ARMATA To prevent punching failure of concrete slabs. Version: AE, SA 08/2017. Technical Manual

Transcription

1 ARMATA To prevent punhing failure of onrete slabs Version: AE, SA 08/2017 Tehnial Manual

2 ARMATA To prevent punhing failure of onrete slabs Allows for a slim fl oor Eliminates olumn apitals and drop panels above olumns Quik and easy installation Flexibility in design and delivery Improves the dutility of slabs Improves bonding onditions in onrete elements thanks to ribs on the studs Design aording to ACI for stati and seismi loading using Peikko Designer Peikko s ARMATA is primarily used to inrease the punhing shear resistane of ast-in-situ onrete slabs without inreasing the slab s thikness. ARMATA an be used in slab-on-grade foundations and in elevated slabs, suh as reinfored onrete slabs or posttensioned slabs. When used in elevated slabs, ARMATA an eliminate the need for dropdown panels or olumn aps, thus reduing the osts assoiated with formwork for onrete. Compared to traditional reinforement systems, ARMATA has the added benefit of quik installation times, leading to redued labor osts. Moreover, a thinner slab will lead to a lower floor-to-floor height and thereby a redued building height or the possibility to have an extra floor within the same building footprint. Besides inreasing the resistane of the slab, ARMATA punhing reinforement also inreases its dutility. ARMATA Rail ARMATA is produed from deformed reinforement bars. The exellent bonding onditions and mehanial properties of the deformed bars allow for an optimized slab design by reduing the total amount of punhing reinforement. ARMATA rails onsist of double-headed ribbed studs attahed to a steel flat bar. The type, geometry and dimensions of ARMATA rails may be designed and the resistanes of the onrete members reinfored by ARMATA rails may be verified using Peikko Designer in aordane with the requirements of ACI ARMATA Punhing Reinforement

3 Contents About ARMATA 4 1. Produt properties Strutural behavior Limitations for appliation Material properties Resistanes... 7 Selet ARMATA 8 Install ARMATA 15 Revision: 001

4 About ARMATA 1. Produt properties Reinfored onrete slabs are urrently one of the most popular strutural systems used in residential and ommerial buildings, parking garages and many other types of struture. The system usually onsists of slabs that are loally supported by olumns or walls without a beam system (Figure 1). Suh a onfiguration allows for optimal utilization of the floor area and signifiant savings with regards to the total height of the building. Figure 1. Flat slab supported on olumns and walls. Between supports, the slab is usually designed as a two-way slab to resist bending moments in two orthogonal diretions. Near supports, the bending moments are ombined with transverse loads reations from supports. Suh ombined loading results in a state of stress that may lead to failure of the slab alled punhing shear. In most ases, the punhing resistane of the slab is limited by the thikness of the onrete slab. Punhing shear usually ours when a onrete one is separated from the slab, bending reinforement is pulled away from onrete, and the slab falls down due to gravity (Figure 2). Experiene shows that failure by punhing is partiularly dangerous sine it is a brittle phenomenon that ours suddenly without forewarning signs (extensive deformations, raks, et.). Moreover, the failure of one olumn may impat the adjaent olumns and lead to a hain reation failure of the entire reinfored onrete floor. Figure 2. Failure of a slab by punhing. A slab without vertial reinforement has a very limited resistane against punhing failure. This resistane may be inreased by plaing ARMATA rails in the onrete slab in suh a manner that it prevents the onrete one to develop (Figure 3). Besides inreasing the resistane of the slab, ARMATA rails also inrease its dutility. ARMATA rails are also used in foundation slabs in a similar manner as in floor slabs. Other appliations are also possible: ARMATA rails an be used as shear reinforement in beams and in walls. Figure 3. Flat slab reinfored with ARMATA rails. 4 ARMATA

