Material properties Felt and Reinforcement For Shear test of Reinforced Concrete Slab

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1 Delft University of Technology Report nr Faculty of Civil Engineering and Geosciences Department of Design & Construction Concrete Structures September 15, 211 Material properties Felt and Reinforcement For Shear test of Reinforced Concrete Slab Author: Bc. Zdenka Prochazkova Ir. Eva Lantsoght Delft University of Technology Report nr

2 Stevin Report nr

3 Faculty of Civil Engineering and Geosciences Department of Design & Construction Concrete Structures September 15, 211 Material properties Felt and Reinforcement For Shear test of Reinforced Concrete Slab Author: Bc. Zdenka Prochazkova Ir. Eva Lantsoght 211 Delft University of Technology Faculty of Civil Engineering and Geosciences Department of Design & Construction Concrete Structures Stevinlaboratorium Postbus GA Delft Telephone /4578 Telefax /7438 AUTEURSRECHTEN Alle rechten voorbehouden. Niets uit deze uitgave mag worden verveelvoudigd, opgeslagen in een geautomatiseerd gegevensbestand, of openbaar gemaakt, in enige vorm of op enige wijze, hetzij elektronisch, mechanisch, door fotokopieën, opnamen of enig andere manier zonder voorafgaande schriftelijke toestemming van de universiteit. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system of any nature, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the university. AANSPRAKELIJKHEID De TU Delft en degenen die aan deze publicatie hebben meegewerkt, hebben een zo groot mogelijke zorgvuldigheid betracht bij het samenstellen van deze uitgave. Nochtans moet de mogelijkheid niet worden uitgesloten dat er toch fouten en onvolledigheden in deze uitgave voorkomen. Ieder gebruik van deze uitgave en gegevens daaruit is geheel voor eigen risico van de gebruiker en de TU Delft sluit, mede ten behoeve van al degenen die aan deze uitgave hebben meegewerkt, iedere aansprakelijkheid uit voor schade die mocht voortvloeien uit het gebruik van deze uitgave en de daarin opgenomen gegevens, hetzij de schade die mocht voortvloeien uit opzet of grove schuld zijdens de TU Delft en/of degenen die aan deze uitgave hebben meegewerkt. 1

4 Contents 1. Felt and plywood Test setup Test I Test II Test III Results Stress strain diagrams Specimen 1: Plywood Specimen 4: Plywood/felt 5mm P Specimen 7 9: Plywood/felt 1mm N Specimen 12: Plywood/felt 15mm N Specimen 135: Felt 5mm P Specimen 168: Felt 1mm N Specimen 191: Felt 15mm N Specimen 224: Plywood/felt 5mm N Specimen 257: Felt 5mm N Specimen 281: Plywood/2x5mm felt P5 I Specimen 325: Plywood/2x5mm felt P5 II Specimen 36: Plywood/2x5mm felt P5 III Reinforcement Test I Test II Test III Stress strain diagram: Diameter Stress strain diagram: Diameter Stress strain diagram: Diameter Appendices Appendix A Appendix B Appendix C References

5 1. Felt and plywood A compression test was carried out on plywood, felt and on the combination of plywood and felt. Three thicknesses (5 mm, 1 mm and 15 mm) and two types (P5 and N1) of felt were tested. The plywood had a thickness of 8mm. In total 36 specimens were tested. The list of specimens, tested materials and type of tests are shown in Table 1. Three types of tests were carried out only dynamic loading (Test I.), 24 hours constant load (Test II.) and 7 days constant load (Test III.)(see Sections 1.2, 1.3 and 1.4). Table 1: List of specimens Specimen Tested materials Type of test 1 Plywood Test I. 4 Plywood/felt 5mm P5 Test I. 7 9 Plywood/felt 1mm N1 Test I. 12 Plywood/felt 15mm N1 Test I. 135 Felt 5mm P5 Test I. 168 Felt 1mm N1 Test I. 191 Felt 15mm N1 Test I. 224 Plywood/felt 5mm N1 Test I. 257 Felt 5mm N1 Test I. 281 Plywood/ 2x5mm felt P5 Test I. 325 Plywood/ 2x5mm felt P5 Test II. 36 Plywood/ 2x5mm felt P5 Test III. 3

6 1.1. Test setup The specimens were 1x1 mm 2 and loaded up to 8kN (maximum stress 8 MPa). The deformation was measured with 4 LVDT s with a stroke of 1 mm. See Figure 1 for the testt setup and Figure 2 for the specimen, load plates and LVDT s. Figure 1: Felt and plywood test setup Figure 2: Felt and plywood test setup 4

