LIFTING CALCULATION METHOD

Transcription

1 LIFTING CALCULATION METHOD

2 INDEX STRESS DETERMINATION ON SLEEVES, SPHERICAL HEAD ANCHORS AND FLAT HEAD ANCHORS 1. WEIGHT OF PRECAST UNIT FORMWORK ADHESION DYNAMIC FACTOR ASYMMETRICAL LOAD DISTRIBUTION SPREAD ANGLE FACTOR COUNTING LOAD BEARING ANCHORS DETERMINATION OF TOTAL LOAD F TOT DETERMINATION OF ANCHOR LOAD F CALCULATION EXAMPLES: A. FLOOR ELEMENT- SLAB... B. DOUBLE-T BEAM... C. FACADE ELEMENT... D. VERTICALLY PREFABRICATED BEAMS AXIAL LIFTING... E. VERTICALLY PREFABRICATED BEAMS INCLINED LIFTING

3 STRESS DETERMINATION ON SLEEVES, SPHERICAL HEAD ANCHORS AND FLAT HEAD ANCHORS The achor load capacity depeds o multiplefactors such as: Deadweight of the precast cocrete elemet G Adhesio to the mould Load directio, liftig agle Number of load bearig achors Edge distace ad spacig of the achors Cocrete stregth at the time of operatig: liftig or trasportig Embedded depth of the achor Dyamic forces Reiforcemet arragemet 1. WEIGHT OF PRECAST UNIT Prefabricated elemets are composed of a higher cocetratio of reiforcig elemets. Total weight G of the precast reiforced cocrete elemet is determied usig a specific weight of: ρ= 25 kn/m³. 2. FORMWORK ADHESION G = ρ x V V = L x l x g V : volume of precast (m³) L : legth (m) l : width (m) g : thickess (m) Adhesio forces betwee mould ad cocrete deped o the type of mould used. Formwork adhesio Ha is calculated through the followig equatio: Ha = q x A (kn) A : area of cotact betwee the mould ad the cocrete uit whe startig to lift. q : Formwork adhesio factor. q = 1 kn/m² (for oiled steel mould). q = 2 kn/m² (for varished timber mould). q = 3 kn/m² (for rough timber mould). doubles ervures : Ha = 2 x G Special case : For T- slabs, formwork adhesio is superior to average. A estimate ca be made by multiplyig the precast elemet weight: H a = 2 x G (double -T slabs) H a = 3 x G (ribbed elemets ) H a = 4 x G (coffered elemets) 3

4 3. DYNAMIC FACTOR Whe the movemet of the precast uit is performed by liftig gear, dyamic forces that deped o the liftig gear used, appear. The liftig classes are described i DIN Liftig load coefficiet f at liftig speed vh Liftig class Up to 90 m/mi > 90 m/mi H1 1,1 + 0,002 vh 1,3 H2 1,2 + 0,004 vh 1,6 H3 1,3 + 0,007 vh 1,9 H4 1,4 + 0,009 vh 2,2 Liftig factor f is the acceleratio factor. Whe liftig ad carryig precast elemets, the liftig load has to be multiplied by the f factor. Class is determied by the selected liftig system (for example, class H1 for a bridge crae, class H4 for a fork-lift truck o a ueve groud). The dyamic factor depeds o the meas used for the liftig. These factor depedig o the type of liftig system are listed o the table below. Liftig equipmet Liftig load coefficiet f Tower crae ad fixed crae 1,2 * Mobile crae 1,4 * Liftig ad trasportig o flat groud 2-2,5 Liftig ad trasportig o ueve terrai 3-4 * Lower values may be appropriate i precast plats if special arragemets are made. For craes with precisio liftig, such as those i maufacturig plats the liftig load coefficiet is f = I the precast factory: for de-mould f = 1.1 for pitch ad trasport f = 1.3 O site: for pitch/trasport/istall f = 1.5 whe trasportig suspeded precast elemets over ueve terrai, the liftig load coefficiet used is f > 2. 4

5 4. ASYMMETRICAL LOAD DISTRIBUTION The load of each achor depeds o the embedded positio of the achor i the precast uit ad also o the trasportig mode. F a = F tot x b (a + b) F b = F tot x a (a + b) F tot : Total load Note: To avoid tiltig of the uit durig trasport, the load should be suspeded from the liftig beam such that its cetre of gravity is directly below the crae hook. 5. SPREAD ANGLE FACTOR The cable agle ß is determied by the legth of the suspedig cable. We recommed that, if possible, ß should be kept to ß 30. The tesile force o the achor is icreased with a spread agle factor z. Note : If o liftig beam is used durig trasport, the achor must be embedded symmetrically to the load. F = z x F tot where : z = 1 spread agle factor. cos ß : umber of load bearig achors = 2 x ß Cable agle ß Spread agle factor z 0 1,00 7,5 1,01 15,0 1,04 22,5 1,08 30,0 1,16 37,5 * 1,26 45,0 * 1,41 * preferred ß 30 a = d/2 Ratio a/b Agle (degree α) Spread agle factor 0,000 < a/b < 0,259 0 < α < 30 1,04 0,259 < a/b < 0, < α < 45 1,08 0,383 < a/b <0, < α < 60 1,16 0,500 < a/b <0, < α < 75 1,26 0,608 < a/b <0, < α < 90 1,41 5

