Shear-torsion tests on 400 mm hollow core floor

VTT RESEA

RCH N

OTES 2274Shear-torsion tests on 400 m

m hollow

core floor

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ISBN 951–38–6518–5 (URL: http://www.vtt.fi/inf/pdf/)ISSN 1455–0865 (URL: http://www.vtt.fi/inf/pdf/)

ESPOO 2004 VTT RESEARCH NOTES 2274

Fifteen load tests on a floor comprising four prestressed hollow core slabswere carried out to clarify the interaction of shear and torsion. The slabswere 400 mm in depth and 7 m in length. The ends of the slabs were simplysupported on concrete beams. The loads in each test comprised one or twoconcentrated loads close to the support.

In twelve tests the loads were limited to a typical service load. Inthese tests the behaviour of the floor was relatively linear. In three teststhe floor was loaded to failure. The observed failure loads were 25–97%higher than in a reference test on a single slab unit. In the first failuretest with one point load, the failure mode was punching. In other twotests with two point loads, as well as in the reference test with one pointload, the failure was a typical shear – torsion failure.

Matti Pajari

Shear-torsion tests on 400 mmhollow core floor

1211

12

3 45

67

89

10

VTT TIEDOTTEITA � RESEARCH NOTES 2274

Shear-torsion tests on 400 mm hollow core floor

Matti Pajari VTT Building and Transport

ISBN 951�38�6518�5 (URL: http://www.vtt.fi/inf/pdf/) ISSN 1455�0865 (URL: http://www.vtt.fi/inf/pdf/) Copyright © VTT 2004

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Technical editing Leena Ukskoski

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Pajari, Matti. Shear-torsion tests on 400 mm hollow core floor. Espoo 2004. VTT Tiedotteita � Research Notes 2274. 30 p. + app. 82 p.

Keywords shear tests, torsion tests, hollow core slabs, floors, testing, test specimens, load testing,failure loads, load distribution, concrete, precast, prestressed, structure

Abstract Fifteen load tests on a floor comprising four prestressed hollow core slabs were carried out to clarify the interaction of shear and torsion. The slabs were 400 mm in depth, 1.2 m in width and 7 m in length. The ends of the slabs were simply supported on concrete beams. The loads in each test comprised one or two concentrated loads close to the support.

In twelve tests the loads were limited to a typical service load or to a somewhat higher load. In these tests the behaviour of the floor was relatively linear and no sign of failure could be observed. In three tests the floor was loaded to a local failure. The observed failure loads were 25�97% higher than in a reference test on a single slab unit with identical support conditions. In the first failure test with one point load the failure mode was punching. In other two tests with two point loads, as well as in the reference test with one point load, the failure was a typical shear-torsion failure.

As a subtask of HOLCOTORS project, the test results have been used by Chalmers University of Technology for calibration of computerized calculation methods they have developed. This work is published elsewhere. Therefore, the present design practice has not been evaluated here in view of the obtained results.

Preface In 2002�2004, a European research project named HOLCOTORS was carried out. It aimed at providing numerical methods for analysis and simplified methods for design of prestressed hollow core floors subjected to shear and torsion. The calculation models were developed by Chalmers University of Technology, Sweden. The tests used for verification of the models were carried out and documented by VTT, Finland. The researchers in the involved research institutes were

Helen Broo Chalmers Björn Engström Chalmers Karin Lundgren Chalmers Matti Pajari VTT Mario Plos Chalmers.

In addition to the researchers, the following representatives of the industrial partners participated in the work as members of the steering group and by participating in the workshops organised on the day before the steering group meetings:

Olli Korander Consolis Technology, Finland, Chairman Arnold van Acker Belgium Willem Bekker Echo, Belgium David Fernandez-Ordonez Castelo, Spain Ronald Klein-Holte BVSH (VBI) The Netherlands Gösta Lindström Strängbetong, Sweden Aad van Paassen BVSH (VBI), The Netherlands Nordy Robbens Echo, Belgium Bart Thijs Echo, Belgium Jan de Wit IPHA (Dycore), The Netherlands Javier Zubia Castelo, Spain.

Gösta Lindström also worked in close co-operation with the researchers, participated in extra workshops between the steering group meetings and made proposals for the future design practice.

