BahayTUKO Slotted Confined Masonry System Domestic Construction in The Philippines Perhaps a time for change?
SAMANIEGOMORGAN Landline: Smart Mobile: Globe Mobile: Email: Website:
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ARCHITECTS & ENGINEERS Estudyo Bahay Tuko B9L13 Narcissus Street Barangay San Luis ANTIPOLO Rizal Province Republic of The Philippines
BahayTUKO Slotted Confined Masonry System © SAMANIEGOMORGAN Antipolo June 2015
SAMANIEGOMORGAN The Partnership was formed in May 2010 between British Architect Bob Morgan, and Local (Philippines) Partner Ollie Samaniego. Bob is the Operations and Design Partner for the Practice. Ollie is the Business Partner, and Representative for Local Projects. We operate as a Traditional Equity Partnership, under Philippines Law. The Practice is registered with the Securities & Exchange Commission (SEC), and Bureau of Internal Revenue (BIR), in Manila. All Architects and Engineers are registered with the Professional Registration Council of The Philippines, and are members of the Manila Society of Engineers.
Figure 1 The 'Original Bahay Tuko' in Antipolo. The renovation of a Dilapidated Villa carried out in 2011 This is now 'Home, Office and Studio' combined. Trades and Labour came from 'Tried and Tested' sources, and Build Quality was exceptionally good. However, Supervision was almost constant for the 3 Month Build.
Our Scope of Operations has extended far beyond the Field of Architecture over recent years. So much so, that the Practice has a Diversified Programme of Extra-Curricular Development. This is part of the Practice Policy of 'Continued Professional Development.' As such, each Member of Staff is encouraged to pursue a 'Topic of Professional Relevance' that contributes ultimately to both the Enhancement, and Promotion of the SAMANIEGOMORGAN Brand and the Services that we offer. The BahayTUKO Slotted Confined Masonry System was part of my contribution to those efforts as Practice Principal! – I became Frustrated with Failed Construction, Inept Contractors, Demanding Clients, Poor Quality and a Perverse Level of Building Code! Consequently, we went 'Back to Basics!' Enjoy the Document, as it will undoubtedly reveal some very Salient and Profound Facts relating to Philippines Construction Practices! – Very different to the European and UK Norms!
R J Morgan BA(Hons)Arch Dip Arch ARCHITECT 30156-D01-15061701
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Introduction This Document, attempts to give some Historical Background regarding the use of Reinforced Concrete Frame and Hollow Block Infill, within The Philippines, for Domestic Structures. It also Highlights many of the Practical Disadvantages of this Form of Construction. (As will be evidenced.) Alternative Structural Systems are also addressed, as are some of the fundamental theories of Seismic Design related to Structure still remain to be adopted in the context of The Philippines! – Here an 'Outside View and Guiding Light' are necessary! Finally, an Introduction is made to a Practical Alternative – The BahayTUKO Slotted Confined Masonry System. Some might consider this to be somewhat Radical – However, it adopts accepted International Norms, in terms of Structural and Seismic Design; It also uses Existing Reinforced Concrete Technology and deviates little in terms of Materials. In short, it has the same Basic Ingredients – But puts them together in a more Efficient and Builder-Friendly way!
Figure 2 'Bahay Tuko' – Not too far removed from the Concept Design (Figure 1) The Property was built in 1980, and is a typical 'Economic Home' of the Marcos Era. The Roof was finished with a Thin Gauge Corrugated (Un-Galvanised) Steel Sheet, which had largely rusted through. Rafters were of Timber, and had been 'Eaten by Termites!' However, the Original Wall Structure and Foundations were Structurally Sound! The Location is Elevated and Sheltered. Neither is it susceptible to Flooding or Typhoons. This area of Rizal Province carries the Lowest Seismic Risk Rating, yet Antipolo Municipality still insisted on Reinforced Concrete Frames and Block Infill – Despite there being no Seismic Events within Living Memory!
Quite simply, the Study has 'Dissected' Existing Methodologies; it has 'Analysed' them in terms of Design, Relevance and Practicality. Then, it has 'Reconstructed' them in order to create a very simple 'Overhauled Structural Blockwork System!' It should be remembered that Philippines Construction is generally quite poor in terms of Quality – This relates to Quality of Construction Design & Specification, Quality of Materials, and Quality of Workmanship. To some extent, we can see a 'Developing Country' that is caught in a 'Technological Time-Warp,' regarding Construction. If an analogy could be drawn, it should relate to Car Manufacture and the Motor Industry. Philippinos tend generally to be more demanding as 'Consumers' when buying a Car, than they do when buying a New House – This despite a 'Quantum Leap' in terms of a commitment to Borrowing and Investment. Mortgage Interest Rates have an APR or approximately 10% with Chattel Loans for Cars at 20% APR! (Source: Banco de Oro 16 June 2015)
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On the one hand, their New Car must have the latest 'Bells and Whistles;' yet their New House, will have neither Hot Water (Compulsory in the UK since 1936 and the Public Heath Act), nor an adequate Kitchen. It will also be delivered late by the Developer, and in an incomplete state. "But do not worry – The Neighbours cannot see the 'Pail Flush Toilet!' – However, they can see my Brand New Toyota Corolla on the Drive!" Fortunately, this situation is changing – Albeit slowly! Returning Overseas Filippino Workers (OFWs) have experienced both living and working in more developed countries. They have experienced first-hand, enhanced levels of Quality and Specification. Consequently, they aspire to the same standards once back on their 'Home Ground.'
Figure 3 A Typical 3 Bedroom Home from the Private Economic Housing Sector (A Design Proposal for Camella Homes). This particular developer had severe problems in terms of Reputation and Quality – Materials, Workmanship, Construction, and the 'Purchaser Experience!' Their problems were mainly due to a 'Love Affair with Thrift' that verged upon 'Incestuous!' Easter 2015 was one of the Main Events in the Company's Calendar. Traditionally, and largely due to the end of the School Year, sales of New Homes 'Peak' during April and May. However, this year Net Sales on one Camella Site were measured in Negative Numbers! Negative Numbers? – Initial Reservations had been made 'Off-Plan' over the Internet. However when OFWs returned for the Easter Break, and saw the 'Real Deal' they cancelled immediately! Part of our Commission was not only to 'Improve and Unify' the House Type Range, but also to improve 'Buildability!' Many of the House Type Models had long served their purpose, and were in need of 'Radical Invasive Surgery,' rather than a mere 'Cosmetic Facelift!'
Key to issues of 'Quality' is the Construction Process itself. Resistant to change, it is also intolerant of innovation. Quite often, a New Idea of Merit will come along, only to be 'Kicked Back' because if fails to fulfil the most trivial of Administrative Requirements. In such instances Legislation goes into Reverse Gear! – Rather than 'Encourage Innovation,' it maintains a rather Stagnant and Stale Status Quo! – Reinforced Concrete Frame, with Blockwork Infill! BahayTUKO In Tagalog 'Bahay' translates as 'House' and 'Tuko' is a Gecko. 'Bahay Tuko' is the name of the house that was renovated in 2011. This, and subsequent projects in The Philippines using Hollow Blocks and Reinforced Concrete Frames, provided the motivation for the study. There are many 'Bridges to Cross' for the BahayTUKO System. Presently it exists merely as a Concept Design, 3D Computer Models and some Physical Models. It requires improvement and Development, in terms of Prototyping, Testing, Process Engineering and Manufacture. The Philippines is seen as the ideal environment for the Development Process to happen – Albeit that it might take a little time!
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BahayTUKO Slotted Confined Masonry System
PART 1 Background Information Historical, Political, Social, and Economic
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Reinforced Concrete Frame with Hollow Block Infill – Cheap and Cheerful, Low-Tech! - Yet a Construction Nightmare, and a Disaster Waiting to Happen! Yes, 'Hollow Blocks' are Cheap! They also use Low Technology, with the majority being manufactured by Builders’ Merchants in their otherwise Vacant Back Yards, as a 'Cottage Industry!' However, there are no Quality Standards! - Labour is invariably Casual and Unskilled, with both the 'Ingredients and Recipe' for Concrete being 'Variable.' In essence 'You Pay for what you get!' – Or in the case of The Philippines, 'You still Pay for what you DO NOT get! – In Advance!' – All will become clear, as we proceed . . .
