Shear Tests of Reinforced Concrete Slabs: Experimental Data of Undamaged Slabs. Concept v. 26-10-2012

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Department of Design & Construction – Concrete Structures

October 26, 2012

Shear tests of Reinforced Concrete Slabs

Experimental data of Undamaged Slabs

CONCEPT v. 26-10-2012

Author:

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Shear tests of Reinforced Concrete Slabs

Experimental data of Undamaged Slabs

CONCEPT v. 26-10-2012

Author:

Ir. E. Lantsoght

Delft University of Technology

Faculty of Civil Engineering and Geosciences

Department of Design & Construction – Concrete Structures Stevinlaboratorium Postbus 5048 2600 GA Delft Telephone 015 2783990/4578 Telefax 015 2785895/7438 AUTEURSRECHTEN

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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

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1. Introduction ... 5 2. Material properties ... 8 2.1. Concrete mix ... 8 2.1.1. Cast 1: S1, S2 ... 8 2.1.2. Cast 2: S3, S4 ... 12 2.1.3. Cast 3: S5, S6 ... 16 2.1.4. Cast 4: S7, S8, BS1, BM1, BL1 ... 20 2.1.5. Cast 5: S9, S10, BS2, BM2, BL2 ... 25 2.1.6. Cast 6: BS3, BM3, BL3 ... 28 2.1.7. Cast 7: S11, S12 ... 32 2.1.8. Cast 8: S13, S14 ... 36 2.1.9. Cast 9: BX3, BX1 ... 39 2.1.10. Cast 10: BX2 ... 42 2.1.11. Cast 11: S15, S16 ... 46 2.1.12. Cast 12: S17, S18 ... 49 2.2. Steel ... 53 3. Specimens ... 55

4. Loading scheme and measuring devices ... 61

5. Presentation of the results ... 73

5.1. Introduction ... 73 5.2. Results of slabs ... 74 5.2.1. S1 ... 74 5.2.2. S2 ... 84 5.2.3. S3 ... 94 5.2.4. S4 ... 105 5.2.5. S5 ... 116 5.2.6. S6 ... 127 5.2.7. S7 ... 148 5.2.8. S8 ... 168 5.2.9. S9 ... 180 5.2.10. S10 ... 192 5.2.11. S11 ... 213 5.2.12. S12 ... 224 5.2.13. S13 ... 245 5.2.14. S14 ... 256 5.2.15. S15 ... 278 5.2.16. S16 ... 292 5.2.17. S17 ... 319 5.2.18. S18 ... 333 5.3. Results of beams ... 361 5.3.1. BS1 ... 361 5.3.2. BS2 ... 371 5.3.3. BS3 ... 383 5.3.4. BM1 ... 395 5.3.5. BM2 ... 406 5.3.6. BM3 ... 419 5.3.7. BL1 ... 431 5.3.8. BL2 ... 443

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5.3.10. BX1 ... 471

5.3.11. BX2 ... 485

5.3.12. BX3 ... 499

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1. Introduction

Shear in reinforced concrete members has been studied over many decades. Most research either focuses on one-way shear in beams or on two-way shear

(punching shear) in slabs. The one-way shear capacity of a slab is typically calculated using the beam formulas in which the width b is replaced by the effective width beff.

The effective width is calculated by using a 45° practical rule (Fig. 1.1). If the shear span becomes smaller for slabs, then the effective width becomes smaller and thus the ultimate shear capacity becomes smaller.

Fig. 1.1.: Load spreading in plan view.

A limited amount of test data is available concerning the shear capacity of slabs under concentrated loads near to supports. The most comprehensive test series has been carried out by Regan (1982). The size of the tested slab specimens was 1,6m x 1,2m x 0,1m (Fig. 1.2). Tests were carried out for different values of the shear span, different load dimensions and at a simple and continuous support (Fig. 1.3). Because of the size effect for shear in concrete slabs, the ultimate shear capacities for large-scale slabs could be lower than expected from Regan’s test results. Regan concluded from his test series that the shear capacity increases with a decrease in shear span and that the shear capacity at a continuous support is higher than at a simple support. As compared to the NEN 6720 much higher effective widths were found from these test results. A limited amount of test data concerning shear in slabs can also be found in Furuuchi, Takahashi, Ueda and Kakuta (1998) and Graff (1933).

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Fig. 1.2: Details of slab arrangement, Regan (1982).

Fig. 1.3: Details of testing arrangement, Regan (1982).

The scope of the research is to study shear in reinforced concrete slabs under concentrated loads close to the supports. A method to calculate the effective width is needed. Testing is carried out to study the influence of the following parameters:

- amount of transverse reinforcement, - size of the load,

- support layout (line support or bearings),

- type of reinforcement (plain bars or deformed bars), - shear span,

- location of load along the width of the slab,

- type of support (simple or continuous support), and - concrete compressive strength.

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This program should provide the information to verify the method described by Regan (1982) and to evaluate existing slab bridges. In this report the experimental results of tests on slabs not previously loaded will be presented.

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2. Material properties

2.1. Concrete mix

2.1.1. Cast 1: S1, S2

The first cast was executed on 08-10-2009. The mix was composed of blast furnace B cement and gravel aggregates with a particle size between 4mm and 16mm, Table 2.1 and Fig. 2.1.

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Fig. 2.1: Sieve analysis Cast 1.

The mix composition is given in Table 2.2.

Table 2.2: Mix composition of cast 1.

The air content was 1,5%. The slump of the mix was according to class S3. The concrete was delivered by a truck mixer. 10 m3 was ordered of which about 7,5 m3 used for casting the slabs. Each slab was casted in 5 layers. During casting poker vibrators were used to compact the concrete of the slabs and cubes. For standard tests 66 cubes were cast on 08-10-2009 of which 48 were reserved for this research. The compaction time for the 150mm cubes was 30 seconds. After casting the slabs and cubes were covered with plastic sheets. The cubes were demoulded after one day and the slabs after two weeks. 24 cubes were stored in the fog room (99% RH and 20°C) and tested at an age of 4, 7, 14 and 28 days. The other cubes and the slabs were stored in the laboratory (65% RH and 15-20°C). These cubes were tested at an age of 39, 57, 70 and 132 days. S1 was tested at 28, 36, 37, 38, 40 and 45 days. S2 was tested at 56, 60, 64, 67, 69 and 70 days. The results of the standard tests on the cubes are given in Table 2.3, in which fcc is the concrete compressive strength of the cube and fcspl the

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2.3.

Table 2.3: Results of cube test for cast 1.

cube age (days) fcc (MPa) fcspl (MPa)

1 4 15,27 2 4 16,24 3 4 16,41 4 4 5,01 5 4 2,97 6 4 4,06 7 7 23,61 8 7 24,13 9 7 23,24 10 7 3,44 11 7 6,16 12 7 3,93 13 14 28,7 14 14 33,44 15 14 30,81 16 14 3,03 17 14 3,19 18 14 3,04 19 28 37,06 20 28 38,95 21 28 38,52 22 28 3,5 23 28 3,46 24 28 3,65 25 39 32,44 26 39 31,8 27 39 35,8 28 57 32,72 29 57 32,53 30 57 34,22 31 57 2,93 32 57 2,67 33 57 2,67 34 70 41,17 35 70 35,51 36 70 30,7 37 70 2,9 38 70 3,07 39 70 3,02 40 132 39,35 41 132 42,44 42 132 37,04

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Fig. 2.2: Development of concrete compressive strength, cast 1.

