standards and materials; • Building Code and Standards Committee; • Building Materials Committee

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