Figure 4 A Delivery of Hollow Blocks for the Bahay Tuko Villa Refurbishment, that were manufactured locally. Finished Quality was reasonably good. However, note the 'Damage in Transit!' – A mere 4 Kms! The Blocks had to be covered with Hessian Sacks, regularly sprayed with water and left for two weeks before being used! When delivered, the Concrete was still 'Green!' Domestically produced Blocks are invariably manufactured using an almost 'Dry Mix Matrix.' Once poured into a Steel Mould, the Blocks are 'Momentarily Vibrated' on the Table of the Casting Rig. They are then Ejected from the Mould, and Laid-Out to Set and Cure. Many will NOT be covered and are left exposed to the Sun. Neither will they be periodically 'Doused' with water. Sample Blocks from each Delivery were tested using an 'Improvised Rig!' – A Hydraulic Car Jack, and a Pressure Gauge. Surprisingly, the Blocks consistently reached 3 N/mm2 (Once Cured at 28 Days).
The main topic of conversation between Contractors, Developers and the Self-Build Community is usually ‘How Cheaply’ they managed to obtain their last load of Hollow Blocks! When Ex-Works Prices reach 'Commercially Suicidal Levels,' then something ‘Has to Give!’ The simple answer here is that in order to obtain a ‘Cheap Price’ the Most Expensive Ingredient has been Cut-Back! - Cement! Either that, or the Cheaper Ingredients got even cheaper! - No Washed Sand, and/or Rejected/Returned Blocks, 'Crushed' in order to extend the Aggregate Content! – Not forgetting 'Ordinary TapWater,' which contains a large content of Chlorine and Fluorine! – Sulphate Attack before you even 'Mix the Ingredients!' Commonly, the average load of Hollow Blocks is delivered by a 3 Ton Truck, 'Off-Duty' Jeepney, or a Motorcycle and Sidecar! The Blocks will have been handled manually upon both Despatch and Delivery - There are no Fork-Lift Palettes, or Crane OffLoading, as most Contractors (Large and Small) do not have Fork-Lift Trucks on site! In order to keep Overheads low, they carry very little or NO Plant at all! - However they do, have an abundance of Cheap (Ham-Fisted) Labour instead! In many Rural Provinces the Carabao (Water Buffalo) is common on Construction Sites, and used as a 'Beast of Burden.'
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Well, they consider it to be 'Cheap Labour!' – At least in their own minds! It loses its attraction however, when Site Overheads accrue when the Contract Term overruns; as it invariably does! – Thus generating another Loop in the 'Downward Spiral!' As we shall see here, the Cheapest Short-Term Expedients usually have the habit of becoming the Most Expensive Long-Term Solutions! There is much to be learned from the maxim of, 'Do it Right! – The First Time!' However, the Local Culture is one of spending inordinate amounts of time attempting the 'Cheat the System!' Consequently, Blocks have at least Two Opportunities to become damaged and unusable. A Third Opportunity is 'The Journey' itself! Deliveries may well contain as much as 30% Damaged Blocks! For the Small Builder, budgeting from his own wallet, there is little or no redress with the Merchant! – 'Cash Before Delivery' is the usual Basis of Payment! It then becomes a case of ‘Pwede Na' (Making Do), or spending further cash on replacements. As the level of Local Quality is 'Consistently Poor' there is very little point in 'Shopping Around!' – Just use Cement, and 'Glue' the broken ones back together!
Figure 5 'Improvisasyon!' A selection of Improvised Tools made from Rebar! Note the 'Safety Flip-Flops!' After this photograph was taken, and I discovered their 'Hoard of Defective Second-Hand Tools,' the Tradesmen and other Site Workers were taken to the Local Hardware Store – They thought that Christmas had arrived early! Tape Measures, Spirit Levels, Builder's Level, Tile Cutters, Saws, Chisels, Mallets, Set Squares, Mitre Blocks, a Selection of Hammers and Screwdrivers, Trestles, Multimeter for the Electrician (Rather than a Light Bulb on the end of a Wire!), Tap & Die Set for the Plumber, Spanners, Monkey Wrench, Mole Grips and Drill Bits were all bought. Together with Hard Hats, Boots, and Gloves! – No more 'Safety Flip-Flops' and 'Hard Head Scarves!' Quality Work cannot be produced with Defective and Broken Tools! – And, there is no point in complaining about Quality and Speed, unless Tradesmen have what they need! – Their 'Daily Rate' PHP 500/- Per Day (US$ 11) does NOT cover the Purchase of Tools!
Those familiar with practices in the UK and Europe will be used to Factory Manufactured Blocks, Steam Curing, Paletisation, and Quality Assurance. The norm in the UK is to use 3.5N/mm2 Perforated (Not Hollow) Blocks for General Construction. Denser Solid 7.0N/mm2 and 15N/mm2 are used Below Ground, and also for FairFaced and Structural Masonry – With a Plethora of Insulated Blocks! Blocks in The Philippines however, (Due to a Low Cement Content), will rarely achieve 1N/mm2. The use of Very Course Aggregates also precludes their use for Fair-Faced Masonry. Blocks are 400mm Long, 200mm High, and either 100mm or 150mm Thick. There are no Reveal Blocks, or High Strength Padstone Blocks available either. Some Merchants produce 200mm Blocks (To Order), However, the 'Get-Around' is to construct two skins of 100mm, 'Cross-Tied' together! – 'Improvisasyon Lang!' 'Bobz Test' for a Hollow Block, is to take it from the Merchant's Yard and 'Drop it on the Ground!' (From Waist Height) If it breaks, the Supplier has 'No Chance' in providing me with Blocks! – If it remains Intact? – They might have 'Half a Chance!' 30156-D01-15061701
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Loadbearing or Non-Loadbearing? That is the Question! - But does anyone know what it really means? The National Building Code of The Philippines (PD 1096:1977), indirectly precludes Loadbearing Masonry for Domestic Construction. Instead it follows a ‘Monoculture’ of In-Situ Reinforced Concrete Frames, with Non-Loadbearing Infill Panels. The Motivation for this, was (Supposedly) based upon Seismic Design. However, the Low Ductility of a Reinforced Concrete Frame (Unless ‘Designed Correctly’) becomes at the very least, 'Questionable.' This is particularly relevant to Philippines Construction where what 'Practical Design' that does exist, is usually 'Empirically Based,' and will therefore, incorporate a substantial element of 'Overdesign!'
Figure 6 The aftermath of Hurricane Sandy in the 'Former United States!' – And, an example of 'Protectionism via Building Code!' However, the 'Gravy Train' just came to an end for the 'Timber Frame Lobby' in South Carolina! Many Building Insurance Claims still remain outstanding. The 'Final Account' for Hurricane Sandy is estimated at some US$ 60 Billion! Engineers, Loss Adjusters and Insurers have questioned the use of Timber Framed Construction. However, rather than State Governments and FEMA putting up their hands and saying "Sorry! – We got it Wrong!" The opportunity has been taken to reduce Claims by as much as 30%! Quite 'Mysteriously' many properties have been declared as having 'Pre-Existing Structural Issues' prior to the Hurricane Damage! Engineers' Reports have also been 'Adjusted' in many instances, without their consent! A 'Man on the Moon' and 'Number One' still prefers to 'Nail Pieces of Wood Together,' for Housing!
Conversely, it could be construed that the National Building Code (An Enabling Act), intentionally promotes a form of 'Domestic Protectionism.' Construction Protectionism by Building Code, can be ably demonstrated with events in America - One 'Model' Federal Building Code, is ‘Adapted’ for each State - With even certain Cities, and Enterprise Zones having their own Building Codes too. (Perhaps America should now be referred to as 'The Former United States?') Consequently, there is ample opportunity for the State Supplementary Code to be ‘Engineered’ (Via Political Lobbying), around predilections for Indigenous Local forms of Construction – Irrespective of their relevance or appropriateness! – Pure and Simple, the argument revolves around 'Money!' – And who can shout loudest! Following Hurricanes Sandy and Katrina in the US, the Structural Integrity of Timber Framed Housing under such conditions became 'Questionable' in certain States. Their Local Supplementary Codes had conspired with the Woodworking Industry to preclude Masonry Construction! – Or any other form of Non-Timber Construction! Moreover, and as an 'Ironic Twist,' Post-Disaster Prefabricated Solutions were promoted as part of the FEMA Sandy Relief Programme. However, the Local Supplementary Codes outlawed Prefabricated Construction! - Factory Built Assemblies had to be ‘Dismantled’ for Inspection, and then Reassembled! 30156-D01-15061701
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This somewhat defeated the very nature of Prefabricated Construction, and Timely Remedies! A 'Man on the Moon' and 'Number One' still prefers to 'Nail Pieces of Wood Together,' for Housing! Across on the other side of the Pacific Ocean, the Politics of Philippines National Housing Provision (Public and Private) is far too Complex, Benighted and Perverse to deal with here. Suffice to say that the National Housing Authority (NHA) and Housing Land Use Regulatory Board (HLURB) are promoting Concrete Framed Buildings (Private Sector Funded), ‘For Sale’ as part of the Post-Yolanda Relief Programme! – 'Mmmmm, Privately Funded Relief Housing for 'Cash' from a 'Destitute Population' that has lost everything it had! – I am sure that will be a 'Rip-Roaring Success! Consequently, Post-Disaster Housing Provision can accordingly be described as ‘Lamentable!’ Private Developers and Contractors are discouraged by Low Margins, and Capitalising for Projects on behalf of The Government! – Not to mention exceptionally long Construction Programmes, before they yield any Return on Investment.'