Fig. 2.3: Development of splitting tensile strength, cast 1.

0 5 10 15 20 25 30 35 40 0 20 40 60 80 100 120 fc ( M P a) time (days) 0 1 2 3 4 5 6 0 10 20 30 40 50 60 70 sp li tt in g s tr en g th ( M P a) time (days)

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The second cast was executed on 20-11-2009. The mix was composed of blast furnace B cement and gravel aggregates with a particle size between 4mm and 16mm, Table 2.4 and Fig. 2.4.

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Fig. 2.4: Sieve analysis of cast 2.

Table 2.5: Mix composition of Cast 2.

The air content was 1,5% and the slump of the mix was 170mm. The concrete was delivered by a truck mixer. 10 m3 was ordered of which about 7,5 m3 used for casting the slabs. Each slab was casted in 5 layers. During casting poker vibrators were used to compact the concrete of the slabs and cubes. For standard tests 66 cubes were cast on 20-11-2009 of which 48 were reserved for this research. The compaction time for the 150mm cubes was 30 seconds. After casting the slabs and cubes were covered with plastic sheets. The cubes were demoulded after one day and the slabs after more than one week. All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 4, 7, 14, 28, 49, 63, 70, 84 and 98 days. The slabs were stored in the laboratory (65% RH and 15-20°C). S3 was tested at 63, 66, 68, 69 and 70 days. S4 was tested at 76, 77, 80, 81, 82 and 88 days. The results of the standard tests on the cubes are given in Table 2.6, in which fcc is the concrete compressive strength of the

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strength in Fig. 2.6.

Table 2.6: Results of cube tests for cast 2.

1 7 29,04 2 7 25,97 3 7 30,09 4 7 2,95 5 7 2,87 6 7 2,96 7 14 38,14 8 14 37,33 9 14 40,92 10 14 3,27 11 14 3,29 12 14 3,35 13 28 49,84 14 28 42,75 15 28 48,65 16 28 51,64 17 28 47 18 28 50,89 19 28 3,93 20 28 3,8 21 28 3,72 22 28 3,87 23 28 3,88 24 28 3,8 25 49 48,22 26 49 53,69 27 49 51,96 28 63 51,04 29 63 51 30 63 53,98 31 63 4,3 32 63 4,17 33 63 4,2 34 70 48,03 35 70 51,76 36 70 52,68 37 70 4,01 38 70 3,92 39 70 4,11 40 84 49,01 41 84 51,37

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42 84 49,89

43 98 52,98

44 98 54,79

45 98 52,57

0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 80 90 100 st re n g th ( M P a) time (days) 0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 0 10 20 30 40 50 60 70 80 90 100 st re n g th ( M P a) time (days)

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2.1.3. Cast 3: S5, S6

The third cast was executed on 02-02-2010. The mix was composed of blast furnace B cement and gravel aggregates with a particle size between 4mm and 16mm, Table 2.7 and Fig. 2.7 .

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Fig. 2.7: Sieve analysis of Cast 3.

Table 2.8: Mix composition Cast 3.

The air content and the slump of the mix were 1,5% and 140mm respectively. The concrete was delivered by a truck mixer. 10 m3 was ordered of which about 7,5 m3 used for casting the slabs. Each slab was casted in 5 layers. During casting poker vibrators were used to compact the concrete of the slabs and cubes. For standard tests 96 cubes were cast on 02-02-2009 of which 72 were reserved for this research. The compaction time for the 150mm cubes was 30 seconds. After casting the slabs and cubes were covered with plastic sheets. The cubes were demoulded after one day and the slabs after about 1,5 weeks. All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 3, 7, 28, 31, 56, 63, 70, 90, 150, 178 and 365 days. Cubes 58 to 60 were stored in the climate room. The slabs were stored in the laboratory (65% RH and 15-20°C). S5 was tested at 31, 34, 35, 36 and 37 days. S6 was tested at 41, 42, 43, 44 and 56days. The results of the standard tests on the cubes are given in Table 2.9, in which fcc is the concrete compressive strength of the cube

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in Fig. 2.9.

Table 2.9: Results of cube tests of cast 3.

1 3 15,92 2 3 15,44 3 3 16,17 4 3 1,68 5 3 1,77 6 3 1,77 7 7 29,4 8 7 28,11 9 7 28,86 10 7 2,91 11 7 2,6 12 7 2,92 13 28 45,52 14 28 43,29 15 28 46,91 16 28 4,05 17 28 3,74 18 28 3,9 19 31 45,54 20 31 45,1 21 31 47,85 22 31 3,73 23 31 3,58 24 31 3,37 25 56 50,2 26 56 49,58 27 56 50,74 28 56 3,95 29 56 4,07 30 56 3,83 31 63 52,36 32 63 51,82 33 63 48,8 34 70 51,29 35 70 42,51 36 70 47,19 37 70 3,84 38 70 3,97 39 70 3,67 40 90 55,16 41 90 53,51 42 90 52,26 43 90 3,96

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44 90 4,30 45 90 4,01 46 150 56,26 47 150 52,92 48 150 55,58 49 178 61,31 50 178 61,04 51 178 58,99 52 178 3,93 53 178 3,27 54 178 3,55 55 365 57,77 56 365 61,76 57 365 59,59 58 365 4,11 59 365 4,25 60 365 3,83

0 10 20 30 40 50 60 70 0 50 100 150 200 250 300 350 fc ( M P a) time (days)

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2.1.4. Cast 4: S7, S8, BS1, BM1, BL1

The fourth cast was executed on 23-02-2010. The mix was composed of Portland cement, blast furnace B cement, fly ash and gravel aggregates with a particle size between 4mm and 16mm, Table 2.10 and Fig. 2.10.

Table 2.10: Sieve analysis of Cast 4.

0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 0 50 100 150 200 250 300 350 spl it ti n g s tr en g th ( M P a ) time (days)

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Fig. 2.10: Sieve analysis of Cast 4.

The air content was 1,5% and the slump of the mix was 170mm. The concrete was delivered by a truck mixer. 12,75 m3 was ordered of which about 7,5 m3 used for casting the slabs and 4,5 m3for the beams. Each slab was casted in 5 layers. BS1 was casted in 2 layers, BM1 was casted in 3 layers and BL1 was casted in 4 layers. During casting poker vibrators were used to compact the concrete of the slabs and beams and the cubes were compacted on the vibration table. For standard tests 102 cubes were cast on 23-02-2009. The compaction time for the 150mm cubes was 30 seconds. After

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demoulded after one day and the slabs and beams after about one week. All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 3, 7, 14, 28, 47, 56, 84, 91, 181, 189, 365, 456, 548 and 730 days. The slabs and beams were stored in the laboratory (65% RH and 15-20°C). S7 was tested at 83, 84, 85, 86 and 87 days. S8 was tested at 47 and 49 days. BS1 was tested at 54 and 56 days. BM1 was tested at 61 and 62 days. BL1 was tested at 189 and 190 days. The results of the standard tests on the cubes are given in Table 2.12, in which fcc is the concrete

compressive strength of the cube and fcspl the concrete tensile splitting strength of the

cube. The development of the concrete compression strength is given in Fig. 2.37 and of the splitting tensile strength in Fig. 2.38.

