1. 1. . PORTAL FRAMEPORTAL FRAME Submitted by:Submitted by:-- JAHNVI GULATIJAHNVI GULATI B.ARCH (AR)B.ARCH (AR) 44THTH YEAR, 8YEAR, 8THTH SEM.SEM.
2. 2. . INTRODUCTIONINTRODUCTION PORTAL FRAMEPORTAL FRAME Portal frames are the most commonly usedPortal frames are the most commonly used structural forms for singlestructural forms for single--storeystorey industrial structures. They are constructedindustrial structures. They are constructed mainly using hotmainly using hot--rolled sections, supportingrolled sections, supporting the roofing and side cladding via coldthe roofing and side cladding via cold--formedformed purlins and sheeting rails. They may alsopurlins and sheeting rails. They may also be composed of tapered stanchions and raftersbe composed of tapered stanchions and rafters fabricated from plate elements. Portal frames offabricated from plate elements. Portal frames of lattice members made of angles or tubes arelattice members made of angles or tubes are also common, especially in the case of longeralso common, especially in the case of longer spans.spans. Generally, the centreGenerally, the centre--toto--centre distancecentre distance between frames is 6 to 7.5m, with eaves heightbetween frames is 6 to 7.5m, with eaves height ranging from 6ranging from 6 --15 m.15 m. Normally, larger spacing of frames is used in theNormally, larger spacing of frames is used in the case of taller buildings, from the point ofcase of taller buildings, from the point of economy.economy. MomentMoment--resisting connections are to be providedresisting connections are to be provided at the eaves and crown to resist lateral andat the eaves and crown to resist lateral and gravity loadings.gravity loadings. 11
3. 3. . INTRODUCTIONINTRODUCTION PORTAL FRAMEPORTAL FRAME 22
4. 4. . INTRODUCTIONINTRODUCTION PORTAL FRAMEPORTAL FRAME 33 The stanchion bases may behave asThe stanchion bases may behave as either pinned or fixed, depending uponeither pinned or fixed, depending upon rotational restraint provided by therotational restraint provided by the foundation and the connection detailfoundation and the connection detail between the stanchion and foundations.between the stanchion and foundations. Portal frames can be used in timberPortal frames can be used in timber based commercial and industrialbased commercial and industrial building construction with clear spans ofbuilding construction with clear spans of 15 to 30 metres.They provide large15 to 30 metres.They provide large clear spans and good height clearanceclear spans and good height clearance for use in a range of applications,for use in a range of applications, including:including: warehouses and factories,warehouses and factories, commercial buildings,commercial buildings, churches,churches, sporting venuessporting venues rural sheds, etcrural sheds, etc..
5. 5. . INTRODUCTIONINTRODUCTION PORTAL FRAMEPORTAL FRAME Timber portal frames are cost effective, easilyTimber portal frames are cost effective, easily accommodate additional lighting, plumbing, etcaccommodate additional lighting, plumbing, etc and can be erected quickly. The overalland can be erected quickly. The overall appearance is also aesthetically pleasing.appearance is also aesthetically pleasing. Timber portal frames are particularly suitable forTimber portal frames are particularly suitable for use in high visual impact applications eguse in high visual impact applications eg churches, halls, or potentially corrosivechurches, halls, or potentially corrosive environments eg swimming pool enclosures,environments eg swimming pool enclosures, buildings housing chemical manufacturer andbuildings housing chemical manufacturer and storage, tanneries, etc. Portal frames may bestorage, tanneries, etc. Portal frames may be made from sawn timber, Glulam, LVL andmade from sawn timber, Glulam, LVL and plywood webbed beams. The connections carryplywood webbed beams. The connections carry significant moments and must have bothsignificant moments and must have both strength and stiffness to be effective.Timberstrength and stiffness to be effective.Timber portal framed buildings may be clad withportal framed buildings may be clad with conventional metal, or fibre cement cladding, asconventional metal, or fibre cement cladding, as is common for warehouses and factories, oris common for warehouses and factories, or with timber products such as plywood orwith timber products such as plywood or weatherboards.For other commercialweatherboards.For other commercial applications, cavity brick, brick veneer, concreteapplications, cavity brick, brick veneer, concrete tilttilt--up or concrete blockup or concrete block--work may be requiredwork may be required for fire isolation or compliance with local buildingfor fire isolation or compliance with local building regulations.regulations. 44