Figure 7 While parts of the 'First World' prefers to 'Nail Pieces of Wood Together for Housing,' In the 'Third World,' there is often insufficient Cash to even buy Nails! – It is needed for Food! However, Bamboo, Coconut Lumber and Vines are available for free! – Very often from the Side of the Road! Following Typhoon Yolanda in 2013, Government Housing Relief was slow to arrive! A Displaced Population was still living in Communal Emergency Accommodation (Covered Basketball Courts and Barangay Halls) One Year after the devastation occurred. The 'People' took matters into their own hands, and built their own! The Single Space 'Kubos' are made from Bamboo. The roof is finished with 'Nippa' (Dried Banana Palm Leaves). The Bamboo Frame is skilfully 'Jointed and Bound.' Tired of Waiting, Local Communities formed their own 'Informal Cooperatives.' Fabrication was a Group Effort. The Structures are resistant to Seismic Events, and provided they are 'Tied-Down' to Ground Anchors, they can withstand Typhoon Damage – Especially when grouped together.
The reality in 2015 (Dealing with a Disaster of 2013) is that New Homes 'Built Back Better' have 'Failed to Happen!' – But 'Hey, Who Cares?' – 'These are Low Income Provincial People, far away from the National Capital Region!' – Laissez-Faire! Immediate Politics apart, we have a National Building Code that has embraced Concrete Construction, using the ‘Guise’ of Seismic Design! – However, do those 'Lauded Seismic Principles' really have any foundation?
What about Seismic Design? Seismic Design is the apparent 'Raison D’Etre' of the National Building Code, and Domestic Construction Practice. However Internationally, The Earthquake Engineering Research Institute (EERI), in its Publication WHE-2006-03 of 2006 did not receive a Single Contribution from The Philippines! This, notwithstanding, over 200 Technical Papers submitted from other contributing Engineers from around the World!
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The resultant document was published, 'AT RISK: The Seismic Performance of Reinforced Concrete Frame Buildings with Masonry Infill Walls.' This can at least be considered as a 'Seminal Work;' as it 'Questioned' many long-standing Principles of Seismic Design and Construction Practice. Surely the title alone should have been sufficient for Philippines Engineers to at least 'Take a Second Look?' – Or 'Perhaps Not,' as it failed to 'Tick the Box' marked 'What's in it for me?' On the part of Municipality Engineers! – In short, the EERI Document began to threaten the 'Status Quo' and heralded a possible end to an 'Era of Engineering Featherbedding,' for Local and Regional Government. Primarily, the Report 'Questioned' Reinforced Concrete Frame with Hollow Block Infill! Secondly, it 'Coalesced' Design Principles from various affected Earthquake Zones from around the World; and promoted alternatives to the Reinforced Concrete Frame with Blockwork Infill. However, at the time, two other Structural Systems had arrived on The Philippines Market, that are worthy of consideration. Viz.,
Lightweight Pressed Metal Frame
Figure 8 Bahay Quines (Caloocan, Manila). A Four Storey House in part of Old Manila, using the SpeedSTEEL Pressed Metal Frame System. This house was a replacement for an old Timber Framed Property. This area of the City is only marginally above Sea Level, and is prone to flooding – Especially after 'Improvements' were made to the Storm Drainage System! – Merely raising Road Levels! The Ground Floor was therefore, Elevated 1.5m above Road Level, using a Massive Volumetric Concrete Foundation, which also contained the Septic Tank. The Steel Sections were Pre-Cut and Drilled in the Fabrication Workshop. They were then Labelled and Packaged as Logical Elements. A Team of Four then assembled the Frame. A Second Team followed pouring the Concrete Floors onto Corrugated Decks. Finally, a Third Team filled the Void Spaces in the Walls.
This can be regarded as a 'Generic' rather than a 'Proprietary' System. It has been used around the World for a number of years, and has found favour in Seismic Risk Zones. Latterly, it has made inroads into the Middle-Eastern Markets, which had previously relied entirely upon Reinforced Concrete Frame and Blockwork Infill. The System uses Standard (Dry Wall) Lightweight Pressed Metal Sections, which are assembled into a Complete Frame. The Interstices and Voids are then filled with a Matrix of Crushed Blockwork and Sand Cement Mortar. Internal and External Faces are then Rendered/Plastered with Sand Cement Mortar. Insulation is optional. If we regard Reinforced Concrete Frame and Blockwork Infill as a 'Chassis' Type of Design; the Lightweight Pressed Metal Frame is very much the 'Monocoque' Version.
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Its inherent strength comes from Structural Continuity, with the Entire Structure behaving 'As One.' In terms of Seismic Design, this achieves a High Level of Ductility, as Loads (Live, Dead, Wind and Seismic) are carried proportionately by all Panels and Elements within the Frame. It has distinct Seismic Design Advantages over Reinforced Concrete Frame and Blockwork Infill, and also achieves a generally more 'Slender' width of wall. When tied, to a 'Massive Foundation,' it offers an almost 'Perfect Seismic Solution.' The System is however, quite Ponderous and Slow; having little advantage in terms of Construction Time over Reinforced Concrete Frame and Blockwork Infill. Semi-Skilled Labour is also required for the Frame Assembly, with Continuous Supervision for the Infill. The System has found favour with several Municipalities within The Philippines, and is an adopted Mode of Construction preferred by the NHA & HLURB as part of the Post-Yolanda Recovery Programme in Leyte and Samar.
Precast Concrete Column and Panel Those familiar with the Post WW2 Prefabricated Housing Programme in the UK will recognise this system immediately; as being derived from The Cornish Unit. It is based upon Precast Concrete Fencing Technology. One Philippines Fabricator however, alleges 'Patents and Design Registration!' Non Nova Sed Nove! (New But Not New!) Or in the Colloquial 'Same Same but Different!' However, Design and Patent Registrations cannot be found. Therefore, it should be regarded as another 'Generic' rather than 'Proprietary' System. Figure 9 Precast Concrete Columns and Panels. This is essentially 'Fencing Technology.' The System is based upon the Post WW2 Prefabricated Cornish Unit from the UK – Contrary to popular belief, it is NOT a Patented Philippines System! – As some would have you believe!
Unfortunately, the Precast Concrete Column and Panel System results in a somewhat 'Utilitarian Interior' – An Internal Finishing Skin is an 'Optional Extra!' It also suffers the same Design Traits as the 'Post WW2 Grandfather System!' – Water Penetration around Panel Joints, and Corrosion of the Column Reinforcement. 30156-D01-15061701
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The Environment of Manila has a High Salinity, compounded by Acidic Pollution. Panels are a mere 50mm thick, and there is only Nominal Concrete Cover to the Reinforcement in the Columns. Neither have Concrete Mixes been modified, to take account of Climate and Environment. The System is a True Reinforced Concrete Frame with Infill – The Columns are Independent to the Walls, being supported from Precast Concrete Foundation Modules. Initial Construction is quite rapid - However, In-Situ Concrete Ring Beams have to be cast at the First Floor and Roof Plate Levels. The Ring Beams are substantially larger that the Panels and Columns, leading to rather unsightly 'Banded Elevations!' The System has however, found favour with several Municipalities, for 'Socialised Housing,' and is an adopted Mode of Construction preferred by the NHA & HLURB as part of the Post-Yolanda Recovery Programme.
The Status Quo Figure 10 A Renovated Cornish Unit in the UK. 'Rolled-Out' in 1946 these houses had an intended Design Life of between 10 and 15 Years. Some Seventy Years later, the Cornish Unit, BISF House, and AIROH Prefab still exist as Viable Homes. The Cornish Unit used the Precast Posts and Panels for the Ground Floor only. The First Floor, Walls and Roof used Mansard Trussed Rafters, in order to overcome the necessity for Ring Beams. Essentially, this was a 'Two System House.' Renovation has occurred primarily to the Ground Floor Structure. In many instances Defective Columns and Panels have been 'Extracted.' New Elements have been manufactured using more Durable Mixes of Concrete, protected further with Epoxy Paint Treatment.