1 3 46,01 2 3 52 3 3 48,67 4 3 3,75 5 3 4,38 6 3 3,71 7 7 52,26 8 7 60,27 9 7 63,34 10 7 4,84 11 7 4,96 12 7 4,63 13 14 71,78 14 14 64,46 15 14 69,79 16 14 5,25 17 14 5,23 18 14 4,64 19 28 72,96 20 28 69,72 21 28 41,25 22 28 5,49 23 28 5,58 24 28 4,8 25 47 77,99 26 47 76,12 27 47 76,94 28 47 6,03 29 47 5,98 30 47 6,00

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31 56 78,83 32 56 84,11 33 56 81,43 34 56 6,05 35 56 6,12 36 56 6,15 37 84 85,29 38 84 79,93 39 84 80,93 40 84 6,29 41 84 6,18 42 84 6,07 43 91 82,43 44 91 76,66 45 91 72,84 46 91 5,59 47 91 6,13 48 91 6,09 49 181 77,77 50 181 84,89 51 181 79,53 52 181 6,01 53 181 5,98 54 181 6,32 55 189 74,88 56 189 80,22 57 189 74,95 58 365 85,96 59 365 83,64 60 365 72,38 61 365 5,14 62 365 6,22 63 365 5,51 64 456 89,29 65 456 80,71 66 456 79,12 68 548 88,30 69 548 88,30 70 548 6,65 71 548 5,99 72 548 5,91 73 640 81,56 74 640 63,11 75 640 82,77 76 730 86,00 77 730 63,86 78 730 90,72

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80 730 6,22

81 730 6,11

Fig. 2.12: Development of splitting tensile strength, cast 4. -5 5 15 25 35 45 55 65 75 85 95 0 100 200 300 400 500 600 700 fc ( M P a) time (days) 0 1 2 3 4 5 6 7 0 100 200 300 400 500 600 700 spl it ti ng s tr eng th (M P a) time (days)

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2.1.5. Cast 5: S9, S10, BS2, BM2, BL2

The fifth cast was executed on 10-03-2010. The mix was composed of

Portland cement, blast furnace B cement, fly ash and gravel aggregates with a particle size between 4mm and 16mm, Table 2.13 and Fig. 2.13.

Table 2.13: Sieve analysis of Cast 5.

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The air content was 1,5% and the slump of the mix was 180mm. The concrete was delivered by two truck mixers of 6,75m3 and 6,5m3respectively. About 7,5 m3 used for casting the slabs and 4,5 m3for the beams. Each slab was casted in 5 layers. BS1 was casted in 2 layers, BM1 was casted in 3 layers and BL1 was casted in 4 layers. During casting poker vibrators were used to compact the concrete of the slabs and beams and the cubes were compacted on the vibration table. For standard tests 36 cubes (18 out of every truck) were cast on 10-03-2010. The compaction time for the 150mm cubes was 55 seconds. After casting the slabs, beams and cubes were covered with plastic sheets. The cubes were demoulded after one day and the slabs and beams after about one week. All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 7, 28, 55, 77, 90, 127, 181, 190 and 365 days. The slabs and beams were stored in the laboratory (65% RH and 15-20°C). S9 was tested at 77, 78, 79, 82, 83 and 84 days. S10 was tested at 90, 91, 92, 124, 125 and 126 days. BS2 was tested 188 and 190 at days. BM2 was tested 188 and 190 at days. BL2 was tested at 180 and 181 days. The results of the standard tests on the cubes are given in Table 2.15 in which fcc is the concrete compressive strength of the cube and fcspl the concrete

tensile splitting strength of the cube. The development of the concrete compression strength is given in Fig 2.14 and of the splitting tensile strength in Fig. 2.15.

cube age (days) fcc (MPa) fcspl (MPa)

1 7 55,77

2 7 60,42

3 7 64,17

4 7 4,68

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6 7 4,82 7 28 73,09 8 28 75,4 9 28 76,32 10 28 5,85 11 28 5,64 12 28 5,61 13 55 80,22 14 55 80,82 15 55 76,31 16 55 6,07 17 55 5,86 18 55 5,62 19 77 85,96 20 77 82,97 21 77 76,15 22 90 77,47 23 90 81,31 24 90 86,02 25 127 83,63 26 127 79,71 27 127 86,46 28 181 89,62 29 181 99,03 30 181 95,81 31 190 89,38 32 190 87,27 33 190 89,24 34 365 86,28 35 365 80,97 36 365 87,74

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2.1.6. Cast 6: BS3, BM3, BL3

The sixth cast was executed on 22-03-2010. The mix was composed of Portland cement, blast furnace B cement, fly ash and gravel aggregates with a particle size between 4mm and 16mm, Table 2.16 and Fig. 2.16. A retarder and superplastifier were added to the mix.

Table 2.16: Sieve analysis Cast 6.

0 10 20 30 40 50 60 70 80 90 100 0 50 100 150 200 250 300 350 fc ( M P a) time (days) 0 1 2 3 4 5 6 7 0 10 20 30 40 50 60 sp li tt in g s tr en g th ( M P a) time (days)

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The slump of the mix was 160 mm. The concrete was delivered by a truck mixer of 8m3. 4,75 m3 was used for this research of which 4,5 m3for the beams. BS3 was cast in 2 layers, BM3 was cast in 3 layers and BL3 was cast in 4 layers. During casting poker vibrators were used to compact the concrete of the beams and the cubes were compacted on the vibration table. For standard tests 12 cubes were cast on 22-03-2010. The compaction time for the 150mm cubes was 55 seconds. After casting the beams and cubes were covered with plastic sheets. The cubes were demoulded after one day and the beams after about one week. All cubes were stored in the fog room (99% RH and 20°C). All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 7, 28, 37, 57, 171, 182, 184 and 365 days. The beams were stored in the laboratory (65% RH and 15-20°C). BS3 was tested at 182 and 184 days. BM3 was tested at 182 and 184 days. BL3 was tested 171 and 172 at days. The development of the concrete compression strength is given in Fig. 2.17 and of the splitting tensile strength in Fig. 2.18.

Table 2.18: Cube tests cast 6.

1 7 62,63 2 7 60,35 3 7 60,28 4 7 4,91 5 7 4,61 6 7 5,11 7 28 67,28 8 28 74,03 9 28 75,54 10 28 5,55 11 28 5,43 12 28 5,96 13 37 73,50 14 37 81,17

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15 37 82,99 16 37 5,94 17 37 6,21 18 37 5,65 19 57 82,42 20 57 81,86 21 57 83,49 22 57 6,34 23 57 6,03 24 57 6,33 25 171 73,73 26 171 84,55 27 171 85,98 28 182 92,41 29 182 91,87 30 182 94,95 31 184 87,44 32 184 94,29 33 184 85,53 34 365 85,84 35 365 89,04 36 365 88,98 37 365 6,57 38 365 5,94 39 365 6,36

0 10 20 30 40 50 60 70 80 90 100 0 50 100 150 200 250 300 350 fc ( M P a) time (days)

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2.1.7. Cast 7: S11, S12

The seventh cast was executed on 30-06-2010. The mix was composed of blast furnace B cement and gravel aggregates with a particle size between 4mm and 16mm, Table 2.19 and Fig. 2.19. A superplastifier and retarder were added to the mixture.