6. 6. . INTRODUCTIONINTRODUCTION PORTAL FRAMEPORTAL FRAME Because of these very strong and rigid jointsBecause of these very strong and rigid joints some of the bending moment in the rafters issome of the bending moment in the rafters is transferred to the columns. This means that thetransferred to the columns. This means that the size of the rafters can be reduced or the spansize of the rafters can be reduced or the span can be increased for the same size rafters.can be increased for the same size rafters. This makes portal frames a very efficientThis makes portal frames a very efficient construction technique to use for wide spanconstruction technique to use for wide span buildings.buildings. Portal frame construction is therefore typicallyPortal frame construction is therefore typically seen inseen in warehouseswarehouses,, barnsbarns and other placesand other places where large, open spaces are required at lowwhere large, open spaces are required at low cost and a pitched roof is acceptable. claddingcost and a pitched roof is acceptable. cladding with cavity masonry work to the bottom 2m of thewith cavity masonry work to the bottom 2m of the wall to provide security and impact resistance.wall to provide security and impact resistance. The lightweight cladding would be carried onThe lightweight cladding would be carried on sheeting rails spanning between the columns ofsheeting rails spanning between the columns of the portal frames.the portal frames. 55
7. 7. . PORTAL FRAMEPORTAL FRAME Portal frames are made in a variety of shapesPortal frames are made in a variety of shapes and sizes. There are generally 3 types of portaland sizes. There are generally 3 types of portal frames :frames :-- Steel portal frameSteel portal frame Timber portal frameTimber portal frame Concrete portal frameConcrete portal frame They are usually made from steel, but canThey are usually made from steel, but can also be made from concrete or timber. The portalalso be made from concrete or timber. The portal structure is designed in such a way that it has nostructure is designed in such a way that it has no intermediate columns, as a result large openintermediate columns, as a result large open areas can easily be created within the structure.areas can easily be created within the structure. Portal Frames are generally used for singlePortal Frames are generally used for single storey construction which require a largestorey construction which require a large unobstructed floor space.unobstructed floor space. 66 TYPES OF PORTAL FRAMETYPES OF PORTAL FRAME
8. 8. . STEEL PORTAL FRAMESTEEL PORTAL FRAME PORTAL FRAMEPORTAL FRAME The early use of the rigid portal frame coincidedThe early use of the rigid portal frame coincided with the introduction of a wide range of a coldwith the introduction of a wide range of a cold formed, profiled steel sheets for roofing, whichformed, profiled steel sheets for roofing, which could be fixed at a low pitch and be weathercould be fixed at a low pitch and be weather tight. Longtight. Long--span portal frames may have a pinspan portal frames may have a pin-- joint connection at the ridge to allow somejoint connection at the ridge to allow some flexure between the rafters of the frame whichflexure between the rafters of the frame which are pinare pin--jointed to foundation bases to allowjointed to foundation bases to allow flexure of posts due to spread under load.flexure of posts due to spread under load. For economy in the use of a standard section,For economy in the use of a standard section, short and mediumshort and medium--span steel portal frame s arespan steel portal frame s are oftn fabricated from one mildoftn fabricated from one mild--steel Isteel I--section forsection for both rafters and posts, with the rafters welded toboth rafters and posts, with the rafters welded to the posts without any increase in depth at thethe posts without any increase in depth at the knee.knee. ShortShort--span portal frames may be fabricated offspan portal frames may be fabricated off site as one frame. Mediumsite as one frame. Medium--spanspan portal framesportal frames are generally fabricated in two halves for ease ofare generally fabricated in two halves for ease of transport and are assembled on site with boltedtransport and are assembled on site with bolted connections of the rafters at the ridge, with highconnections of the rafters at the ridge, with high strength friction gripstrength friction grip.. 77
9. 9. . STEEL PORTAL FRAMESTEEL PORTAL FRAME PORTAL FRAMEPORTAL FRAME AdvantagesAdvantages Speed and ease of erectionSpeed and ease of erection Building can be quickly closed in and madeBuilding can be quickly closed in and made water tight.water tight. Framework prefabricated in a workshop and notFramework prefabricated in a workshop and not affected by weather.affected by weather. Site works such as drainage, roads etc can beSite works such as drainage, roads etc can be carried out until framework is ready for erection.carried out until framework is ready for erection. No weather hold up during erecting theNo weather hold up during erecting the framework.framework. Connected together in factories by welding andConnected together in factories by welding and site connections should be bolted.site connections should be bolted. DisadvantagesDisadvantages Although steel is incombustible it has a poorAlthough steel is incombustible it has a poor resistance to fire as it bends easily when hot.resistance to fire as it bends easily when hot. Subject to corrosionSubject to corrosion 88