6 6. COUNTING LOAD BEARING ANCHORS = 3 = 3 = 2 = oly 2 two das cette situatio achors take seulemet deux douilles over the ou load bearig acres supportet la charge. = 2 = 2 = 2 = 2 = 4 = 4 = 4 = 4 The compesated liftig sligs esure equal load distributio. E utilisat des câbles de levage e combiaiso avec ue pièce de compesatio o assure ue distributio égale des charges. A perfect static E utilisat weight u paloier distributio équilibré ca sur be 2 obtaied paires through the d acre use of disposées a liftig symétriquemet, beam ad two la pairs charge of achors set est out égalemet symmetrically. distribuée sur les quatre douilles ou acres. = 4 A perfect static weight distributio ca be obtaied usig a crossed spreader beam, which avoids agled pull. 6

7 7. DETERMINATION OF TOTAL LOAD F TOT Total load of precast uit for calculatig the achor is determied through the followig equatio: Whe de-mould F tot = G + Ha Whe pitchig F tot = G 2 Whe de-mould ad pitchig F tot = (G + Ha) 2 Whe trasportig F tot = G 8. DETERMINATION OF ANCHOR LOAD F The load o each load bearig achor is calculated with the followig formula: Whe de-mould F = (F tot x f x z) = (G + Ha) x f x z Whe pitchig F = (F tot x f x z) = (G/2 x f x z) Whe de-mould ad pitchig F = (F tot x f x z) = [(G + Ha)/2] x z) Durig tiltig, the cocrete elemet remais supported o the groud, oly the half of the forces have to be take ito accout. I the situatio of pitchig, load carryig capacity of sockets ad achors is limited to 50% of the axial load. Whe liftig F = (F tot x f x z) = (G x f x z) CALCULATION EXAMPLES A. FLOOR ELEMENT Geeral dates Symbol De-mould Mout Cocrete stregth at de-mould [N/mm² ] 20 Cocrete stregth o site [N/mm² ] 45 Weight for elemet [kn] G Mould area [m ²] A 10 Cable agle factor at de-mould (ß = 15,0 ) z 1,04 Cable agle factor o site (ß = 30,0 ) z 1,16 Liftig load coefficiet at de-mould f 1,3 Liftig load coefficiet o site f 1,3 Formwork adhesio factor [kn/m²] q 1,0 Achor umber for de-mould 4 Achor umber for trasport o site 4 7

8 SLAB: Dimesios: 5,00 x 2,00 x 0,20 (m³) Cocrete stregth class B45 Cocrete stregth at de-mould 20 N/mm² Weight : G= V x ρ G= 5,00 x 2,0 x 0,2 (m³) x 25 (kn/m³) = 50 kn Achor for de-mould, for trasport ad motage. SITUATION AT PRECAST FACTORY: The elemet will be take out of the oiled steel formwork with a portal crae. There is work with a liftig beam to prevet that the agle to the cocrete becomes smaller tha 75º. The used cable agle factor will be z=1,04. Will also be take ito accout: a liftig load factor f=1,3. SITUATION AT BUILDING SITE: The elemet will be lift with the aid of a turig crae. There is work with 2 clutches ad liftig beam to prevet that the agle to the cocrete becomes smaller tha 60º. The cable agle factor that must be used is z =1,16. Will also be take ito accout: a liftig load factor of f =1,3 DETERMINATION OF THE LIFTING FORCE F PER ANCHOR: At precast factory : Ha = q x A= 1,0 x 5 x 2 = 10 kn Force per achor: F = (G + Ha) x f x z = ( ) x 1,3 x 1,04 = 20,28 kn 4 At buildig site : Force per achor: F = (G x z x f) = 50x 1,16 x 1,3 = kn 4 CONCLUSION: The floor elemet ca be lifted with 4 T-Slot-achors; Type T i utreated, hot dip galvaized or i stailess carbo steel. Chose positios : Legth directio: 1/5 of the legth = 1,00 m from the edge. Trasverse directio: 30% of the width = 0,50 m from the edge. 8