0 1 2 3 4 5 6 0 50 100 150 200 250 300 350 spl it ti n g st re n gt h (M P a) time (days)

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Table 2.20: Mix composition Cast 7.

The slump of the mix was not measured. The concrete was delivered by a truck mixer of 8,5 m3. Each slab was cast in 5 layers. During casting poker vibrators were used to compact the concrete of the slabs and the cubes were compacted on the vibration table. For standard tests 66 cubes were cast on 30-06-2010. The compaction time for the 150mm cubes was 15 seconds. After casting the slabs and cubes were covered with plastic sheets. The cubes were demoulded after one day and the slabs after 1,5 weeks. All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 7, 28, 56, 90, 122, 130, 177, 210, 365 and 551 days. The slabs were stored in the laboratory (65% RH and 15-20°C). S11 was tested at 90, 91, 92 and 93 days. S12 was tested at 99, 103, 104, 105 and 106 days. The development of the concrete compression strength is given in Fig. 2.20 and of the splitting tensile strength in Fig. 2.21.

1 7 30,62

2 7 31,05

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5 7 2,93 6 7 2,94 7 28 46,96 8 28 46,19 9 28 46,84 10 28 3,78 11 28 3,93 12 28 3,61 13 56 54,16 14 56 52,22 15 56 50,93 16 56 3,95 17 56 4,09 18 90 58,39 19 90 53,28 20 90 52,99 21 90 3,97 22 90 4,03 23 90 4,44 24 122 55,76 25 122 53,68 26 122 54,85 27 130 55,02 28 130 56,21 29 130 55,58 30 177 55,64 31 177 56,32 32 177 57,34 33 177 4,32 34 177 4,37 35 177 4,17 36 210 57,02 37 210 58,94 38 210 56,59 39 210 4,18 40 210 4,13 41 210 4,17 42 365 60,10 43 365 55,46 44 365 61,74 45 365 4,24 46 365 4,52 47 365 4,36 48 551 62,54 49 551 55,46 50 551 60,11

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51 551 4,12

52 551 4,22

53 551 4,53

0 10 20 30 40 50 60 0 100 200 300 400 500 fc ( M P a) time (days) 0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,50 5,00 0 100 200 300 400 500 sp li tt in g s tr en g th ( M P a) time (days)

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The eighth cast was executed on 28-07-2010. The mix was composed of blast furnace B cement and gravel aggregates with a particle size between 4mm and 16mm, Table 2.22 and Fig. 2.22. A superplastifier and retarder were added to the mixture.

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Table 2.23: Mix composition Cast 8

The slump of the mix was not measured. The concrete was delivered by a truck mixer of 8m3. Each slab was cast in 5 layers. During casting poker vibrators were used to compact the concrete of the slabs and the cubes were compacted on the vibration table. For standard tests 40 cubes were cast on 28-07-2010. The compaction time for the 150mm cubes was 15 seconds. After casting the slabs and cubes were covered with plastic sheets. The cubes were demoulded after one day and the slabs after 2 weeks. All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 7, 28, 92, 110, 119, 180, 273 and 365 days. The slabs were stored in the laboratory (65% RH and 15-20°C). S13 was tested at 91, 92, 93, 104, 105 and 106 days. S14 was tested at 110, 111, 112, 114 and 118 days. The development of the concrete compression strength is given in Fig. 2.23 and of the splitting tensile strength in Fig. 2.24.

1 7 25,19 2 7 26,79 3 7 25,89 4 7 2,56 5 7 2,37 6 7 2,41 7 28 40,84 8 28 40,48 9 28 43,08 10 28 3,53 11 28 3,70 12 28 3,60 13 92 54,08 14 92 52,90 15 92 50,72 16 96 51,91 17 96 50,57 18 96 51,05

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20 110 48,43 21 110 52,04 22 119 3,83 23 119 4,42 24 119 4,22 25 180 57,05 26 180 54,99 27 180 53,56 28 180 9,20 29 180 8,75 30 180 9,17 31 273 58,36 32 273 57,57 33 273 56,28 34 273 4,44 35 273 3,76 36 273 4,43 37 365 56,97 38 365 61,26 39 365 56,20 40 365 4,51 41 365 4,50

0 10 20 30 40 50 60 0 50 100 150 200 250 300 350 fc ( M P a) time (days)

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2.1.9. Cast 9: BX3, BX1

The eighth cast was executed on 25-11-2010. The mix was composed of Portland cement, blast furnace cement, fly ash and gravel aggregates with a particle size between 4mm and 16mm, Table 2.25 and Fig. 2.25. A superplastifier and retarder were added to the mixture.

Table 2.25: Sieve analysis Cast 9. 0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,50 5,00 0 50 100 150 200 250 300 350 sp li tt in g s tr en g th ( M P a ) time (days)

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Table 2.26: Mix composition Cast 9

The slump of the mix was 180mm and the air content was not measured. The concrete was delivered by a truck mixer of 9,14m3. Each slab was cast in 5 layers. During casting poker vibrators were used to compact the concrete of the slabs and the cubes were compacted on the vibration table. For standard tests 48 cubes were cast on 25-11-2010. The compaction time for the 150mm cubes was 20 seconds at 140 Hz. After casting the slabs and cubes were covered with plastic sheets. The cubes were

demoulded after one day and the slabs after 5 days. All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 7, 28, 40 and 49days. The slabs were stored in the laboratory (65% RH and 15-20°C). BX3 was tested at 40

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and 41 days. BX1 was tested at 47 and 49 days. The development of the concrete compression strength is given in Fig. 2.26 and of the splitting tensile strength in Fig. 2.27.

1 7 60,35 2 7 65,46 3 7 63,44 4 7 4,60 5 7 5,03 6 7 4,84 7 28 76,55 8 28 71,91 9 28 80,16 10 28 5,91 11 28 6,12 12 28 5,97 13 40 82,65 14 40 82,36 15 40 71,45 16 49 78,14 17 49 83,91 18 49 82,08

0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 30 35 40 45 50 fc ( M P a) time (days)

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2.1.10. Cast 10: BX2

The tenth cast was executed on 09-12-2010. The mix was composed of

Portland Cement, blast furnace cement, fly ash and gravel aggregates of 4mm – 16mm, Table 2.28 and Fig. 2.28. A superplastifier and retarder were added to the mixture.

0,00 1,00 2,00 3,00 4,00 5,00 6,00 7,00 0 5 10 15 20 25 30 sp li tt in g s tr en g th ( M P a) time (days)

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The slump and air content of the mix were not measured. The concrete was delivered by a truck mixer of 3,34m3. The slab was cast in 5 layers. During casting poker vibrators were used to compact the concrete of the slabs and the cubes were

compacted on the vibration table. For standard tests 48 cubes were cast on 09-12-2010. The compaction time for the 150mm cubes was 20 seconds at 140 Hz. After casting the slabs and cubes were covered with plastic sheets. The cubes were demoulded after one day and the slab after 5 days. All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 7, 28 and 41 days. The slab was stored in the laboratory (65% RH and 15-20°C). BX2 was tested at 39 and 41 days. The development of the concrete compression strength is given in Fig. 2.29 and of the splitting tensile strength in Fig. 2.30.