Reinforced Concrete Frame and Blockwork Infill still remains the most common form of Domestic Construction. It is also the 'Preferred Solution' of many Volume Housing Developers, and also a large contingent of 'Self-Builders.' Yet, unless 'Designed Correctly,' this System has an 'Achilles Heel,' in terms of Ductility. Very simply, Ductility is the ability of a relatively rigid structure to 'Flex and Yield' under Seismic Stress. Overly Rigid Construction often results in 'Poor Seismic Performance' Whilst Rigid Construction prevents Disproportionate Collapse, it can result in the Collapse of the Entire Structure (In One Piece), as it becomes 'Too Brittle' to absorb the substantial Lateral Loads imposed by Seismic Events. But do not worry! – "If it Falls-Down we will Change the Building Code! – Not necessarily to make Improvements, but purely to exonerate ourselves!" Some might 'Question' the foregoing somewhat 'Flippant Comment.' However, it reflects part of the 'Darker Local Government Culture,' endemic in The Philippines! 30156-D01-15061701
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Other Controlling Factors in the Concrete Debate! The almost exclusive use of concrete in The Philippines is not only dictated by Seismic Precautions. Generally, most of South-East Asia has to deal with Termite Attack. Some Indigenous Hardwoods (Narra, Yakal and Zamora) belonging to the Mahogany Species are almost immune from attack. These species are exceptionally hard to work (Requiring Metalworking Tools!) They are also expensive, and many are covered by a Government Eco-Forestry Ban. In addition to Termites, infestations of Cockroaches are also prevalent; with the Cockroach becoming almost immune to Chemical Treatments. Therefore, most Philippine Homes (Especially in Rural Areas), will encourage the 'Tuko' or 'House Gecko.' They are solitary, nocturnal and avoid human contact. They are exceptionally good however, in dealing with the Common Cockroach, and other Crawling Insects! Figure 11 This Kitchen Design is precisely what was installed in to the Bahay Tuko Villa. Note that the Base Units are raised above the floor on Stainless Steel Legs! This prevents the ingress of Cockroaches and other Crawling Insects. The Concept follows that of NHS Hospital Cabinetry in the UK where thorough Deep Cleaning can take place on a regular Basis. The Carcass Material is Epoxy Finished High Resin Marine Plywood, which is Termite Resistant. Within the Philippines Market it is available as a Furniture Grade. Worktops are fabricated from Oiled Narra (A Light Coloured Mahogany) Alternatively, Solid Laminates can be used – Both being Resistant to Termite Attack.
Timber and Steel Structures also tend to create Void Spaces behind Finishing Materials, Fire Protection and under Floorboards. These spaces provide the Perfect Habitats and Transfer Zones for Cockroaches, Ants, Termites, Mice and Rats. Mice tend to be 'Ground Based,' entering property though open doors and windows. Rat infestations are almost exclusively from 'Brown Roof Rats.' They travel between adjoining and overhanging trees, before dropping into Rainwater Gutters, and entering the Roof Space. During the 'Wet Season' (June to November) larger Black Rats may be displaced from the 'Street Kanals' during periods of Surcharge. As can be seen, Void Spaces of any description should be avoided! Further precautions are required in Roof Spaces and Ceiling Voids, by using Galvanised Steel Conduits. Rats have an appetite for PVC, and Cable Insulation! They have also developed a level of immunity to Wafarin and other Proprietary Poisonous Treatments. It should be obvious therefore, that Massive Contiguous Construction is almost a Construction Prerequisite, for a variety of reasons – Not just Seismic!
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Alternative Seismic Design The Earthquake Engineering Research Institute in its 2006 Paper, proposed Alternative Design Philosophies for Domestic Structures. Viz.,
Reinforced Concrete Frame with Shear Walls and Blockwork Infill In essence this can be regarded as a High Rise Solution (Structures Above 4 Storeys) However, it does have its place particularly when considering SplitLevel Houses in Seismic Risk Areas. Here, there are 'Long Term' Lateral Loads, imposed from Retained Ground that need to be accommodated, together with the Lateral 'Shaking' during a Seismic Event. Shear Walls also assist in instances where both Short and Long Columns exist on the same level.
Confined Masonry To the untrained eye, it looks rather like Reinforced Concrete Frame and Blockwork Infill. Yes, it shares some similarities; however, the approach is somewhat different. Viz., Figure 12 A very simple Shear Wall Model. Note that the Corner Columns, Walls, and Horizontal Slabs are Contiguous Construction. The Shear Walls resist Lateral Seismic Forces, and also reduce Torsional (Twisting) Stress. The solution is ideally suited to either Symmetrical or Regularly Shaped Buildings to be effective. Note that the Blockwork Infill is still Independent of the Main Building Structure.
Masonry Walls Transmit the Gravity Loads from the Slab down to the Foundation, and also resist seismic forces. The Walls must be Confined by Concrete Tie-Beams and Tie-Columns to ensure satisfactory Seismic Performance. Confining Elements Tie-Columns and Tie-Beams provide restraint to the Masonry Walls and protect them from complete disintegration, even in Major Earthquakes. These elements do not Resist Gravity Loads.
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Floor and Roof Slabs Transmit both Gravity and Lateral Loads to the Walls. In an Earthquake, Slabs behave like Horizontal Beams and are called 'Diaphragms.' Plinth Band Transmits the Load from the Walls down to the Foundation. It also protects the Ground Floor Walls from Excessive Settlement in Soft Soil Conditions. Foundation Transmits the Load from the Structure to the Ground. Given the Geography of The Philippines (7,107 Islands), and a Substantial History of Seismic Events, it is not surprising that many other forms of construction exist; reflecting quite a diverse Architecture. If we put aside Seismic Design for the moment, Typhoons are the most common form of Natural Disaster. Therefore, the 'One Building Code Fits All' Solution has become untenable.
Fire! The most common form of ‘Unnatural Disaster’ in The Philippines is Fire! Again, this is another area which is too detailed to investigate here. However, it should be seen that the Building Code seeks to establish Safe and Structurally Sound Construction (Ref: PD 1096 Section 102). Figure 13 The Confined Masonry Structural Model is shown to the Top Left. The Structure is Loadbearing. Whilst the Elements of Structure are relatively Independent, they all Work Together through Structural Continuity. By acting 'As One' the Structure is resistant to Lateral Loads induced by Seismic Stress. It I also 'Ductile' under Torsion. Bottom Right is the Traditional Reinforced Concrete Frame with Blockwork Infill Model.
At the time of writing (June 2015), Fire has once again 'Hit the Headlines.' In May 2015, a Factory Fire in Valenzuela City, Manila (Kentex) claimed 70 Lives, due to Inadequate, Locked and Blocked Fire Exits. The 'Ozone Saga' dating back to a Discotheque Fire in 1996 also re-emerged. With the latter, over 100 Lives were lost, for exactly the same reason! The Ozone Inquiry still 'Plods Along!' – The only compensation made to date has been in the form of Lawyers' Fees! – No doubt, this will continue for yet another 19 Years!
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With 'Fire' becoming the 'Cause Célébre,' Media attention has suddenly shifted to the Infamous West Valley Fault in Metro-Manila (In a 'Veiled Attempt' to move attention away from Fire). Footage of Local Residents marking the (Alleged) Precise Location of the Fault Line on Buildings and Pavements has been broadcast Nationwide. Ample 'Misinformation' has also been provided, with Residents believing that if they are more than 5m from the Marked Fault Line, they are safe! Unfortunately, Seismic Events do not adhere to Lines Marked on Pavements! – To an extent, the Path of a Tremor can be predicted with some accuracy – However, predictions down to 5m can be considered as 'Pushing Your Luck!'
Figure 14 A Concept Design for Prefabricated Emergency Housing (2014). Part of a submission made to NHA and HLURB which still remains 'Unacknowledged!' The submission complied with the Brief in every respect. It used RHS Sections for the Main Structure, Infilled with Lightweight Concrete Panels. An Extended Family of 9 People can be accommodated Post Disaster on an 18m2 Footprint. Although 'Temporary' every Component Part and Assembly is capable of being used in the Construction of Permanent Homes..Due to limitations (Post Disaster) on Road Infrastructure, even the Largest Components can be carried by two people, and transported on a Tricycle! Units can be extended either Formally or Informally, or can be Conjoined. Assembly takes 2-3 Days on a Pre-Prepared Raft Foundation. Each House has the option of either One or Two Bathrooms. A Solar Collector provides Hot Water for Bathing, Washing and Cleaning. A small (Expandable) Photovoltaic Electrical Installation is also provided, giving 12 VDC Lighting, and 1KW (220VAC) Small Power via an DC/AC Inverter.