9 B. DOUBLE-T BEAM Load capacity whe liftig ad trasportig at the maufacturig plat. Cocrete stregth whe de-mould 25 N / mm² Cable agle ß = 30.0 Spread agle factor z = 1.16 Liftig load coefficiet whe trasportig f = 1.3 Liftig load coefficiet whe de-mould f = 1.1 Achor umber = 4 L = 850 cm A1 = 10 x 300 (cm²) A1 = 0,1 x 3 ( m²) ρ= 25 kn/m³ A2 = [(35+25) x 30]/2 (cm²) A2 = (0,35+0,25) x 0,3 = (0,6 x 0,3) = 0,09 = 0,3² (m²) 2 2 Weight : G= V x ρ = (A x L) x ρ = (A1+A2 x 2) x L x ρ G = [(0,3 + 0,3²) x 2] x 8.5 (m³) x 25 (kn/m³) = 102 kn Formwork adhesio : Ha = 2 x G = 204 kn Total load Ftot : Ha + G = 204 kn kn = 306 kn Load per achor whe de-mould. F = F tot x f x z = 306 x 1,16 x 1,1 = 97,61 kn 4 Load per achor whe trasportig F = F tot x f x z = 102 x 1.16 x 1.3 = kn 4 USE 4 ANCHORS ALLOWABLE LOAD > 98 KN. 9

10 C. FACADE ELEMENT Dimesios : 5,00 x 2,00 x 0,20 (m3) 4 T-Slot-achors for de-mould 2 T-Slot-achors for pitchig, trasport ad moutig ρ= 25 kn/m³ Cocrete stregth class B45 Stregth at de-mould 20 N/mm² Weight : G= V x ρ G = 5,0 x 2,0 x 0,2 (m³) x 25 (kn/m³) = 50 kn Geeral date Symbol De-mould Pitchig Mout Cocrete stregth at de-mould [N/mm² ] Cocrete stregth o site [N/mm² ] 45 Weight for elemet [kn] G Mould area [m²] A 10 Spread agle factor at de-mould (ß = 15,0 ) z 1,04 Spread agle factor at pitchig (ß = 0.0 ) z 1,0 Spread agle factor o site (ß = 30,0 ) z 1,16 Liftig load coefficiet at de-mould f 1,3 Liftig load coefficiet at pitchig f 1,3 Liftig load coefficiet o site f 1,3 Formwork adhesio factor [kn/m²] q 1,0 Achor umber for de-mould 4 Achor umber for trasport o site 2 10

11 SITUATION AT PRECAST FACTORY: The elemet will be take out of the oiled steel formwork with a portal crae. I free storage the facade elemet will be brought to a vertical positio. I the meatime, the elemet is brought i a vertical positio, there is worked with a liftig beam to prevet that the agle to the cocrete becomes smaller tha 75º (ß = 15,0 ). Hereby the elemet still rests o the floor so that the T- Slot-achors oly bear half of the weight. Oly whe the elemet is i a vertical positio it ca be lifted ad the T-Slot-achors will be loaded with the full weight. That is why the brigig of the elemet ito a vertical positio is ot a ormative loadig. Also whe de-mould ad directly brigig ito a vertical positio with the aid of 2 T- Slot-achors to the frot side will ot give a ormative loadig as well. While liftig with a liftig beam: The agle to the cocrete is about 90º (ß = 0 ), the used T-Slot-achor spread agle factor will be z=1,0. Will also be take ito accout: a liftig load factor f=1,3. SITUATION AT BUILDING SITE: The elemet will be lifted with the aid of a turig crae. There is worked with 2 clutches ad a liftig beam to prevet that the agle to the cocrete becomes about 60º (ß = 30,0 ). The used spread agle factor will be z=1,16. Will also be take ito accout: a liftig load factor of f=1,3. DETERMINATION OF THE LIFTING FORCE F PER ANCHOR: At precast factory : Ha = q x A = 1,0 x 5 x 2 = 10 kn Force per achor: F = (G + Ha) x f x z = ( ) x 1,3 x 1,04 = 20,28 kn 4 At precast factory - pitchig : Force per achor: F = (G/2 x f x z) = 50/2 x 1,3 x 1,0 = 16,25 kn 2 At buildig site : Force per achor: F = (G x f x z) = 50 x 1,3 x 1,16 = 37,70 kn 2 The floor elemet ca be lifted with 4 T-Slot-achors; Type T i utreated, hot dip galvaized or i stailess carbo steel. The facade elemet ca be lifted with 2 T-Slot-achors type T i utreated, hot dip galvaized or i stailess carbo steel. Chose positios : Legth directio: ca. 1/5 of the legth = 1,00 m from the edge. Trasverse directio: 1/4 of the legth = 0,50 m from the edge. 11

