Technical Lecture CRET Series 100 Design Stefan Lips

Transcription

1 Mehr Leistung. Mehr Wert. Technical Lecture CRET Series 100 Design Stefan Lips

2 Contents Scope of application Component structure Design concept 2

3 Scope of application The main area of application is shear load transmission in movement joints. Movement joints allow the deflection of adjacent building elements resulting from Shrinkage Example with joint spacing 20 m: Δf mm = 10 mm Changes in temperature Example with joint spacing 20 m and temperature change 20 C: Δf mm 20 C C = 4 mm Other deflection factors: creep, differential subsidence, etc. The dowels can be statically and dynamically (cyclic / fatigue) loaded 3

4 Scope of application 4

5 Scope of application Shear load transmission in joints can become necessary For reasons of equilibrium To ensure deflection compatibility between joint edges Benefits of using shear load connectors: Simple joint geometry Simple shuttering Simple reinforcement layout Space saving by eliminating double columns or double walls Cost and space savings through phased building of structures (with optional scheduling between completion of phases) 5

6 Scope of application Considering slab displacement Considering centre of displacement Fixed Type 1 Type 2 6

7 Component structure CRET Series 100 normal Sliding sleeve Load distribution frame Dowel Nailing plate 7

8 Component structure CRET Series 100V with lateral displacement Sliding sleeve Load distribution frame Dowel Nailing plate 8

9 Component structure Required corrosion resistance class KWK (based on DIBt Approval Z30.3-6; SIA 2029; SIA 262) KWK Criteria Examples I II Dry, rarely damp, often damp: distance from sea > 10 km; distance to roads with de-icing salt > 0.1 km Permanent dampness; industrial areas; distance from sea > 1 km; distance to roads with de-icing salt > 0.01 km General building elements General building elements 9 III IV Distance from sea < 1 km; distance to roads with de-icing salt < 0.01 km Other Building elements close to spray range of road traffic areas; building elements close to the sea Elements of bridges, parking levels, walkways treated with salt, retaining walls exposed to spray containing chlorine For uninspected building elements, it is advisable to select a higher corrosion resistance class.

10 Component structure Component Material number Corrosion resistance class Dowel (duplex steel) Load distribution frame (austenitic steel) or (duplex steel) IV III Material numbers and corrosion resistance classes to SIA Data Sheet 2029 and DIBt Approval Z

11 Design basis EN :2004, Eurocode 2: Concrete structures EN , -1-8:2005, Eurocode 3: Steel structures EN :2004, Eurocode 4: Composite structures National Appendices to EC2, EC3 und EC4 DIBt Approval Z

12 Failure modes Dowel Load distribution frame Concrete pressure on the dowel Concrete compressive diagonals at the slab edge Suspension reinforcement Shear resistance of the slab 12

13 Dowel Limited by M-V interaction in the dowel (EC 3, 6.2.8) d V pl,rd M V,Rd = (1-r) M pl,rd r = (2V d /V pl,rd -1) 2 V d M pl,rd V d V d M d V d e/2 M d,max M pl,rd = f yd d 3 /6 e/2 13

14 Load distribution frame T Rd d Limited by sheet metal: - Hole bearing pressure - Tensile resistance V d 14

15 Concrete pressure q cd = f cd,sup d d Limited by concrete resistance at the connectors (EC 4, ): f cd,sup = a 0 (f ck E cm ) 0.5 /g v V d 15

16 Concrete compression diagonals & stirrup reinforcement Compressive forces in concrete Tensile forces in the reinforcement V 16

17 Slab shear resistance Slab shear resistance: v Rd > F d /a D -> Minimum distance between dowels 17

18 Design relevant parameters Action (load) Joint gap Slab thickness Concrete quality Distance between dowels 18

19 e = f + Δf Installation condition f Δf Post-deflection (Design condition) Δf 19

20 Required slab edge reinforcement 20

21 The design concept was validated on the basis of 103 tests (with over 200 connectors) École polytechnique fédérale de Lausanne EPFL Essais de rupture sur des bandes de dalles; liées par des goujons CRET série 100-1; EPFL - MCS d & MCS d University of Stuttgart Test Report AS 155/01 04/20 dt Test Report AS 155/02 04/21 dt Test Report AS 155/03 05/20 dt

22 Test results EPF Lausanne (-> high deflection capacity) 22

23 Test results EPF Lausanne 23

24 Load table (documentation) Dorn Typ Plattenhöhe Beton Fugenöffnung e [mm] a D,min [m] Anzahl erforderlicher Bügel n erf [-] h [mm] fck [N/mm2] r =0.2% r =0.5% r =1.0% d s = 8 mm d s = 10 mm d s = 12 mm d s = 16 mm d s =20 mm 122 N N N N N N N N N N N N N N

25 Load table (software) Stirrups to be optimised using the software Dorn Typ Plattenhöhe Beton Fugenöffnung e [mm] Plattenwiderstand v Rd [kn/m] r r r =0.2% =0.5% =1.0% Bügelwiderstand Z Rd,s [kn] je Bügel Wirksamkeit 'beta' [-] je Bügel fck d s = 8 d s = 10 d s = 12 d s = 16 d s = h [mm] [N/mm2] mm mm mm mm mm Bügel Bügel Bügel Bügel 122 N N N N N N N N N N N N N N

26 Application with beams -> Defining anchor reinforcement via stress fields 26

27 Summary The key design parameters are: Action Joint gap Slab thickness Concrete quality Distance between dowels The design of CRET dowels includes all necessary verifications Load distribution frame Concrete pressure at the dowel Concrete compressive diagonals on slab edge Suspension reinforcement Slab shear resistance It has been established that with some competing products, not all parameters or verifications have been taken into consideration. Hence, some competing products state ultimate load figures that simply cannot be transmitted. In such cases, civil engineers have to conduct the remaining verifications themselves in order to determine the true ultimate load figures. 27