7 1.2. Test I. Test I. was used to test Specimens 11. The test started as manually displacement controlled. At a small force, about 2 kn, the displacement control switched to force controlled. A ramp was applied with a speed of 2 kn/sec to 8 kn. After this a second ramp with the same speed lowered the force to 2 kn. This was repeated three times. After this sequence the control was switched back to manual displacement control and the specimen was unloaded. As an example of the experiments results the stress strain diagram of specimens 281 is presented (see Figure 3). Plywood/2x5mm felt P5 Test I test 28 test 3 test 31 Figure 3: Stress strain diagram of plywood and felt P5 combination Test I Test II. First it was assumed that the load from the self weight of the slab was too small to influence the felt properties. The results from Test I. were used in several FEM models but the behavior of the structure in the FEM analysis was not satisfactory. Especially in the beginning of the loading, the FEM analysis showed a very soft response. Therefore, Test II. was carried out and a large difference in the initial stiffness of the felt was found (see Figure 6 ). In the second test the specimen was first manually loaded to a force of 2 kn. This load was kept for 24 hours and then cyclic loading was applied like in Test I. The load of 2 kn is corresponding to the load subjected on the felt by the self weight of the slab. Specimens 325 were tested according to this procedure(see Figure 4 and Figure 5). 5

8 Plywood/2x5mm felt P5 Test II test 32 test 33 test 35 Figure 4: Stress strain diagram of plywood and felt P5 combination Test II. Plywood/2x5mm felt P5 Test II test 32 test 33 test 35 Figure 5: Stress strain diagram of plywood and felt P5 combination Test II. cyclic loading only: a creep part of the stress strain diagram of each specimen from the Figure 4 was taken out 6

9 Plywood/2x5mm felt P Test I. Test II. Figure 6: Comparison of Test I. and Test II Test III. Test III. was the same as Test II. The only difference was that the constant load of 2kN was kept for one week. The stress strain diagram of this specimen was almost identical to the results from Test II. (see Figure 7). Therefore no more specimens were tested and Test II. was considered as sufficient for the determination of the actual felt properties. Plywood/2x5mm felt P Test I. Test II. Test III. Figure 7: Comparison of Test I.,Test II. and Test III. 7

10 1.5. Results Stress strain diagrams Specimen 1: Plywood Plywood test 1 test 2 test Specimen 4: Plywood/felt 5mm P5 Plywood felt 5mm P test 4 test 5 test 6 8

11 Specimen 7 9: Plywood/felt 1mm N1 Plywood / felt 1 mm N test 7 test 8 test Specimen 12: Plywood/felt 15mm N1 Plywood/ felt 15 mm N test 1 test 11 test 12 9

12 Specimen 135: Felt 5mm P5 Felt 5 mm P test 13 test 14 test Specimen 168: Felt 1mm N1 Felt 1 mm N test 16 test 17 test

13 Specimen 191: Felt 15mm N1 Felt 15mm N test 19 test 2 test Specimen 224: Plywood/felt 5mm N1 Plywood felt 5mm N test 22 test 23 test 24 11

14 Specimen 257: Felt 5mm N1 Felt 5mm N test 25 test 26 test Specimen 281: Plywood/2x5mm felt P5 I. Plywood/2x5mm felt P5 Test I test 28 test 3 test 31 12

15 Specimen 325: Plywood/2x5mm felt P5 II. Plywood/2x5mm felt P5 Test II test 32 test 33 test Specimen 36: Plywood/2x5mm felt P5 III. Plywood/2x5mm felt P5 Test III test 36 13