The experimental part of the research project, a part of which is documented in this report, was financed by the Fifth Framework Programme of European Commission (Competitive and Sustainable Growth, Contract Nº G6RD-CT-2001-00641); Inter-national Prestressed Hollow Core Association, Bundesverband Spannbeton-Hohlplatten, Castelo, Consolis, Echo, Strängbetong, and VTT. The test specimens were provided by Parma Betonila, Finland.

4

Contents

Abstract..............................................................................................................................3

Preface ...............................................................................................................................4

1. Introduction..................................................................................................................6

2. Test arrangements ........................................................................................................7

3. Results of load tests ...................................................................................................14 3.1 Tests with service load .....................................................................................14 3.2 Failure tests.......................................................................................................18

4. Strength of concrete ...................................................................................................24

5. Analysis of results......................................................................................................26

6. Discussion..................................................................................................................29

References .......................................................................................................................30

Appendices A Photographs

B Measured slab cross-sections

C Measured forces, strains and displacements

D Initial part of load-deflection curves

5

1. Introduction

The tests documented in this report were planned to clarify the effect of shear and torsion on the deflection and resistance of a floor made of prestressed hollow core slab units. By placing the load close to the support, bending failure modes were eliminated.

In all figures of this report, the measures are given in millimetres unless otherwise specified.

6

2. Test arrangements

12 tests with service load were carried out. In these tests the floor was subjected to one point load which was increased monotonously until a certain predefined limit load was achieved. After that the load was moved to another position and the same procedure was repeated. All positions of the service point load are shown in Fig. 1.a.

After the service load tests the floor was loaded to failure in three tests. In the first test there was one point load, in the second and third test two point loads. Their location is illustrated in Fig. 1.b. Some characteristics of the test specimens are given in Table 1. Different tests are identified by symbol PF400:x where x is the number of the test shown in Fig. 1.

1211

1 23 4

5 6 7

8910

a)

13

15

14

b)

Fig. 1. General view on loading arrangements. a) Location of point load in tests PF400:1�12. b) Location of point loads in tests PF400:13�15.

Table 1. Characteristics of slab units in test PF400.

Thickness mm

Strands Initial prestress MPa

Length m

Cast

400 11 d 12.5 1000 7080 26.6.2002

For comparison, a load test called ST400E1M with similar support conditions as in the present floor but with only one slab unit was carried out, see Fig. 2. This test has been reported elsewhere [3].

7

8

P

e

Fig. 2. Loading arrangements in test ST400E1M [3].

The material data provided by the manufacturer of the slab units are collected in Table 2.

Table 2. Data provided by the slab manufacturer.

Concrete K60 Cement CEM I 52,5 R Cement kg/m3 270 Water l/m3 145 Maximum aggregate size # [mm] 16 Number of aggregates 4 Strands - strength/0.2% yield strength [MPa] - initial prestress [MPa]

1860 / 1640

1000

The nominal cross-section of the slab units is given in Fig. 3 and the measured geometry in Appendix B. For the shape of the hollow cores see also Fig. 34. The geometry of the supporting beams is specified in Fig. 6.a and the arrangements at the support in Figs 6.b and 7.

109 114 228

175.5 283 283 283 175.56

1840

560

5

3

619

Chamfer 12x12

1200

36

44

55400

55262

A B B A

270.5

c=3046.5 283 283

25

270.5 46.52525252525

Fig. 3. Nominal cross-section and location of strands in slab units. c refers to concrete cover below the strand.

The supporting beams were placed on the floor of the laboratory without any smoothing material. The slab units were placed on the beams. The longitudinal joints were grouted on the 16th of September 2002. On the next day the joints were precracked by wedges, see Figs 1�4 in App. A. The crack widths measured after the precracking and before casting the tie beams are shown in Fig. 4.

4

3

2

1

0.34

0.30

0.28

0.22

0.26

0.36

Fig. 4. Crack width after precracking.

9

The tie beams were cast on the 18th of September 2002.

The support conditions and test arrangements are roughly presented in Fig. 5 and in more detail in Figs 6�11.

200

7080 (length of slab)

7

P

I Location of load P/2 in test I (I = 14, 15)

Location of vertical transducer J

Concrete elementL = 5000

6

I Location of load P in test I (I = 1, ... ,13)

5

43,142

9

1,13

1011,1512

40

1

2

3

4

1112

1314

15

1617

1819

20

2122

2324

25

2627

2829

42

41

40

39

38

37

36

35

34

33

32

31

63

2

4

5

1

60200 760JK Location of horizontal transducer K

20

47

46

45

44

43

20

40

14

15

8

30

Fig. 5. Numbering and location of horizontal transducers 1�6 and vertical transducers 11�47 as well as location of loads in tests PF400:1�PF400:15.