5 About ARMATA ARMATA rails onsist of double-headed ribbed steel studs welded to a steel flat bar (Figure 4a). The flat bar has no load-bearing funtion; it only guarantees the orret spaing and positioning of the studs during their installation in onrete as presribed by ASTM-A1044 (2016a). Figure 4a. Example of an ARMATA rail. Figure 4b. Height and over of ARMATA studs within the slab. C H C H: height C: over top and bottom The height of the ARMATA studs depends on the thikness of the slab and onrete over of the flexural reinforement of the slab (Figure 4b). The head of the studs is onsidered to be fully anhored into the onrete so that the maximum tensile resistanes of ARMATA studs an be developed. ARMATA studs are available in diameters 10mm (3 8 ), 12mm (1 2 ), 16mm (5 8 ), 20mm (3 4 ) and an be identified by the marking PEIKKO # or PG # and the fatory number (Figure 4). ARMATA studs are produed in height inrements of 10mm. Studs with 5mm inrements will be rounded down to the nearest 5mm inrement based on Setion of ACI and Chapter 6 of ACI 421.1R-10. For example: 227mm long studs will be rounded down to 225mm. Figure 4. Marking of ARMATA studs. D - Diameter of the head H - Height of the studs d - Diameter of the shank ross-setional area of double headed stud Marking at the ends of the studs: PG PEIKKO # # Version: AE, SA 08/2017 5

6 About ARMATA 1.1 Strutural behavior The stati model of a loally supported slab without punhing reinforement is shown in Figures 5 and 6. The external loads of the slab are balaned by a system of onrete struts and ties. The punhing resistane of the slab is limited by the tensile strength of the ties. Figure 5. Fores in the slab without ARMATA before failure. Figure 6. Fores in the slab without ARMATA at failure. V Bending raks V Punhing rak H H Tension Compression V Tension Compression V Reinforing the slab with ARMATA involves replaing the onrete ties with vertial steel reinforement elements (Figure 7). The tensile fore is developed in the shank of the ARMATA studs and anhored into onrete at both ends of the studs by the heads. The diameter and number of steel elements to be plaed in the slab has to be determined so that: ARMATA studs adjaent to the loaded area/olumn have suffiient resistane to prevent the development of a punhing one ARMATA punhing reinforement assembly spreads the load further away from the support Figure 7. V Fores in a slab with ARMATA studs. Tension Compression H Un-reinfored area Reinfored area Compressive stress in onrete V 1.2 Limitations for appliation The ARMATA studs at as vertial tensile omponents within the system of internal fores in the slab. They have a limited influene on the resistane of the ompressive omponent of this system (onrete struts). The design and detailing of both ARMATA rails and the slab reinfored by ARMATA rails is performed on a ase-by-ase basis for eah projet and approved by the Engineer of Reord. A omprehensive set of rules for the verifiation of the resistane of slabs reinfored by rail elements under stati and seismi loads is provided by ACI ARMATA

7 About ARMATA 1.3 Material properties ARMATA studs are fabriated in aordane with ASTM-A1044 (2016a). The strength and dutility requirements are: Tensile strength, min Yield strength, min 550 MPa 420 MPa 2. Resistanes The resistane of a onrete member reinfored by ARMATA rails must be verified ase-by-ase for eah projet. Peikko s design software (Peikko Designer ) is available online and an be used to design the ARMATA rail type and size, and to verify the resistanes of the onrete members reinfored by the ARMATA rails in aordane with ACI Version: AE, SA 08/2017 7

8 Selet ARMATA Selet ARMATA An example of the proedure used for the design and seletion of ARMATA in aordane with ACI reated and implemented in Peikko Designer is presented below. Column dimension a = 350 mm b = 350 mm Conrete strength f = 37 MPa Conrete density Normal Slab thikness h = 320 mm Conrete over bottom b = 25 mm Conrete over top t = 25 mm Diameter of bending d bx = No. 4 reinforement d by = No. 4 Applied load V u = 2000 kn Bending moments M uox = 30 knm M uoy = 35 knm Position of olumn Internal olumn h C t C b d by Bending reinforement d bx d x d y 1. Effetive depth of slab» Effetive depth d y h 0 d by / mm dx h 0 dby d bx / mm dx dy d mm ASTM Standard reinforing bars Bar size, no. Nominal diameter, in. Nominal diameter, mm Critial setion (b 0 ) and Area of ritial setion (A ) (ACI ) 0 b0 2 a d b d 2530 mm A b d mm² 3. Geometrial harateristis of ritial setion» Centroid of ritial setion x y 0 0 l x,i l l y,i l r x,i y,i i r i 0 mm 0 mm 0.5d b 0.5d x l x 0.5d a 0.5d y Column b 0 l y» Neutral axis properties Moment of inertia J x d lx,i r i² mm J y d ly,i r i² mm J 4 0in. xy » Prinipal axis properties Moment of inertia J mm J mm» Rotation of prinipal axis ARMATA