10. 10. . PREPRE--CAST REINFORCED CONCRETE FRAMECAST REINFORCED CONCRETE FRAME PORTAL FRAMEPORTAL FRAME For several years following the end ofFor several years following the end of the second world war(1945) there was athe second world war(1945) there was a considerable shortage of structural steelconsiderable shortage of structural steel in this country and it was then that thein this country and it was then that the reinforced concrete portal frames camereinforced concrete portal frames came into common use for agricultural,into common use for agricultural, storage, factory, and other singlestorage, factory, and other single-- storeyed buildings.storeyed buildings. a limited range of standard, prea limited range of standard, pre--castcast reinforced concrete portal frames wasreinforced concrete portal frames was supplied for the economic benefit ofsupplied for the economic benefit of repitetive casting in standard mouldsrepitetive casting in standard moulds and close control of mixing, placing andand close control of mixing, placing and compaction of concrete that is possiblecompaction of concrete that is possible in factory conditions.in factory conditions. 99
11. 11. . TYPES OF CONCRETE PORTAL FRAMETYPES OF CONCRETE PORTAL FRAME PORTAL FRAMEPORTAL FRAME Symmetrical pitch reinforcedSymmetrical pitch reinforced concrete portal frame constructionconcrete portal frame construction This the most structurally efficient and mostThis the most structurally efficient and most commonly used type of concrete portal frame.commonly used type of concrete portal frame. it has been used for factories, warehouses,it has been used for factories, warehouses, barns, sheds and singlebarns, sheds and single--storey places ofstorey places of assembly.the slope of the rafters and spacing ofassembly.the slope of the rafters and spacing of purlins and sheeting rails is usually arranged topurlins and sheeting rails is usually arranged to suit fibre cement or profiled steel sheeting.suit fibre cement or profiled steel sheeting. North light preNorth light pre--cast reinforcedcast reinforced concrete portal frame constructionconcrete portal frame construction The most economical span for this profile ofThe most economical span for this profile of frame is up to about 9.0 to minimise the volumeframe is up to about 9.0 to minimise the volume of roof space inside the frames and to avoid theof roof space inside the frames and to avoid the large sections of frame that would be necessarylarge sections of frame that would be necessary with greater spans. The southwith greater spans. The south--facing slope isfacing slope is pitched at 22 degrees and the northpitched at 22 degrees and the north--facing slopefacing slope at 60 degrees to the horizontal.at 60 degrees to the horizontal. 1010
12. 12. . PREPRE--CASTREINFORCED CONCRETE FRAMECASTREINFORCED CONCRETE FRAME PORTAL FRAMEPORTAL FRAME AdvantagesAdvantages There was a ready supply of a limited range ofThere was a ready supply of a limited range of standard frames that could rapidly bestandard frames that could rapidly be transported, erected, and finished at antransported, erected, and finished at an economic cost.economic cost. they require no maintainance during the usefulthey require no maintainance during the useful life of the building.life of the building. it has a better resistance to collapse duringit has a better resistance to collapse during fires than an unprotected steel frames.fires than an unprotected steel frames. economy of section area gained by the use ofeconomy of section area gained by the use of the plastic method of design in the design ofthe plastic method of design in the design of steel frames is considerably less with reinforcedsteel frames is considerably less with reinforced concrete.concrete. cover of concrete to the steel reinforcement tocover of concrete to the steel reinforcement to inhibit rust and give protection during fires.inhibit rust and give protection during fires. DisadvantagesDisadvantages they have to be formed in standard sizethey have to be formed in standard size moulds, for the sake of economy, there is only amoulds, for the sake of economy, there is only a limited range of sizes.limited range of sizes. 1111