1 7 57,30 2 7 57,34 3 7 59,59 4 7 4,82 5 7 4,30 6 7 4,85 7 28 71,92 8 28 71,50 9 28 68,76 10 28 5,64 11 28 5,55 12 28 6,25 13 41 69,00 14 41 72,68 15 41 69,45 16 41 5,93 17 41 5,60 18 41 5,92

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0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 25 30 35 40 45 50 fc ( M P a) time (days) 0,00 1,00 2,00 3,00 4,00 5,00 6,00 7,00 0 5 10 15 20 25 30 35 40 45 50 sp li tt in g s tr en g th ( M P a) time (days)

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The eleventh cast was executed on 06-01-2011. The mix was composed of blast furnace cement and gravel aggregates of 4mm – 16mm, Table 2.31 and Fig. 2.31. A superplastifier and retarder were added to the mixture.

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The slump of the mix was 170mm. The air content was not measured. The mixture was prepared at a temperature of 8ºC and had a density of 2360 kg/m3. The concrete was delivered by a truck mixer of 8,5 m3. The slabs were cast in 5 layers. During casting poker vibrators were used to compact the concrete of the slabs and the cubes were compacted on the vibration table. For standard tests 30 cubes were cast on 06-01-2011. The compaction time for the 150mm cubes was 10 seconds at 140 Hz. After casting the slabs and cubes were covered with plastic sheets. The cubes were

demoulded after one day and the slabs after 1 week. All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 7, 28, 71 and 85 days. The slabs were stored in the laboratory (65% RH and 15-20°C). S15 was tested at 71, 74, 76 and 77 days. S16 was tested at 85, 88, 90 and 91days. The development of the concrete compression strength is given in Fig. 2.32 and of the splitting tensile strength in Fig. 2.33.

1 7 26,58 2 7 26,71 3 7 26,75 4 7 2,90 5 7 2,72 6 7 2,81 7 28 44,62 8 28 42,44 9 28 45,81 10 28 3,25 11 28 3,84 12 28 3,74 13 71 57,51 14 71 47,67 15 71 51,29 16 71 4,31 17 71 4,30 18 71 4,06

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20 85 54,63

21 85 52,69

22 85 4,77

23 85 4,35

24 85 4,09

0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 80 90 fc (M P a) time (days) 0,00 1,00 2,00 3,00 4,00 5,00 6,00 0 10 20 30 40 50 60 70 80 90 spl it ti ng st re n gt h (M P a ) time (days)

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2.1.12. Cast 12: S17, S18

The twelfth cast was executed on 01-02-2011. The mix was composed of blast furnace cement and gravel aggregates of 4mm – 16mm, Table 2.34 and Fig. 2.34. A superplastifier and retarder were added to the mixture.

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The slump of the mix was 170mm. The air content was not measured. The mixture was prepared at a temperature of 10ºC and had a density of 2320 kg/m3. The concrete was delivered by a truck mixer of 9 m3. The slabs were cast in 5 layers. During casting poker vibrators were used to compact the concrete of the slabs and the cubes were compacted on the vibration table. For standard tests 30 cubes were cast on 01-02-2011. The compaction time for the 150mm cubes was 10 seconds at 152 Hz. After casting the slabs and cubes were covered with plastic sheets. The cubes were

demoulded after one day and the slabs after more than 1 month. All cubes were stored in the fog room (99% RH and 20°C). The cubes were tested at an age of 7, 25, 28, 69, 113 and 120 days. The slabs were stored in the laboratory (65% RH and 15-20°C). S17 was tested at 69, 70, 98 and 108 days. S18 was tested at 118, 119 and 120 days. The development of the concrete compression strength is given in Fig. 2.35 and of the splitting tensile strength in Fig. 2.36.

1 7 21,63 2 7 21,44 3 7 21,16 4 7 2,41 5 7 2,43 6 7 2,41 7 25 40,21 8 25 41,84 9 25 39,40 10 25 3,55 11 25 3,44 12 25 3,43 13 28 39,29 14 28 40,78 15 28 40,71 16 28 3,45 17 28 3,41 18 28 3,40 19 69 48,62

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20 69 50,80 21 69 48,76 22 69 3,57 23 69 4,08 24 69 3,48 25 113 55,68 26 113 55,94 27 113 53,28 28 120 52,36 29 120 53,16 30 120 50,83 31 120 4,48 32 120 4,47 33 120 4,69

0 10 20 30 40 50 60 0 20 40 60 80 100 120 fc ( M P a) time (days)

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Fig. 2.36: Development of splitting tensile strength, cast 12. 0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,50 5,00 0 20 40 60 80 100 120 sp li tt in g s tr en g th ( M P a) time (days)

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2.2. Steel

Ribbed and plain reinforcing bars of 10 and 20mm diameter were used. The stress-strain diagrams as tested by Exova are given in Fig. 2.37, Fig. 2.38, Fig. 2.40 and Fig. 2.39.

Fig. 2.37: Stress-strain diagram for plain bar of 10mm diameter.

Fig. 2.38: Stress-strain diagram for ribbed bar of diameter 10mm. 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 0, 0000 0, 0010 0, 0020 0, 0030 0, 0040 0, 0050 0, 0060 0, 0070 0, 0080 0, 0090 0, 0100 0, 0110 0, 0120 0, 0130 0, 0140 0, 0150 0, 0160 0, 0170 0, 0180 0, 0190 0, 0200 0, 0210 0, 0220 0, 0230 0, 0240 0, 0250 0, 0260 0, 0270 0, 0280 0, 0290 0, 0300 0, 0310 0, 0320 0, 0330 0, 0340 0, 0350 S tr es s [ M P a] Strain [-] 0 50 100 150 200 250 300 350 400 450 500 550 600 650 0, 0000 0, 0020 0, 0040 0, 0060 0, 0080 0, 0100 0, 0120 0, 0140 0, 0160 0, 0180 0, 0200 0, 0220 0, 0240 0, 0260 0, 0280 0, 0300 0, 0320 0, 0340 0, 0360 0, 0380 0, 0400 0, 0420 0, 0440 0, 0460 0, 0480 0, 0500 0, 0520 0, 0540 0, 0560 0, 0580 0, 0600 0, 0620 0, 0640 0, 0660 0, 0680 0, 0700 0, 0720 0, 0740 0, 0760 0, 0780 0, 0800 S tr es s [M P a] Strain [-]

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Fig. 2.39: Stress-strain diagram for plain bar of 20mm diameter.

Fig. 2.40: Stress-strain diagram for ribbed bar of 20mm diameter.