12 D. VERTICALLY PREFABRICATED BEAMS AXIAL LIFTING Dimesios : 5,00 x 1,00 x 0,40 (m3) 2 T-Slot-achors for de-mould 2 T-Slot-achors for pitchig, trasport ad moutig ρ= 25 kn/m³ Cocrete stregth class B45 Stregth at de-mould 15 N/mm² Weight : G= V x ρ G = 5,0 x 1,0 x 0,4 (m³) x 25 (kn/m³) = 50 kn Geeral dates Symbol De-mould Mout Cocrete stregth at de-mould [N/mm² ] Dimesios : 5.00 x 1.00 x 0.20 m³ 15 Cocrete stregth o site [N/mm² ] 45 Weight for elemet [kn] G 50 Mould area [m ²] A 2 Spread agle factor at de-mould (ß = 0.0 ) z 1,0 Spread agle factor o site (ß = 0.0 ) z 1,0 Liftig load coefficiet at de-mould f 1,3 Liftig load coefficiet o site f 1,3 Formwork adhesio factor [kn/m²] q 3,0 Achor umber for de-mould 2 Achor umber for trasport o site 2 SITUATION AT PRECAST FACTORY: The prefabricated elemet is lifted from the rough timber oiled mould with a tower crae ad usig 2 achors. At liftig is used a liftig beam to prevet that the agle to the cocrete becomes smaller tha 90º. The agle to the cocrete is about 90º (ß = 0 ). The adhesio to mould factor is q=3. Spread agle factor will be 1,00. Will also be take ito accout: liftig load factor = 1,3. 12

13 DETERMINATION OF THE LIFTING FORCE F PER ANCHOR: At precast factory : Ha = q x A = 3,0 x 5 x 2 = 6 kn Force per achor: F = (G + Ha) x f x z = (50 + 6) x 1,3 x 1,0 = 36,4 kn 2 At buildig site : Force per achor: F = (G x f x z) = 50 x 1,3 x 1,0 = 32,5 kn 2 The situatio at the prefab factory is for the choice of the loadig class ormative T-Slot-achor: T -50 kn. CONCLUSION : The floor elemet ca be lifted with 2 T-Slot-achors type T i utreated, galvaized or i stailess carbo steel. Chose positios : Legth directio: 1/5 of the legth = 1,00 m from the edge. Trasverse directio: i the middle of the material thickess. E. VERTICALLY PREFABRICATED BEAMS INCLINED LIFTING Dimesios : 5,00 x 1,00 x 0,40 (m3) 2 T-Slot-achors for de-mould 2 T-Slot-achors for pitchig, trasport ad moutig ρ= 25 kn/m³ Cocrete stregth class B45 Stregth at de-mould 15 N/mm² Weight : G= V x ρ G = 5,0 x 1,0 x 0,4 (m³) x 25 (kn/m³) = 50 kn 13

14 Geeral dates Symbol De-mould Mout Cocrete stregth at de-mould [N/mm² ] 15 Cocrete stregth o site [N/mm² ] 45 Weight for elemet [kn] G 50 Mould area [m ²] A 2 Cable agle factor at de-mould (ß = 30.0 ) z 1,16 Cable agle factor o site (ß = 30.0 ) z 1,16 Liftig load coefficiet at de-mould f 1,3 Liftig load coefficiet o site f 1,3 Formwork adhesio factor [kn/m²] q 3 Achor umber for de-mould 2 Achor umber for trasport o site 2 SITUATION IN THE PREFAB FACTORY: The prefabricated elemet is lifted from the rough timber oiled mould with a tower crae ad usig 2 achors. At brigig i a vertical positio there is worked with a sprig that is used with a top agle smaller tha 60º (ß = 30,0 ).The used cable agle factor will be 1,16. Will also be take ito accout: Liftig load factor f= 1,3. The adhesio to mould factor is q=3. SITUATION AT THE BUILDING SITE: O site the elemet is lifted with a tower crae at a agle ß = 30,0. I this case the cable agle factor z=1,16 ad the liftig load factor is f=1,3. DETERMINATION OF THE LIFTING FORCE FPER ANCHOR: I the prefab factory: Ha = q x A = 3 x 5 x 0,4 = 6 kn Force per achor: F = (G + Ha) x f x z = (50 + 6) x 1,3 x 1,16 = 42,22 kn 2 At the buildig site: Force per achor: F = (G x f x z) = 50 x 1,3 x 1,16 = 37,70 kn 2 The situatio at the prefab factory is for the choice of the loadig class ormative T-Slot-achor: T -50 kn. Chose positios: Legth directio: 1/5 of the legth = 1,00 m from the edge. Trasverse directio: i the middle of the material thickess. 14

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