16 2. Reinforcement Three types of tensile tests were executed on the reinforcement. Test I. was carried out at the Structural Design Lab, CiTG TU Delft, but because this laboratory does not have equipment for a proper tensile test of structural reinforcement (larger diameters) according to the code provisions, the test did not show good results. Test II. was still carried out at the Structural Design Lab, CiTG TU Delft. This test was not according to the code provisions but it helped to prove that Test I. underestimated the actual properties of the reinforcement. Therefore the reinforcement was sent to the company Exova B.V., which could provide a code based proper tensile test of the reinforcement Test III Test I. The first tensile test was carried at the Structural Design Lab, CiTG TU Delft. The Steel laboratory has equipment for the tensile test of a dog bone steel sample. Four types of reinforcement and three specimens of each type were tested (see Table 2). The reinforcement was not trimmed to maintain the cross sectional area. Almost all specimens failed near to the clamped ends and the extensometers were too small for a diameter 2 bar. The stress strain diagrams of diameters 1 mm and 2 mm ribbed can be seen in Figure 8 and Figure 9. The stress strain diagram of ribbed reinforcement of diameter 1 looked correct. A stiffness of about 2GPa and the yield stress could be found with.2 % strain offset (as an example diameter 1 ribbed see Figure 8). The stress strain diagram of diameter 2 did not look very good (as an example diameter 2 ribbed see Figure 9). The stiffness was lower than the required stiffness of the 2GPa and yield stress (43 MPa) was also lower than required (5 MPa). Table 2: List of specimens Test I. Specimen Diameter [mm] Type ZA_1 D1 plain ZB_1 D1 plain ZC_1 D1 plain ZD_1 D1 ribbed ZE_1 D1 ribbed ZF_1 D1 ribbed ZK_1 D2 plain ZL_1 D2 plain ZM_1 D2 plain ZP_1 D2 ribbed ZR_1 D2 ribbed ZS_1 D2 ribbed 14

17 Reinforcement D1 ribbed D 25 E 2 F 15,2% Figure 8: Stress strain diagram of reinforcement diameter Reinforcement D2 ribbed P R S,2% 2 GPA Figure 9: Stress strain diagram of reinforcement diameter

18 2.2. Test II. Test II. was still executed in the Steel Laboratory of Citg TU Delft. Only three specimens of ribbed reinforcement diameter 2 were tested. Only in the middle of the specimens length the reinforcement ribs were trimmed (the cross sectional area was maintained). The strain gauges, which helped to indicate the yield strength, were placed on that trimmed area in the middle of the initial distance of the clamps. The change of the position of the actuators was used to obtain the rest of the stress strain diagram. Although Test II. was not a code based type of tensile test for the reinforcement, it indicated that Test I. was not correct. Therefore, the reinforcement was sent to a specialized laboratory D2 ribbed S2 S3 S4 Strain gauges S2 Strain gauges S3 Strain gauges S4 2 GPa Figure 1: Stress strain diagram of reinforcement diameter 2 16

19 2.3. Test III. Test III. was carried out by the company Exova B.V. The plain reinforcement bars were tested according EN ISO 6892 and the ribbed reinforcement was tested according NEN 68. All specimens were tested with an exception that the length of the extensometer was 25 mm. The original gauge length according EN ISO 6892 and NEN 68 should be Lo k So Where k is a coefficient of proportionality (the internationally adopted value for k is 5.65) and S o is the original cross sectional area. Three specimens of each diameter 1 mm, 16 mm and 2 mm, plain and ribbed were tested (see Table 3). Table 3: List of specimens Test III. Sample Diameter [mm] Type 1 D1 ribbed 2 D1 ribbed 3 D1 ribbed 4 D16 ribbed 5 D16 ribbed 6 D16 ribbed 7 D2 ribbed 8 D2 ribbed 9 D2 ribbed 1 D1 plain 11 D1 plain 12 D1 plain 13 D2 plain 14 D2 plain 15 D2 plain Table 4: Summary of the reinforcement properties Diameter [mm] Type f y [MPa] f u [MPa] D1 ribbed D16 ribbed D2 ribbed D1 plain D2 plain

20 Stress strain diagram: Diameter Reinforcement D1 ribbed Sample 1 Sample 2 Sample 3 yield stress,2% 7 Reinforcement D1 plain Sample 1 Sample 11 Sample 12 yield stress,2% 18

21 Stress strain diagram: Diameter 16 Reinforcement D16 ribbed Sample 4 2 Sample 5 15 Sample 6 1 yield stress,2%

22 Stress strain diagram: Diameter 2 Reinforcement D2 - ribbed Sample 7 Sample 8 Sample 9 yield stress,2% 65 Reinforcement D2 ribbed Sample 13 Sample 14 Sample 15 yield stress,2%

23 3. Appendices 3.1. Appendix A The material properties of felt type P5 given by the producer. 21

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25 3.2. Appendix B The material properties of felt type N1 given by the producer. 23

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27 3.3. Appendix C Test results of the tensile test of the reinforcement from Exova B.V. 25

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29 4. References NEN EN ISO 6892:29, Metallic materials Tensile testing Part 1: Method of test at room temperature, September 29 27