9 Selet ARMATA 4. Design value of punhing shear stresses (ACI )» Moment oeffiients 1 1 v,x v,y l2 2 l l 3 l 1 2» Moments with eentriity M M os M sin 35 knm u1 ux uy M M sin M os 30 knm u2 ux uy» Shear stress at ritial setion Vu 10 v1m u110 yi v2 M u2 10 xi vu,i MPa A J J Resistane of slab without punhing reinforement at ritial setion (ACI )» Nominal shear strength for the two-way members without shear reinforement vn v f' f' v min MPa 12 f' s d 2 b0 12» Maximum shear strength for the two-way members f' MPa 3 6. Load bearing apaity of the slab f' vn vu [MPa] ARMATA punhing reinforement an be used. No ARMATA punhing reinforement is needed if: v v n u ARMATA punhing reinforement an be used if: v v 2 n u f' 3 Maximum resistane of slab exeeded if: v 2 u f' 3 Version: AE, SA 08/2017 9

10 Selet ARMATA 7. Dimension of stud (ACI )» Height of studs ARMATA studs are produed in height inrements of 10 mm. Studs with 5mm inrements will be rounded down to the nearest 5mm inrement based on Setion of ACI and Chapter 6 of ACI 421.1R-10. For example: 227 mm long studs will be rounded down to 225 mm. Support s 0 s h hd b t 270 mm» Spaing between elements s0 s 140 mm 140 mm» Chek spaing Conditions: s 140 mm s / d Corret 0 0 s d s 140 mm s / d Corret f' IF : vu s 0.75d 2 f' IF : vu s 0.5d 2 (ACI Table ) 8. Outer ritial setion b1 (ACI )» Nominal shear strength for the two-way members at the outer ritial setion v v n,out f' v,out 2 12 b1 Length of outer ritial setion f' 2 v u,out( b 1 ) iteration A,out Area of outer ritial setion 12 1 Dimension from olumn to outer ritial setion b mm A mm²,out 10 ARMATA

11 Selet ARMATA 9. Geometrial harateristis of outer ritial setion» Centroid of ritial setion lx,i ri x0 0 mm l x,i b 1 y 0 l y,i l r y,i i 0 mm x b 0 y a b =d/2 1» Neutral axis properties Moment of inertia J d l r mm J d l r mm J x,prov x,i i y,prov y,i i 4 xy,prov 0 mm» Prinipal axis properties Moment of inertia J1,prov mm J mm 2,prov» Rotation of prinipal axis Design value of punhing shear stresses at outer ritial setion» Shear stress at ritial setion v u,out M 10 y M 10 x Vu 10 v1 u1,prov out v2 u2,prov out A J J,out 1,prov 2,prov MPa 11. Resistane of slab with punhing reinforement at outer ritial setion v u v n v v v 2 n,out,out f' vu,out [ MPa ] f' Number of ARMATA studs between olumn and outer perimeter 1 0 nreq d s s Version: AE, SA 08/