0 50 100 150 200 250 300 350 400 450 500 550 600 650 0 ,0 0 0 0 0 ,0 0 2 0 0 ,0 0 4 0 0 ,0 0 6 0 0 ,0 0 8 0 0 ,0 1 0 0 0 ,0 1 2 0 0 ,0 1 4 0 0 ,0 1 6 0 0 ,0 1 8 0 0 ,0 2 0 0 0 ,0 2 2 0 0 ,0 2 4 0 0 ,0 2 6 0 0 ,0 2 8 0 0 ,0 3 0 0 0 ,0 3 2 0 0 ,0 3 4 0 0 ,0 3 6 0 0 ,0 3 8 0 0 ,0 4 0 0 S tr es s [ M P a] Strain [-] 0 50 100 150 200 250 300 350 400 450 500 550 600 650 0 ,0 0 0 0 0 ,0 0 5 0 0 ,0 1 0 0 0 ,0 1 5 0 0 ,0 2 0 0 0 ,0 2 5 0 0 ,0 3 0 0 0 ,0 3 5 0 0 ,0 4 0 0 0 ,0 4 5 0 0 ,0 5 0 0 0 ,0 5 5 0 0 ,0 6 0 0 0 ,0 6 5 0 0 ,0 7 0 0 0 ,0 7 5 0 0 ,0 8 0 0 0 ,0 8 5 0 0 ,0 9 0 0 0 ,0 9 5 0 0 ,1 0 0 0 0 ,1 0 5 0 0 ,1 1 0 0 0 ,1 1 5 0 0 ,1 2 0 0 0 ,1 2 5 0 0 ,1 3 0 0 0 ,1 3 5 0 0 ,1 4 0 0 0 ,1 4 5 0 0 ,1 5 0 0 S tr es s [ M P a] Strain [-]

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3. Specimens

In total 18 slabs with a width of 2,5m were cast, named S1 – S18. Additionally, 3 slab strips of 0,5m width (BS1 – BS3) along with 3 slab strips of 1m width (BM1 – BM3), 3 slab strips of 1,5m width (BL1 – BL3) were cast and 3 slab strips of 2m width (BX1 – BX3). The dimensions of the slabs are presented in Fig. 3.1 and the dimensions of the beams BS, BM, BL, BX in Fig. 3.2, Fig. 3.3, Fig. 3.4 and Fig. 3.5.

Fig. 3.1: Dimensions of slabs S1 – S18.

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Fig. 3.3: Dimensions of BM1 – BM3.

Fig. 3.4: Dimensions of BL1 – BL3.

Fig. 3.5: Dimensions of BX1 – BX3.

The layout of the reinforcement of S1 and S2 is presented in Fig. 3.6. The layout of the reinforcement of S3, S5, S6, S7, S8, S9 and S10 is presented in Fig. 3.7 and the

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reinforcement of S4 in Fig. 3.8. The layout of the reinforcement (plain bars) of S11, S12, S13 and S14 is shown in Fig. 3.9. The layout of the reinforcement of S15, S16, S17 and S18 is shown in Fig. 3.10. The layout of BS is shown in Fig. 3.11, of BM in Fig. 3.12 of BL in Fig. 3.13 and of BX in Fig. 3.14.

Fig. 3.6: Reinforcement layout for S1 and S2.

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Fig. 3.8: Reinforcement layout for S4.

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Fig. 3.10: Reinforcement layout for S15-S18.

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Fig. 3.12: Reinforcement layout of BM.

Fig. 3.13: Reinforcement layout of BL.

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4. Loading scheme and measuring devices

All specimens were loaded through a concentrated point load. The size of the loading plate, the shear span and the distance along the width were variable. Slabs S1 – S14 and slab strips BS1 – BX3 are supported by a line support. Side views of the test setup are presented in Fig. 4.1 and Fig. 4.2. The top view is presented in Fig. 4.3 and the front view in Fig. 4.4. Slabs S15 – S18 are supported on three elastomeric bearings. Drawings of the test setup supported by bearings are shown in Fig. 4.5, Fig. 4.6 and Fig. 4.7.

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Fig. 4.2: Test setup, loading at continuous support, slab on line supports.

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Fig. 4.4: Test setup, front view, slab on line supports.

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Fig. 4.6: Test setup, loading at continuous support, slab on bearings.

Fig. 4.7: Test setup, front view, slab on bearings.

During the course of testing the forces in the load cells were measured. Crack widths were measured by using a crack width comparator (0,05mm – 10mm). The displacements were measured by using lasers. Fig. 4.8 shows the layout of the lasers as used on S1. The sketch is not to scale. Lasers 1, 2, 3, 14, 15 and 16 were placed over the support and lasers 4 to 13 were placed around the load, depending on the

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position of the load. During S1T1 and S1T2 lasers 17 and 18 were placed on the steel profile of the line support. During S1T3 – S1T6 lasers 17 and 18 were placed over the support at a position along the width corresponding to the center of the load. Fig. 4.9 shows the layout of the lasers used on S2 – S10, S12 - S14 when the load was placed at the simple support. Lasers 19 and 20 were placed on the bottom face of the slab. Fig. 4.10 shows the layout of the lasers used on S2 – S10, S12 - S14 when the load was placed at the continuous support. Again, lasers 19 and 20 were placed on the bottom face of the slab. Fig. 4.11 shows the layout of the lasers as they are used on S11. The layout of the lasers on S15 to S18 loaded near the simple support is shown in Fig. 4.12 (lasers on top face of slab), Fig. 4.13 (detailing) and Fig. 4.14 (lasers on bottom face of slab). The laser layout for loading near the continuous support is shown in Fig. 4.15 (lasers on top face of slab) and Fig. 4.16 (lasers on bottom face of slab). In S16 – S18, lasers were used to measure the deflection of the steel HEM300 beam as well as the laboratory floor. Fewer lasers were available for measuring, and therefore a layout as shown in Fig. 4.17 is used. This layout is however changed for every test, as described in the sections describing these experiments.

Fig. 4.18 and Fig. 4.19 show the layout of the lasers on BS. Fig. 4.20 and Fig. 4.21 show the layout of the lasers on BM. Fig. 4.22 and Fig. 4.23 show the layout of the lasers on BL. Fig. 4.24 and Fig. 4.25 show the layout of the lasers on BX.

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Fig. 4.9: Layout of lasers on S2 – S10, S12 - S14 for load at SS.

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Fig. 4.11: Layout of lasers on S11.

Fig. 4.12: Layout of lasers on top side of S15 – S18, loading at simple support.

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Fig. 4.14: Layout of lasers on bottom side of S15 – S18, loading at simple support.

Fig. 4.15: Layout of lasers on top side of S15 – S18, loading at continuous support.

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Fig. 4.17: Example of layout of lasers as used in S16T3.

Fig. 4.18: Layout of lasers on BS, load at SS

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Fig. 4.20: Layout of lasers on BM, load at SS.

Fig. 4.21: Layout of lasers on BM, load at CS.

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Fig. 4.23: Layout of lasers on BL, load at CS.

Fig. 4.24: Layout of lasers on BX, load at SS.

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The load is applied in increments equal to an increment of 200kN. The load consists of a hydraulic jack with a 2000kN capacity. The measured failure load is the load at which the force decreases for an increasing displacement. The load is kept constant while marking the cracks.

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5. Presentation of the results

5.1. Introduction

This chapter contains all the experimental results. For each specimen the same set of results is reported. A brief explanation of this procedure is included here. First the data covering all tests on one specimen are presented:

1. The basic variables of the specimen.

2. The compressive strength of the cores drilled out of the specimens.

Then, the following series of data is represented for every test carried out on the same specimen:

3. The basic variables of the considered test.

4. Description of the observations made during testing and pictures of the failure mode.

5. The force-time diagram. This diagram represents the loading scheme on the specimen.

6. The force-displacement diagram. The displacement is measured as the mean value of the displacement of the lasers around the load. This eliminates the effect of the local crushing of the concrete under the load plate.

7. The force-time diagram at the prestressing bars.

8. The deflection profiles at selected points in time over the span length. 9. The deflection profiles at selected points in time over the simple support. 10.The deflection profiles at selected points in time over the continuous support. For the slabs supported by elastomeric bearings, the following data are presented as well:

11.The forces over the simple support at selected points in time. These forces were measured by load cells placed underneath the elastomeric bearings. 12.The forces over the continuous support at selected points in time. Finally the following data representing all tests on one specimen are presented:

11.The measured cracked width along the support. 12.The measured crack widths.