The National Building Code (PD 1096) prescribes a Structural and Elemental Fire Resistance of 1 Hour for Domestic Construction up to 3 Storeys. This is attainable relatively easily, using various forms of construction. However, The NHA in a Published Report 'Philippine Government Revised Standards for Housing and Construction in View of New Normal,' (December 2014) promotes a Minimum Fire Resistance of 2 Hours (Ref: Page 9), for 22m2 Terraced or Row Houses. Here, several questions need to be answered. Viz., 1. The NHA is NOT 'The Government,' it is merely an 'Agency of Government!' Therefore, it could be argued that the Document is 'Ultra-Vires.' (Above the Law.) Page 9 of the Report also cites 'Outputs of Discussions held in November to December 2013,' However, the 'Thread' is at least 'Vague,' and has not been able to be substantiated or verified – Making it up as you go along? 2. Is a 2 Hour Fire Resistance relevant for this particular type of house? In the event of a Fire, the First Response is 'Escape!' It could be argued that in a Single Space 22m2 Dwelling, the occupants would be aware almost immediately of a Fire. Therefore, 'Escape' would be in Seconds, or at most a few Minutes! – But, Hours?
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3. Following Escape and Evacuation, the next priority is Brigade Access and Extinguishment. The Philippines does not have Coordinated Emergency Services operating via a Central 999 or 911 Regional Control Centre. In Provincial Areas (and some City Locations), Fire Brigades are manned by 'Volunteers,' coordinated by the Local Barangay (Equivalent of a Parish Council). Therefore, it could be argued that Response Times could become Protracted – However, this is unlikely to exceed 30 Minutes. (Source: Barangay San Luis Fire Brigade Antipolo: Response Log)
Figure 15 Aha! – The reason for No Acknowledgement! The Submission in Figure 14 has been taken by the 'Boffins' from NHA/HLURB and 'As if by Magic,' it now has a Reinforced Concrete Frame and Hollow Block Infill! – Because the Rules were Changed (Behind the Scenes – Post Submission) with 2 Hour Fire Resistance becoming a Design Requirement! However, the Roof on this Model has NO Fire Resistance whatsoever, and the In-Situ Reinforced Concrete Rainwater Gutters do not achieve 2 Hours, and are almost 'Impossible to Construct! – They only 'Hint' at being 'Impervious!' Yet this Model has been 'Approved!' – Accepted without thought! It falls far short of the Brief, having a 22m2 Footprint (The Maximum being set at 20m2) Furthermore, it can only accommodate 6 Persons, rather than the Minimum of 8 stipulated. Doors, Windows and a Kitchen are all 'Optional Extras!' However it could all be yours for PHP 295,000/- Lang! (US$ 6,555) – Er, No Thank You!
4. Commonsense would dictate that if a Fire occurred in the terraced situation, the adjoining properties would be evacuated as a precaution. In any event, should a fire persist for 2 Hours, Radiant Heat through the Party Walls, would be sufficient to require evacuation. Moreover, with the storage of LPG Cylinders internally, it could be argued that Radiant Heat from the affected property would be sufficient for the ignition of the LPG. There is little or no regulation of LPG Canisters, and no Compulsory Retirement after 2 Years, as in other parts of the world. 5. Even with a 2 Hour Fire Resistance the Structural Stability, Integrity, and Durability of the Building would become questionable, leading to Disproportionate Collapse of the Terrace, or at least the Collapse of the affected property – Which may be of some merit. Certainly from a Construction point of view, some Concrete Details, for the Proposed Design do not meet the 2 Hour Standard. (Ref: NHA Report Page 28 and Figure 14) 6. Despite prescribing a 2 Hour Fire Resistance, the Roof is Non-Fire Resisting! Notwithstanding London Building Act (LBA) Projecting Party Walls, an Unextinguished Fire of 2 Hours Duration (Without a Fire Rated Roof) would effectively 'Leap' from one property to the next along the Terrace.
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7. With this type of property we must also examine 'The Source of Combustion.' The most common cause will be related to Cooking and the Kitchen. However, there is no Kitchen provided! – Merely a Sink and Tiled Worktop in the Back Yard. With Cooking being done either by LPG or Pressurised Paraffin, it should be of no surprise that Gas Leaks, are the most common cause of Fire! (Source: Barangay San Luis Fire Brigade) So why was 2 Hours ever suggested? On the one hand it could be seen as Empirically Based, and 'Well Intended' – If you request 2 Hours, you are more than likely to achieve the Required 1 Hour Fire Resistance almost by default. However, if we examine the list of 'Accredited Technologies' (Ref: NHA Report Page 42 Et Seq); it can be seen that they are all 'Concrete Based!' – What a Surprise! Figure 16 The Rainwater Gutter Detail referred to in Figure 15 (Above) Firstly, it 'Fails as a Piece of Structural Design!' The Gutter is NOT Tied to the External Wall at Wall Plate Level. The Mass of the Projection, coupled with the 'Resultant Overturning Moment' will cause the Gutter to Fall! The Waterproofing can be termed 'Inadequate' as the House Face of the Gutter will Leak! – No Waterproofing! It is virtually impossible to construct this Assembly! – Even as Precast! There is NO Structural Continuity between the Wall, Gutter Assembly and Roof! – Consequently, the First Floor Wall is unrestrained! A Single Rainwater Pipe of 50mm is also 'Inadequate!' Finally, there is a Substantial Gap between the Roof Sheeting and the 'Topping Mortar!' – Roof Rat Access! What was wrong with using a Lateral Beam at Roof Plate Level, to which the Head of the External Wall could be anchored; and a Pressed Metal Gutter? QED – Cheaper, More Effective (Structurally), Waterproof, and Easier to Build! – Masonry and Roofing Trades Only! However, Despite the above, someone will have 'Approved' this detail! – Therefore, it cannot be questioned! As we see all too often 'Approved, but Fundamentally Flawed!'
The imposition of a 2 Hour Fire Resistance effectively removed other competing and viable solutions, using Construction other than Concrete! The NHA and HLURB also operate a Parrallel Code (BP 220:2008) which supposedly runs alongside the National Building Code (PD 1096:1977). The Document relates to 'Economic and Socialised Housing,' yet promotes Design Criteria that fall short of even those 'Minimum Standards' of the 1977 National Building Code. As a consequence, Practitioners and Regulators rarely know which Code to follow! The Minimal Requirements of Codes becomes the 'Level of Maximum Provision' on the part of Developers! – The Building Code does stipulate that a WC has to be provided. However, it does not specify a Cistern! – Hence the 'Pail-Flush' WC! The same applies to the Kitchen. Here, we are back in the 'Realms of Protectionism!' With Reinforced Concrete Construction it is relatively easy to increase the Structural Fire Resistance – Merely increase the Depth of Concrete Cover to Reinforcement! However, Fire Protecting Timber and Steel Structures above 1 Hour requires Specialist Design, Skilled Trades, and Expensive Materials, to be effective.
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Design to Reality One of the Initial Tenets of Seismic Design is ‘Building Form.’ Here, consideration has to be made of the 'Shape and Mass Distribution' of the Building. Obviously due cognisance has also to be made of Local Seismic History. Here, there can be substantial differences even within the same Province, or District. From this Basic Information a Structural Engineer will develop his Seismic Design. The Design will affect all elements of the Building from the Foundations, through to the Roof, and may necessitate fundamental changes in the Proposed Design, and/or Architecture. Here, it is common for the Architect, and Structural (Seismic) Engineer to work together. Once completed, all Drawings and other Documentation has to be submitted to the Local Municipality for Building Permit Approval. Here, it is often found by Architects and Engineers in Professional Practice, that the Design is reviewed neither ‘Sympathetically,’ nor 'Adequately' by the Municipality. This is due largely to a lack of Continuing Professional Development Training within Municipalities; and Codes that have changed little in over 40 Years. Additionally, Municipality Engineers are not renowned for their ability to 'Think Outside of the Box!' The National Building Code of 1977 (PD 1096) was an Enabling Act. Other Codes (Local and International) have joined it. Hence, a multiplicity of 'Interpretations and Personal Prejudices' abound! Municipality Engineers seldom ‘Question’ Code Clauses, erring towards ‘The Letter of the Law;’ rather than following the 'Spirit of The Law!' It should therefore, be of little surprise that ‘Conflicts’ occur regularly. A good example here is the reliance upon American Fire Standards (NFPA 101) in the National Fire Code (RA 9514:2008). Many Municipality Engineers jump immediately to the 'Meat in the Sandwich!' – The Technical Requirements of NFPA 101. However, and more importantly, it is the First Sentence of NFPA 101 that is overlooked all too frequently! - "This Document is a Guide!" Being a 'Performance Based Code' there are often several solutions available to solve a single problem.