12 Selet ARMATA 13. Number of ARMATA Rails around olumn 1. Strength ondition m,req g y v v v u s v f' 4 m req vs b0 s f A yt A 2. Spaing ondition - m spa Spaing must fulfill onditions a. ACI gx 2d g 2d y Total number of Rails around olumn m req m max 8 m spa A A - The ross setion area of one stud s - Spaing between adjaent studs b 0 - Length of ritial ontrol perimeter f yt - Speified yield strength of the ARMATA Stud a b g x 14. Resistane of slab with ARMATA at ritial setion v s,prov Av f b s 0 yt f' v,prov MPa 12 n,prov,prov s,prov 2.67 MPa v v v MPa A v the ross-setional area of the shear reinforement on one peripheral line parallel to the perimeter of the olumn setion. v n,prov v u [ MPa ] 15. Result» Complete ARMATA Rails 8x ARMATA » Combined ARMATA Rails 8x ARMATA & 8x ARMATA ARMATA

13 Selet ARMATA The resulting type and layout of the reinforement proposed by Peikko Designer is the most eonomial design. If needed, the diameter of studs and the number of ARMATA rails an be manually modified by the user. The designed ARMATA punhing reinforement assembly will be defined by a unique Peikko item ode. The plan and setion drawings of the seleted ARMATA reinforement an also be printed by Peikko Designer or exported as DWG files and shedule. The printed output of Peikko Designer also inludes a summary of input data and stati verifiations of resistanes for eah individual ase within eah projet. The list of reommended aessories for the installation of ARMATA is also available in the printed output of Peikko Designer. The ARMATA rail may be provided either as a omplete element (with all ARMATA studs welded to one steel shape) or may be assembled onsite from two or more shorter symmetrial ARMATA rails (Figure 8). Version: AE, SA 08/

14 Selet ARMATA Figure 8. Complete ARMATA rail and equivalent solution with a ombination of shorter ARMATA rails. Peikko : 8x ARMATA Peikko : 8x ARMATA & 8x ARMATA The typial proedure for seleting the appropriate type of ARMATA using Peikko Designer is summarized in the diagram in Figure 9. Figure 9. Proedure to selet ARMATA. Materials Geometry Fores Type of ARMATA User input Design of ARMATA Resistane of slab Height of studs Number of studs Diameter of studs Spaing of studs Slab without ARMATA Max. resistane of slab (rushing of onrete) Slab with ARMATA Slab outside of the area reinfored by ARMATA Automati proedure by Peikko Designer 8xARMATA Number of ARMATA Rails around the olumn Type of stud Diameter of ARMATA Stud Height of the ARMATA Stud Spaing of studs within the ARMATA Rail element between stud Spaing of studs within the ARMATA Rail element between the olumn and first stud Number of ARMATA Studs within one rail Note 1: ARMATA prodution marking remains in imperial system. Note 2: Diameter of studs are listed in table of worked example on page 8, further information an be found in ACI APPENDIX A Steel reinforement information. 14 ARMATA

15 Install ARMATA Install ARMATA ARMATA rails are installed in the slab aording to the design plans. Eah ARMATA rail is identified with label loated at the end of the rail. The label is determined by the number of rail onfigurations for eah olumn for a speifi projet. Example: Item ID Paking Date XARMATA Bottom installation: ARMATA rails are plaed below the main reinforement of the slab prior to the installation of the bending reinforement. In order to ahieve a suffiient onrete over of the headed studs, plasti spaers are mounted onto the ARMATA rails. Spaers are delivered with rails Version: AE, SA 08/

16 Install ARMATA Top installation: The ARMATA rails are plaed on top of the main reinforement of the slab. All bending reinforement is installed prior to the ARMATA rails ARMATA

17 Notes Version: AE, SA 08/

18 Notes 18 ARMATA

19 Notes Version: AE, SA 08/

20 PEIKKO GROUP CORPORATION Peikko Group Corporation is a leading global supplier of onrete onnetions and omposite strutures. Peikko s innovative solutions make the ustomers building proess faster, easier and more reliable. Peikko has subsidiaries in over 30 ountries in Asia-Paifi, Europe, the Middle East, and North Ameria, with manufaturing operations in 9 ountries. Our aim is to serve our ustomers loally with leading solutions in the field in terms of quality, safety, and innovation. Peikko is a family-owned and run ompany with over 1200 professionals. Peikko was founded in 1965 and is headquartered in Lahti, Finland. Peikko Group - Conrete Connetions sine 1965