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5.2.1. S1

1. The basic variables of the specimen.

S1 was cast on 08-10-2009. S1 has a longitudinal reinforcement of φ20 – 125mm and a non-principal longitudinal reinforcement of φ10 – 250mm. In other words, ρl =

0,996% and ρt = 0,132%. The average compressive strength at the age of testing was

fc’ = 35,7 MPa. A load plate of 200mm x 200mm was used. 10mm of P50 Nevima felt

was used for the line support. The heart of the plywood coincided with the heart of the steel beam. The deflection at the supports due to the compression of the felt was not measured and hence a correction of the laser measurements over the support could not be made.

2. The compressive strength of the cores drilled out of the specimens.

All cylinders had h=10cm. The data of the compressive tests are in Table 5.1. Table 5.1.: Compressive strength of cores drilled out of S1. Cylinder φ (cm) Result [kN] Strength [Mpa] Damaged?

S1-1 10.2 282.5 34.5 Cracks visible on front face

S1-2 10.2 295.7 36.19 Cracks visible on front and

side faces S1-3 9.855 346.6 45.48 not visible

5.2.1.1 S1T1

3. The basic variables of the considered test.

Date: 05-11-2009

Load position: a = 600mm , br = 1250mm, at simple support.

4. The observations made during testing.

At 700 kN a flexural crack appeared at the front face. At 850 kN this crack had a width of 1mm. Failure occurred at 954 kN. The width of the crack at the front face was then 1,7 – 1,8mm, Fig. 5.1. On the bottom face the flexural cracking pattern could be observed, Fig. 5.2. The main cracks appeared around the load and ran towards and away from the support. The load plate sank into the top face of the concrete, Fig. 5.3.

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Fig. 5.1: Cracking pattern on bottom – S1T1.

Fig. 5.2: Cracking at front face – S1T1.

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Fig. 5.4: Loading scheme on S1T1.

6. The force-displacement diagram.

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7. The force-time diagram at the prestressing bars.

Fig. 5.6: Loading scheme at prestressing bars S1T1.

8. The deflection profiles at selected points in time over the span length.

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Fig. 5.8: Deflection profiles over simple support S1T1.

10.The deflection profiles at selected points in time over the continuous support.

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5.2.1.2 S1T2

Date: 13-11-2009

Load position: a = 600mm , br = 1250mm, at continuous support.

4. The observations made during testing

The first cracks appeared on the bottom around the position of the load at 200kN. At 400kN more flexural cracks were visible on the bottom face and the first flexural cracks appeared at the side face. At 600kN a further development of the flexural cracking pattern could be observed on the bottom face and the first crack on the front face was visible. At 800kN the bottom face showed a fully developed flexural

cracking pattern. At 900kN the crack at the front face was 0,6mm. When the load reached 900kN for the second time the concrete was touching the plywood of the support. Failure happened at 1023kN. The largest observed crack was a flexural crack on the bottom face with a width of 2,5mm. This crack was located along the middle of the width and extended over more than half of the span length. At failure the loading plate sank into the top surface of the concrete. The measurements of laser 12 have not been taken into consideration for the deflection plot, as the measurement results appeared unstable.

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Fig. 5.11: Cracking at bottom face at failure – S1T2.

5. The force-time diagram.

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Fig. 5.13: Force – displacement diagram S1T2.

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Fig. 5.15: Deflection over span, S1T2.

9. The deflection profiles at selected points in time over the simple support.

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Fig. 5.17: Deflection at continuous support S1T2.

11.The measured cracked width along the support.

Table 5.2: Measured loaded/cracked width over support of S1.

beff

S1T1 1,8m S1T2 1,7m

12.The measured crack widths.

Table 5.3: Overview of crack widths S1

F (kN) wmax(mm) where? S1T1 954 1,7 front face S1T2 900 0,6 front face 1023 2,5 bottom face

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fc’ = 35,7 MPa. A load plate of 300mm x 300mm was used. 10mm of P50 Nevima felt

was used for the line support. The heart of the plywood coincided with the heart of the steel beam.

The cylinder had h=10cm. The data of the compressive tests are in Table 5.4. Table 5.4.: Compressive strength of cores drilled out of S1. Cylinder φ (cm) Result [kN] Strength [Mpa] Damaged?

S2-1 9.83 376.2 49.57 not visible

5.2.2.1 S2T1

Date: 03-12-2009

Load position: a = 600mm, br = 1250mm, at simple support.

At 200kN a crack under a 45° angel appeared at the bottom face together with two cracks parallel to it. Some flexural cracks were visible on the bottom face. Shrinkage cracks were marked at the side face. At 400kN more inclined cracks were observed on the bottom of the slab along with the further development of the flexural cracking pattern which was not spread out over the full bottom face. A crack close to the continuous support was visible. At 600kN flexural cracks up to more than half of the span length (but not up to the continuous support) were visible at the east side and at the west side inclined flexural cracks developed. At the front face three pronounced cracks were visible. At the side face only flexural cracks were visible. At 800kN more flexural cracks were observed. The width of the cracks was about 0,25mm and locally 0,6mm. The cracks at the front face did not grow. At 1000kN the crack at the bottom face was 1,5mm wide. At 1200kN this crack was 2mm wide and continued on the side face. The peak load was 1374kN. The measurements of laser 20 ran out of the range during the course of the experiments. Therefore, the settlement of the simple support could only be corrected for in the measurement range.

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Fig. 5.18: Cracks on bottom after S2T1.

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Fig. 5.20: Loading scheme S2T1.

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Fig. 5.22: Loading at prestressing bars S2T1.

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Fig. 5.24: Deflection at simple support S2T1.

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5.2.2.2 S2T4

Date: 14-12-2009

Load position: a = 600mm, br = 1250mm, at continuous support.

At 200kN connections between existing flexural cracks appeared. Nothing was visible at the side face. A new crack appeared on the front face starting from the bottom face. At 400kN inclined cracks appeared at the bottom on the west side and a few more flexural cracks appeared at the east side. The side and front faces remained unchanged. At 600kN a flexural crack going towards the side and the simple support was visible on the west side and an inclined crack and more flexural cracks were visible at the east side. Some flexural cracks appeared at the side face close to the bottom. Flexural cracks were also visible at the front face. At 800kN a star-shaped pattern was visible around the load with a maximum crack width of 0,4mm. Flexural cracks were visible at the side face. The maximum crack width at the front face was 0,2mm. After 950kN the load decreased. The concrete appeared to touch the plywood and possible made a new compression strut. At 1387kN the crack at the front face was 0,7mm wide and an inclined crack at the bottom opened up. The maximum load was 1421kN. Laser 20 was out of its measurement range and laser 19 left its range during the experiment. The settlement of the support could thus not be appropriately corrected for.

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Fig. 5.29: Loading scheme at prestressing bars S2T4.

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Fig. 5.31: Deflection at simple support S2T4.