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Quality of Materials and Construction? We now have a ‘Compromised Design’ going forward to Construction. This will also be ‘Interpreted’ by the Contractor, who is seeking to Maximise Profit! – Albeit at the expense of 'Quality!' Drawings, Details, and Specifications need to be 110% 'Watertight!' – And, unless ‘Supervised’ he will build precisely what he wants to build, for the Cheapest Price he can! (Note that 'Supervised' is very different to 'Inspected!') It should go without saying that ‘Quality’ will suffer if a Contractor is permitted to take a 'Sojourn into the Bargain Basement!' Hence, we return to the Ubiquitous Hollow Block; and all that it brings with it! We have already discussed the Inherent ‘Quality’ (Or ‘Lack of Quality’) related to Hollow Blocks. The Quality of Mixing, Placing and Curing of Concrete is another vitally important aspect of any Build. Ignorance on the part of Unskilled Labour then conspires with ‘Misguided Thrift’ on the part of the Contractor! The results are 'Cheap Solutions,' with questionable longevity.
Figure 17 Even with Manual Batching and Mixing a Thorough Level of Quality Control is required. This begins with comparing What was Ordered with What was Delivered! If 19mm Aggregate was Ordered, it should pass through an 19mm Sieve! Washed Sand should NOT taste of Salt! Even Basic 'Slump Tests' are still Obligatory, as are Cube Tests at 7, 14, 21, and 28 Days! As stated within the Main Text, The Ingredients are the same! – It is merely the Method of Mixing that is different!
For Domestic Construction, it will be highly unlikely that Volume Batched Ready-Mixed Concrete will be used. Firstly, it is expensive; and Secondly, Ready-Mix Plants are not aligned to the Small Builder. Neither is the Small Builder aligned to the Ready Mix Plant! – He has to pay Cash, before the event! Therefore, Concrete will at best be Mixed in an Electric, Diesel, or Manual Mixer. Alternatively, it will be Mixed by Hand, on the Ground. Strict Quality Control is essential, in terms of Materials, Labour, and Workmanship. For Structural Concrete it is recommended that Cube Tests be carried out at 7, 14, 21 and 28 Days – Even for Hand-Mixed Concrete! The 'Ingredients' are no different; they are invariably Batched by Volume. It is merely the 'Method of Mixing' that differs. In The Philippines 'Certificates' and other Regulatory Information has little or no Legal Effect! – Pure and Simple, 'It is made-up as they go along!' - So long as an 'Approver' receives a 'Financial Incentive!' 30156-D01-15061701
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Should anything be 'Questioned' at a later date, the 'Approver' will deny ever having signed anything! – Citing his signature as a 'Forgery!' (Source: Chan Robles Construction Law, Manila) Various ‘Qualities’ of Steel Reinforcement also thrive. Therefore, for New Construction an authentic ‘Mill Certificate’ should be obligatory. Inferior Grades of Steel (Emanating from PRC) use ‘Recycled Metal,’ that is of various grade and origin. Combining Steels having Dissimilar Metallurgical Content, will both initiate and accelerate Corrosion! Some will recall the Debacle of Lancia and Alfa Romeo during the late 1970s caused by Low Grade Steel exported from the Former USSR. During the Design Stages, the sizing of Columns and Beams is important, not only for Structural Integrity, but also for ‘Buildability!’ Frequently, a Contractor will ‘Attempt’ to compress the depth of a 'Designed Column' down to the thickness of the wall. However, placing Reinforcement and Concrete in a 150x150mm Column is nigh impossible! – You do not need a Builder, you need a Gynaecologist! – Tea Spoons are also required to Place the Concrete!
Figure 18 Above we can see the impracticability of the 150 x 150mm Column. The Sketch (Right) shows what we are attempting to achieve. Top Left, it becomes impossible to use 'Spacer Clips.' The Sketch (Bottom) is almost certainly what will happen, if the Reinforcement is not fixed before the Concrete is poured, or too much Concrete is poured. We all know that it does not work! – Yet it is an all too common sight!
All too frequently substitutions will be made for various types of reinforcement. Here again, the general thinking is that 'Deformed High Yield Bars' rather than 'Plain Steel' Reinforcement makes for a 'Stronger Construction.' On the one hand, Yes it Does! – However, certain elements are required to 'Move and Yield' – Particularly with Seismic Design, and the need for Ductility. Hence the specification of Plain Reinforcement, in certain locations. Substitutions, therefore must always be Approved by the Structural Engineer. Generally, Columns smaller than 200x200mm cannot be adequately reinforced and placed if executed In-Situ. Neither can they be Vibrated to remove entrained air. Even 150x150mm Precast Factory Manufactured Elements require special practices in order to ensure Stability, Integrity, Durability and Levels of Finish. If we follow the Principles of 'Confined Masonry,' it is important to recognise that it is reliant upon 'Strong Columns and Weak Beams!' However, in reality the Beams are not made deliberately weak! 30156-D01-15061701
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The Beams have to perform under Normal Loading. Further additional Lateral Reinforcement is also required to resist the effects of Horizontal Seismic Tremor. What the maxim attempts to communicate is the 'Overdesign of the Columns,' when compared to the Beams. Insubstantial Columns and Beam Connections are one of the prime causes of Failure and Building Collapse during a Seismic Event. Infilling the Blockwork is an aspect of Construction that appears to be ‘Fine in Principle!’ - The reality is somewhat different! The Hollow Blocks have to be painstakingly 'Threaded' over the Vertical Reinforcement. The blocks are bedded in Cement Mortar, and the voids filled with Concrete. In practice, only those voids that contain Steel will be filled; in an attempt to save money! – Constant and Diligent Supervision is therefore required. As the wall gets closer to the top, 'Threading' is not possible! – There is a Beam in the way! Here, there is a temptation to either cut the Vertical Reinforcement, or cut the Block, leaving it unfilled. Both practices are unacceptable! – The Head of the Wall is Unrestrained! Lateral Reinforcement, for the Hollow Block Infill, placed in the Bed Joints, has to be tied to Columns. Ideally, Starter Bars can be cast into the Column on to which the Lateral Reinforcement is tied later. This can however, be something of a 'Hit and Miss Affair!' Once Cast, the Starter Bars cannot be adjusted, and may not align with Blockwork Coursing – Leaving them 'Untied!' – Rebar in the Bed Joints, but not tied to anything, merely ensures the wall will collapse as a whole! – Rather than 'Flex' as was intended.
Figure 19
But never mind, the whole process can be covered-up with Render/Plaster, and Paint! – And, no one will know the difference! – Except during a Seismic Event, when the walls begin to fall down!
This Study is developed further in the 'Climate' Section below, and Appendix 1. Graphically, it displays where Condensation is likely to occur within a Building Structure. Climate Details relate to Dubai UAE. It does however, demonstrate that the Insidious March of Interstitial Condensation can be predicted with some accuracy! 30156-D01-15061701
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Climate! – A Further Dilemma Reference has been made already to the Climate of Manila. Indeed, due to the Archipelago Geography most of The Philippines is at risk due to a Salt-Laden Environment.
Figure 20
This Salinity is exacerbated further due to Environmental Pollution. In such instances the 'Concrete Recipe' and its Ingredients must be different, in order to ensure Stability, Integrity, Durability, and resistance to Acidic Moisture Penetration.
As far as possible we should follow the Ethos of 'Design with Climate – There is very little point in fighting it! – Climate will always win! Domestic Design in The Philippines should ideally avoid the need for Mechanical/Electrical Cooling – Note that we do not refer to this as 'Air Conditioning,' as most Domestic Cooling Machines merely 'Recirculate Air,' and have few controls.
Even within the Environs of Manila there are substantial differences in Microclimate. Antipolo City, despite being only 14 Kms from Metro-Manila, is some 90m Higher above Sea Level. Consequently, the Microclimate can be some 5°C Cooler, and Relative Humidity Levels following a much more 'Comfortable Profile.' As a result, Air Cooling is not required – Even during the Peak of Summer (March to June).
Most traditional equipment is highly inefficient. Given that Domestic Electricity Costs in The Philippines are the highest in the World, we try to negate Electrical Cooling completely. However, where this is part of a Client Brief, or unavoidable, we use Computer Modelling in order to achieve the Greatest Levels of Comfort, for Minimum Cost. Here a 'Balance' has to be struck between Capital Cost and Running Costs.