13. 13. . TIMBER PORTAL FRAMETIMBER PORTAL FRAME PORTAL FRAMEPORTAL FRAME Combinations of slender timber sectionsCombinations of slender timber sections glued, or glued or nailed together, areglued, or glued or nailed together, are used in portal frames for mediumused in portal frames for medium--andand longlong--span roofs for such buildings asspan roofs for such buildings as churches, assembly halls, sports hallschurches, assembly halls, sports halls and other singleand other single--storey structures wherestorey structures where the timber portal frames are exposed forthe timber portal frames are exposed for appearance sake.appearance sake. 1212
14. 14. . TYPES OF TIMBER PORTAL FRAMETYPES OF TIMBER PORTAL FRAME PORTAL FRAMEPORTAL FRAME SymmetricalSymmetrical--pitch glued laminatedpitch glued laminated timber portaltimber portal These portal frames are usually fabricated in twoThese portal frames are usually fabricated in two sections for ease of transport and are boltedsections for ease of transport and are bolted together at the ridges. These comparativelytogether at the ridges. These comparatively expensive portal frames are spaced fairly widelyexpensive portal frames are spaced fairly widely apart to support timber or steel purlins which canapart to support timber or steel purlins which can be covered with any of the sheet materials,be covered with any of the sheet materials, slates or tiles.slates or tiles. Flat gluedFlat glued--andand--nailed timber portalnailed timber portal The flat portal frame is designed for the mostThe flat portal frame is designed for the most economic use of timber glued together with theeconomic use of timber glued together with the top and bottom booms of glued laminate withtop and bottom booms of glued laminate with web stiffners. The portal frames are widelyweb stiffners. The portal frames are widely spaced to support metal decking on the roof andspaced to support metal decking on the roof and profiled sheeting on the walls.profiled sheeting on the walls. 1313
15. 15. . TIMBER PORATL FRAMETIMBER PORATL FRAME PORTAL FRAMEPORTAL FRAME AdvantagesAdvantages Timber has a natural resistance to fungalTimber has a natural resistance to fungal decay.decay. insect attack can be prevented by impregnatinginsect attack can be prevented by impregnating timber with insecticide preservative.timber with insecticide preservative. timber, which is a combustible material, is nottimber, which is a combustible material, is not easy to ignite in the sizes usual to buildings.easy to ignite in the sizes usual to buildings. Once ignited, timber burns very slowly andOnce ignited, timber burns very slowly and forms a protective layer of charcoal on itsforms a protective layer of charcoal on its surface which insulates the remainder from thesurface which insulates the remainder from the worst effects of fire.worst effects of fire. the surface of soft wood timber can be treatedthe surface of soft wood timber can be treated with flame retardants to achieve necessary ratewith flame retardants to achieve necessary rate of flame spread.of flame spread. 1414
16. 16. INTERNAL OUTLINE OF THE PORTAL FRAMEINTERNAL OUTLINE OF THE PORTAL FRAME PORTAL FRAMEPORTAL FRAME 1515 clear unobstructed floorclear unobstructed floor area available.area available. With single storey buildingsWith single storey buildings natural lighting is gained bynatural lighting is gained by placing clear sheets in roofplacing clear sheets in roof layout.layout. These sheets will run fromThese sheets will run from eaves to ridge at suitableeaves to ridge at suitable intervals.intervals.
17. 17. SHEETINGSHEETING PORTAL FRAMEPORTAL FRAME 1616 A high percentage of roofsA high percentage of roofs are covered with compositeare covered with composite profile metal sheets with aprofile metal sheets with a coloured external skin.coloured external skin. These composite sheetsThese composite sheets have approximately 50mmhave approximately 50mm of insulation sandwichedof insulation sandwiched between two thin metalbetween two thin metal sheets or aluminium sheets.sheets or aluminium sheets. Coated steel is lowest inCoated steel is lowest in cost but limited in life due tocost but limited in life due to the durability of the finish.the durability of the finish. Aluminium develops its ownAluminium develops its own protective film. Profile sheetsprotective film. Profile sheets are quick to erect, dismantleare quick to erect, dismantle and repair.and repair. Wall panelsWall panels
18. 18. BASE JOINTBASE JOINT PORTAL FRAMEPORTAL FRAME 1717 Legs of portal frameLegs of portal frame connected with theconnected with the base of foundation.base of foundation.
19. 19. RIDGE JOINTRIDGE JOINT PORTAL FRAMEPORTAL FRAME 1818 ridge joint or apex joint. wedge shaped pieces called gusset pieces to strengthen and increase the bolt area.
20. 20. KNEE JOINTKNEE JOINT PORTAL FRAMEPORTAL FRAME 1919 knee joint must be strong toknee joint must be strong to support the roof loads andsupport the roof loads and prevent bending.prevent bending.
21. 21. DIGONAL BRACINGDIGONAL BRACING PORTAL FRAMEPORTAL FRAME 2020 DiagonalDiagonal bracing forbracing for strengtheningstrengthening
22. 22. EXTERNAL WALL DETAILEXTERNAL WALL DETAIL PORTAL FRAMEPORTAL FRAME 2121 claddingcladding brickworkbrickwork