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Table 5.5: Measured effective width along support S2

beff

S2T1 1,8 - 2,13m S2T4 1,95m

Table 5.6: Measured crack widths S2 F (kN) wmax (mm) where? S2T1 800 0,6 bottom face 1000 1,5 bottom face 1200 2 bottom face 1374 _≈ 30 bottom face S2T4 800 0,4 bottom face 1387 0,7 front face 1421 _≈ 20 bottom face

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fc’ = 50,7MPa. A load plate of 300mm x 300mm was used. 10mm of 950 Nevima felt

was used for the line support. The plywood was eccentric from the heart of the support to create more room for rotation.

All cylinders were 10cm high.

Table 5.7: Compressive strength cores S3 Cylinder φ (cm) Result [kN] Strength [Mpa] Damaged?

S3-1 9.95 474 60.96 not visible

S3-2 9.95 443.4 57.02 Cracks visible on front and

side faces

5.2.3.1 S3T1

Date: 22-01-2010

Load position: a = 600mm, br = 1250mm, at simple support.

The first two flexural cracks were visible at 200kN. At 400kN inclined cracks appeared mainly at the west side. These cracks had a width of 0,4mm up to 1mm locally. At the west side face two cracks were visible. At 600kN inclined cracks were visible at the west side and straight cracks at the east side. The cracks at the west side were 0,6mm. Around the load they were 0,8mm and locally 2mm. At the front face two cracks with a maximum width of 0,9mm appeared. At the west side face slightly inclined cracks were visible. At 800kN the cracks at the front face were 3mm at the bottom and 1,5mm over the depth of the specimen. Flexural cracks were observed at the west side. At the east side sime slightly inclined cracks appeared. At the bottom face the cracks towards the west side were inclined and the cracks towards the east side ran parallel to the support. At 1000kN the cracks at the front face were about 1 – 1,5mm over the depth of the specimen. The cracks at the west side were 0,35mm. The bottom face showed the same behavior as at the previous loading stages. At 1200kN the specimen was lying on the plywood. At 1347kN the crack at the front face ran

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over the full depth. At 1371kN the maximum value was reached and a loud noise was heard. At 1240kN a crack along the support and shear cracks appeared. After failure the crack in the middle of the bottom face was 3mm wide and the crack towards the support 0,35mm. The crack at the front face was 2mm wide. The cracks at the side face starting from the support were 0,9 – 1mm wide.

Fig. 5.33: Failure pattern at bottom after S3T1 (red).

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Fig. 5.35: Crack at west face S3T1.

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Fig. 5.38: Loading at prestressing S3T1.

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Fig. 5.40: Deflection over simple support S3T1.

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5.2.3.2 S3T4

Date: 28-01-2010

Load position: a = 600mm, br = 1250mm, at continuous support.

At 200kN a crack at the east side face was visible. At 400kN a star-shaped patern of about 3 cracks was visible around the load at the bottom face. A second crack at the east side face appeared close to the support. At 600kN inclined cracks appeared at the bottom side. The maximum crack width was 0,1 – 0,15mm close to the support. At both side faces some more cracking was observed. At 800kN the crack width at the bottom face was 0,2mm. The side faces had a few flexural cracks of maximum 0,05mm. After failure at 1337kN the cracks at the bottom were 0,45 – 0,5mm around the load. A crack appeared at the front face from top to bottom with a width of 0,05mm. An unexpected shear crack appeared at the east side at failure. Laser 19 ran out of its measurement range during the experiment.

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Fig. 5.43: Cracking at bottom S3T4.

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Fig. 5.46: Loading at prestressing bars S3T4.

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Fig. 5.48: Deflection plot over simple support S3T4.

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Table 5.8: Effective width S3

beff

S3T1 1,68m

S3T4 1,91m: 0,66W + 1,25O

Table 5.9: Measured crack widths S3. F (kN) wmax (mm) where?

S3T1 400kN 0,4 bottom face - inclined crack

1 local max on bottom face

600kN 0,6 bottom face - inclined crack

0,8 bottom face around load

2 local max on bottom face

0,9 front face

800kN 1,5 front face over length

3 front face bottom

1000kN 1 - 1,5 front face over length

0,35 side face inclined crack

1240 3 bottom face - longitudinal crack 0,35 bottom face - towards support

2 front face

0,9 - 1 side face inclined crack S3T4 600kN 0,1 - 0,15 bottom face - around load

800kN 0,2 bottom face - around load

0,05 side face flexural crack

1000kN 0,45 - 0,5 bottom face - around load

0,05 front face

13.The dimensions of the dominant shear cracks at the side face.

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Table 5.10: Dimensions of shear cracks S3 S3T4 linclined 46cm hinclined 28,5cm lstraight 49cm from bottom 0cm nn 5cm nn 10cm 2mm 15cm 5mm 20cm 1,5mm 25cm 6mm

(105)

5.2.4. S4

S4 was cast on 20-11-2009. S4 has a longitudinal reinforcement of φ20 – 125mm and a non-principal longitudinal reinforcement of φ10 – 250mm, locally increased to φ10 –125mm. In other words, ρl = 0,996% and ρt = 0,182%. The average compressive

strength at the age of testing was fc’ = 50,7MPa. A load plate of 300mm x 300mm

was used. 15mm of N100 Nevima felt was used for the line support. The plywood was eccentric from the heart of the support to create more room for rotation.

Table 5.11: Compressive strength cores from S4.

Cylinder φ (cm) h (cm) Result [kN] Strength [Mpa] Damaged?

S4-1 9.98 9.8 392.7 50.20 not visible S4-2 9.98 9.8 458.8 58.65 not visible

S4-3 10 10 311.6 39.67 not visible, but

value

low

S4-4 10 10 438.3 55.81 not visible

5.2.4.1 S4T1

Date: 04-02-2010

Load position: a = 600mm, br = 438mm west, at simple support.

During this test the video card of the computer which reads and saves the data crashed. After this crash a jump in all values of the data was found. This effect was manually taken out of the raw data. At 200kN two very small cracks were observed at the bottom of the slab. At 400kN a crack of 0,15mm was observed at the side face. Flexural cracks at the side and bottom faces were observed. At 600kN the crack at the west side face was 0,15mm. At the bottom face cracks of 0,20 – 0,25mm wide were observed running towards the east side face. At 800kN the crack at the side face was 0,4mm wide. The first shear crack was visible. At 990kN the second shear crack was visible. Failure occurred at 1160kN. The maximum crack width at the top face is 0,45mm. At the front face the maximum crack width is 0,8mm. The width of the shear crack at the west side face was 4mm. The crack at the bottom face was maximum 0,6mm wide. Laser 19 ran out of its measuring range during the experiment.

(106)

Fig. 5.51: Cracks at top face S4T1 (blue).

Fig. 5.52: Cracks at front face S4T1.

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Fig. 5.54: Cracks at bottom face S4T1.

5. The force-time diagram

Shear Tests of Reinforced Concrete Slabs: Experimental Data of Undamaged Slabs. Concept v. 26-10-2012

Shear tests of Reinforced Concrete Slabs

Experimental data of Undamaged Slabs

Shear tests of Reinforced Concrete Slabs

Experimental data of Undamaged Slabs

Contents

1. Introduction

2.

Material properties

2.1. Concrete mix

2.2. Steel

3.

Specimens

4.

Loading scheme and measuring devices

5. Presentation of the results

5.1. Introduction

5.2.1.1

S1T1

5.2.1.2

S1T2

5.2.2.1

S2T1

5.2.2.2

S2T4

5.2.3.1

S3T1

5.2.3.2

S3T4

5.2.4.1

S4T1