Climate is inseparable from Construction Design! – 'Should you Get it Wrong,' the consequences can be Disastrous! Here, a 'Golden Opportunity for Contractor Thrift' appears to have been lost! Marine (High Salinity) Environments has historically relied upon a GGBS Mix for Concrete. In very simple terms, the Cement Content is reduced; being replaced with Ground Pumice or Volcanic Ash – A product that The Philippines has in abundance!
We also advocate the use of 'Off-Grid' Photovoltaic Systems, in order to reduce consumption from Meralco. Presently there is much Political Posturing and 'Misinformation' being offered by Meralco and the Department of Energy. However, we take a very Pragmatic View in terms of Photovoltaic Design. Off-Grid Systems (Given the High Cost of Electricity), have a Return on Investment of 5 Years or Less – Far less than other part of the World. Meralco and the Department of Energy have 'Little to Gain and Everything to Lose' from promoting Off-Grid – In short, they begin to a lose grip on their Monopoly. Instead, Meralco and the Department of Energy are promoting 'Grid Tie,' with a 'Capped' Maximum KWHr Contribution. Here the Payback Period has been 'Engineered' to achieve 30 Years!
At a microscopic level, the fine nature of the Pumice fills the gaps between the cement particles, substantially improving its resistance to moisture penetration. The exposed Concrete Structures on Corregidor Island (Manila Bay) bear testimony to this, with some dating back to the Late 1920s and Early 1930s. Essentially, the general climate of The Philippines (For Domestic Design), creates a 'Steady State' between Internal and External Environments. Internal 'Comfort' is achieved commonly via Ceiling Fans, Natural Air Movement, and a minimal level of Mechanical/Electrical Cooling.
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Consequently, there is little to be gained from Insulating Wall Construction – Except to overcome the effects of Summertime Overheating, on South Elevations. A 'Steady State,' and No Insulation will not lead to the 'Perils of Interstitial Condensation!' (Condensation that occurs within the Wall or Roof Construction, and is largely unseen.)
Figure 21 Typhoons, Earth Tremors and Volcanic Eruptions are the main Natural Phenomena prevalent in The Philippines. However, it is highly likely that the majority of the population will never be affected by any of them. However, is more than likely that many will experience problems in terms of Secondary Effect. Typhoons bring Rain, which leads ultimately to flooding. Erecting Buildings can also have a material effect on Microclimate. For Example: A Green Field today might well be developed for Housing. It goes from being 100% Permeable to being 100% Impermeable, in a short space of time. As a result Localised Flooding can occur on the site itself. Unless there is a considered design in terms of Drainage, problems can occur outside the site, with excessive Storm Water Run-Off and Surcharging of Drainage further down the line. Consequential Damage to Microclimate can also occur when Tall Structures are aligned either side of a Wide Boulevard type road. The Buildings effectively create a Wind Tunnel. Whilst the Government of Dubai promotes High Rise Developments along Sheikh Zayed Road and Jumeira Lake Towers, it will NOT tell you about being 'Blown off your Feet!' – Or of Windows being 'Sucked from Buildings!' (Source: SkyscraperCITY)
Roofs are somewhat different – Rather than the Northern European Model of 'Retaining Heat,' Tropical Design has to 'Reject Heat' from the Sun; either by Insulation or by various means of Deflection or Shading. Construction Design is therefore, 'Turned on its Head!' In Northern Europe, Surface Condensation occurs on the Inside of Windows, in the Tropics, it appears on the Outside! – Hence the importance of locating insulation in the correct place, within the construction, and ensuring that it is the right type. Here, there is very little of a sinister nature to contend with! – It is all 'Basic Physics' and can be predicted by Calculation and Environmental Modelling! The Construction Antithesis of Plain Masonry Domestic Construction, is probably a High-Rise Office or Apartment within Metro-Manila. During the hours of Occupation, Air Cooling will be required. Immediately we have a situation having a Summertime External Temperature of 38°C and 20°C Internally. Relative Humidity will be in the order of 95% Externally, and 50% Internally. Such large differences will create Condensation. If insulated, in order to reduce Energy Costs, such Insulation has to be of the Correct Type, and in the Correct Location, in order that Interstitial Condensation is prevented; or at least occurs in a 'Safe' part of the construction, from which it can drain. Interstitial Condensation (which can also be Salinated and Acidic), will attack Structural Reinforcement, and will also degrade Concrete. It occurs within the Construction, and cannot be seen. The effects are even more insidious in that once Reinforcement Corrodes, it expands greatly, resulting in large pieces of Concrete being capable of falling from the Building!
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Cladding Panels that are 'Tied Mechanically' using Plain Steel Connectors or Ties are also vulnerable. Once corroded, an entire panel can fall! In recent years Insulated Concrete Forms (ICFs) have become another Construction Alternative. These essentially follow the notion of the Hollow Concrete Block. However, instead of being fabricated from Concrete, they are manufactured from Polystyrene. Reinforcement Steel is placed in a similar fashion, and the Void Spaces filled with Concrete as work proceeds. The System works well in the Climates of Northern Europe, however, leads to Interstitial Condensation (Within the Reinforced Concrete Core) in Tropical Climates. Additionally, the use of Insulation on the Internal Side of Construction creates a Structure of 'Low Thermal Mass.' In short this means that the Structure will not retain heat (Or Cooling – Physics regards 'Cooling' as Heat!) Consequently, spaces will lose any benefit of Mechanical/Electrical Cooling, within a short space of time – However, as a benefit they do respond to Cooling quite quickly. As already stated, one of the Prime Hazards in The Philippines is 'Fire!' Low Thermal Mass, Internally Insulated Structures such as ICFs will be susceptible to Fire Damage. Radiated and Conducted Heat from Combustion will burn Polystyrene Insulation, and also create further Smoke and Toxic Gas Hazards. Once Burned or 'Melted' the Reinforced Concrete Core will be exposed, as the Finishing Layers collapse. Renovation of an ICF Fire Damaged Property will almost certainly require Demolition and Rebuilding! Figure 22 In conclusion, the Sketch above is precisely what we are trying to avoid! A Column that does not know what it wants to be (Tied or Independent), and is impossible to construct; Blockwork that has to be 'Threaded' over Vertical Rebar; and Block Voids being filled haphazardly!
Part 1 Conclusion So, and to Conclude Part 1, we return once again to the 'Concrete Structure!' Part 2 Proposes an alternative based upon Precast Elements, and 'Known Technology!' The System has the most superb ingredients to make the 'Perfect Shepherd's Pie!' – Rather than making it from 'Dog-Meat!' - As with the Hollow Block!
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BahayTUKO Solid Confined Masonry System
PART 2 The BahayTUKO System
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BahayTUKO (Solid Confined Masonry System) Here, all of the foregoing has been addressed. A Structural Model following the Earthquake Engineering Research Institute Principles of Solid Confined Masonry has been followed. Construction Sequences follow accepted practices. Construction Specification will be dictated largely by Local Environmental, Climatic, and Seismic Factors – However, the Principles remain essentially the same. Each Component Part of the System has been designed to overcome the shortcomings of Traditional Reinforced Concrete Frame and Blockwork Infill. It is easy to build, with Components only capable of being 'Placed in the Correct Manner!' Although somewhat 'Different' it is compatible with similar Masonry Structures, and can (Subject to Structural Design) incorporate Traditional Blockwork Elements.
Figure 23 A Part Section through the First Floor, showing the Main Component Parts of the System. In Plan (Horizontally), the System used a 95 mm Module based on the Quarter Block. The Half Block is 210mm. Vertically, the System uses the same 200mm Block Module as Hollow Blocks. This can be divided further to 95mm for the Short Swastika Column Block.
Figure 24 Chases for Pipes and Conduits can be cut easily with a Grinding Disc. The Plaster Key Slot acts as a Guide. Chases are Grouted after the Conduits have been installed. Slots Coordinate with the Half Block (In Bond), and are also provided externally.
Due to the Factory Manufacture of each Component, a much 'Tighter Rein' can be kept on Quality and 'Dimensional Tolerances.' This not only improves Structural Performance (As everything Aligns), but it negates the frequent compromises that have to be overcome by Finishing Trades, due to 'Dimensional Intolerance!' In terms of Architectural Layout and Design, a Simple Logic of following a Block Module is all that is required. Blocks are the same Serial Size as Hollow Blocks, therefore Vertical Alignment and Coursing will follow accepted dimensional norms. Below is a commentary on the various elements of the BahayTUKO System, and how they work together. Viz.,
The Swastika Column Blocks These Blocks are 200mm Wide and 200mm Deep. They are available in 95mm and 200mm Depths. They are intended to remove the problems associated with placing Reinforcement and Concrete within Timber Formwork. The Blocks do not require the Reinforcement to be 'Threaded.' The Vertical Bars are incorporated 'As Work Proceeds.'
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Bent Rebar Stirrups (100% and Welded) or Stirrup Plates are incorporated at each joint. A 'Pocket' in the Block accommodates the depth of the Bar or Plate. Hence the Block Depths of 95mm and 200mm, in order to achieve closer Stirrup Spacing at the Head and Foot of the Column. It should be appreciated that the Swastika Column Blocks can be laid simultaneously with the Wall Blocks – Confined Masonry requires that the Walls and Columns 'Act Together.' Lateral Reinforcement to the Wall Blocks can again be laid 'As Work Proceeds,' and can be tied effectively and securely into the Vertical Column Reinforcement.
Solid Slotted Wall Blocks These Blocks are 400mm Long 200mm Deep, and 200mm High – The same Serial Size as Traditional Hollow Blocks. Coordinating Half Blocks are also available (195mm Long 200mm Deep, and 200mm High); as are Quarter Blocks, for infilling. Alternatively, Conventional Blockwork can be used for short 'Make-Up' Zones (Subject to Structural Design).
Figure 25 The illustration above shows the Basic Swastika Column Blocks in 95mm and 200mm Depths. Stirrup Plates or Rebar Stirrups can be used, which fit into a Recess in the Crown of the Block, and are Grouted into place. Two Sets of Blocks can be Conjoined to create a 400 x 200mm Column. In all instances the Vertical Reinforcement is accommodated As Work Proceeds. Blocks are bedded in Cement Mortar, and the Rebar Voids are Grouted with Mortar once complete.
The Blocks do not require to be 'Threaded' over Rebar! Instead, the Blocks 'Slide' into place horizontally. Note that Rebar can also be incorporated 'After' the blocks have been laid! Blocks are laid 'Opposite Hand' on alternate courses, improving the Mechanical Bonding of one course to the next. This also ensures that the Vertical Wall Reinforcement aligns with the Lateral Reinforcement (On Alternate Courses.) Note the 'Keyed Slots' on both the Internal and External Faces. These also align, from one course to the next, assisting the Execution of Work and Sequence of Work. Essentially, the 5mm Deep Slot provides a 'Bonding Key' for Plaster and Render Finishes. However, it also acts a 'Guideline' for Service Chases.
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With Conventional Hollow Blocks, the Service Chases are cut after being laid and filled, using a Cold Chisel, Bolster and Lump Hammer. The work is Tedious and Time Consuming. Frequently, the Chases are inadequate, and have to be extended by following trades – Or not extended, leading to problems for the Plastering and Finishing Teams, where the Conduits or Pipes 'Bulge-Out' from the wall! With the BahayTUKO Solid Slotted Wall Block, the 'Key Guide' is used as a guideline for a Grinding Tool. The Slot is then 'Opened' and the Conduits placed in the Recess Void. Once complete, the Slot is filled with Sand Cement Mortar. By its very nature the Solid Slotted Wall Block is considerably heavier than its 'Hollow Block Cousin!' – To ease 'Placement,' a 'Mechanical Handle-Bar' can be used for Lifting and Movement. 'Tangs' on the Lifting Bar, engage in the Conduit Slots, and the Block can be lifted safely and easily. Once 'Placed' the 'Tangs' are released, and the Lifting Bar removed.
Hourdi Lintel and Ring Beam Blocks
Figure 26 Wall Blocks are laid in Opposing Directions on alternate courses. Vertical Reinforcement is incorporated either in the Rebar Pocket, or in the Recess at Vertical Joints. Lateral Reinforcement is laid on alternate courses. Note the 'Mechanical Handle-Bar' used for lifting the blocks; and the Block being placed Horizontally, rather the Vertically over Rebar! Half Block Modules are also available.
This Technology is common in many parts of the Middle East. It avoids Time Consuming Timber Formwork, and consequential delays due to Setting and Initial Curing. Alternatively, Pre-Stressed Lintels can be used. However, a Lifting Rig will be required for Long Spans. When used as Lintels, the Hourdi Blocks will require 'Propping' from Below. However, 'Standard Timber Props' can be fabricated on site, or 'Adjustable Screw-Jack Props' can be used. The Hourdi Blocks are 'Perforated' to the underside. The Holes and Slots align with Vertical Column and Wall Reinforcement, that penetrate the Block, and connect to Continuity Steels etc. All Holes and Slots are 'Plugged' with Polystyrene. Where a Penetration is required, a Blow Torch is used to remove the Plug.
The wall is Loadbearing, therefore the Blockwork will have a Compressive Strength of 3.5 N/mm2 NHA/HLURB Requests 6.0 N/mm2 (Expressed as 3,000 Psi) which would materially affect the Ductility of the Structure. 30156-D01-15061701
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Precast Beam & Block Floor The Precast Beams are Set-Out using the 'Key Slots' in the Vertical Blockwork as a Visual Guide. Levelling Shims are used at either end to ensure Line and Level. Once Placed and Levelled, the Beams are Grouted in place. Floor Blocks are then laid between the Beams. Again due to Issues of Weight, a 'Mechanical Handle-Bar' is used for ease of Lifting and Placement. The Blocks are laid 'Dry.' Continuity Steel aligns with the Slots in the top of the Blocks. A layer of Light Steel Mesh is laid over the Completed Floor Deck, and a 25mm Structural Screed poured. Purpose-Made 'Beamfill Blocks' are provided for use at the Bearing Ends, under both the Leading and Closing Floor Blocks. Thus, 'Closing the Gap.' There is no requirement for In-Situ Concrete Infill. Once Complete, Finishes can be laid, within a 25mm Nominal Zone (8mm Cementitious Tiles laid using the 'Thick Bed' method. Or any other Method of Finish. Figure 27 The illustration shows the Hourdi Lintel and Ring Beam Modules. Once the Ring Beam has been Laid and Cast, the Precast Floor is Placed. The Module of the Wall Blocks aligns with the Floor Beams using the 'Chase Lines.'
A Plasterboard Ceiling is then laid below on 25mm Pressed Metal Lining Rails. The Lining Rails are in turn fixed to Pressed Metal Support Channels, fixed to the Underside of the Floor Blocks. No Fixings are to be made in the Underside of the Floor Beams (Shot-Firing is NOT Permitted either!) Electrical Conduits are laid in the (25mm) Lining Rail Zone, across the Ceiling Void.
Lightweight Staircase Assemblies A Traditional Timber Staircase can be installed immediately after Construction. A Timber Staircase is a High Quality Joinery Component, and should best be installed as part of the Finishing Process. Even when Protection Boards are used, substantial damage can still result, should the flight be used for access during construction.
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Alternatively a Lightweight Pre-Cast Staircase can be installed. These use a combination of Lightweight Pressed Metal Sections (Strings, Treads and Risers), together with Traditional Steel Reinforcement (Waist). The Staircase Frame is lifted into position manually, and fixed at the Foot and Head. Voids and Interstices are then filled with In-Situ Concrete, on Site. Concrete is Placed from the Face of the Flight. A 'Captive Permanent Shutter' in Cementitious Board, retains the Concrete. The Completed Staircase is ready for finishing, and can easily be installed as part of the Base Build Operations. This solution permits the Base Build Staircase Element to be used as Construction Access within the dwelling. No further protection is required.
Part 2 Conclusion Judge for Yourself! The System uses Concrete and Steel Reinforcement – No Different to the Hollow Block Model! Construction will be undoubtedly faster, with Quality being greatly improved. Secondary benefits will also accrue, due to improved Dimensional Coordination; which at least gives Finishing Trades a 'Fighting Chance!' Figure 28 The Photograph used in Figure 8 was taken through the Riser of the Pressed Metal Staircase. Once Placed, a Permanent Shutter of Cementitious Board is Screw Fixed to the Soffite. The remaining Loose Reinforcement is Placed, and Concrete Poured in Stages, through the whole Staircase Lift. Temporary Plywood Shutter Boards are required to the Risers.
Basic Structural Performance is also improved, given the Loadbearing Nature of the System – It is simply a more 'Balanced Design!' With regard to Seismic Design, it not only recognises the EERI Principles, but in many instances takes these further. The System does require further Refinement, Development, and Testing, in order to ensure that it meets targets of Structural and Seismic Performance, and also Safety in terms of the Completed Product, and also Construction.
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BahayTUKO Slotted Confined Masonry System
APPENDIX I Supplementary Technical Information
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