10

570

400

200 150150

300

400100 100

Rebarsd 10 c/c 300

2 d 10

2 d 16

2 holes for lifting

Concrete K30

a)

80100

30

Cast-in-situ concrete K30

2 rebars d 16 L = 4750

16 rebars d 10c/c 300L = 400 + 300

200

10060Plywood board

30x50x80under webs,2 pc./s lab end

50

Thin plastic sheet

b)

Fig. 6. a) Supporting beam, length = 5.0 m. b) Arrangements at support. See also Fig. 7. d x refers to a reinforcing bar with diameter x.

1

2

3

4

1200AA

a)

30

200

100100

70

Tie bar inlongitudinal joint

A A

160

70230

b)

Fig. 7. Tie reinforcement in longitudinal joints. a) Plan. b) Elevation.

11

2355

Location of vertical transducer J Location of load P 40

3

4

60200

208318001517

11551245

883600317

2355208318001517

11551245

883600317

2355

1155

Symmetric

760200

40

1245

45 45Centre line of floor45

Symm. 453176008831155

151718002083

Symm.

2355

1

2

Location of load P/2

Fig. 8. Location of loads P and vertical transducers. See Fig. 5 for numbering of transducers.

P

Gypsum

Steel plate10x100x100

Fig. 9. Arrangements below one point load.

12

13

P e

Gypsum

Roller barSteel plate10x100x100

CL

Gypsum

Bar welded to steel plateSteel plate10x100x100

e

Fig. 10. Arrangements when two point loads are applied.

3

70

70

Strain gauge

Centre line of joint

Centre line of joint

9 (10)

7 (8)

Fig. 11. Location of strain gauges 7�10 fixed to horizontal steel bars in tie beam at the loaded end. See also Fig. 3 in App. A. The numbers in parentheses refer to gauges glued to the lower bar.

The tests were carried out by keeping the rate of elongation of the actuator at a predefined level. When necessary, this level was shifted. The rate of loading was measured. It is given in App. C for each test.

3. Results of load tests

3.1 Tests with service load

In tests PF400:1�PF400:12 the floor was loaded with one point load. Before each test the measuring devices were zero-balanced. The load was increased monotonously up to a value which was estimated to be 50% or less of the failure load. The load-time relationship as well as the measured strains, crack widths and displacements are given graphically in App. C and some details in App. D. In test PF400:1 there was a sudden, uncontrolled increase in the load to 250 kN. In other tests the loading was under control all the time.

The displacements measured along the transverse line close to the loads were small, in all tests less than 1.1 mm. The settling of the supports was negligible, the highest value being of the order of 0.1 mm. The measured strains in the reinforcement of the tie beam were also small. Their highest value corresponded to the stress 22 MPa in the steel.

The ascending part of the load-deflection curves for the span (transducers 11�30) showed certain bilinearity in many cases, see Appendices C and D. This might have been due to cracking of the concrete, but then it would not have occurred during reloading (load on the next web).

The maximum change of crack width was of the order of 0.02 mm. This is much less than 0.3 mm which was the order of the crack width after precracking.

Figures 12�23 illustrate the deflection of the slab along a transverse line close to the load. In many cases there is a considerable discontinuity over the joints.

0.00.20.40.60.81.01.2

0 1.2 2.4 3.6 4.8

Distance from edge [mm]

Def

lect

ion

[mm

]

250 kN

Fig. 12. PF400:1. Deflection measured by transducers 11�30 at maximum load.

14

0.0

0.2

0.4

0.6

0.8

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

200 kN


0.00.10.20.30.40.50.60.7

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

150 kN

Fig. 14. PF400:3. Deflection measured by transducers 11�30 at maximum load. Transducer 26 (fifth from the right) out of action, see also App. C, Fig. 27.

0.00.10.20.30.40.50.6

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

150 kN


15

0.0

0.1

0.2

0.3

0.4

0.5

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

100 kN


-0.10.00.10.20.30.40.50.6

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

101 kN


0.00.10.20.30.40.50.60.7

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

100 kN


16

0.00.10.20.30.40.50.6

0 1.2 2.4 3.6 4.8Distance from edge [mm]

Def

lect

ion

[mm

]

150 kN


0.0

0.1

0.2

0.3

0.4

0.5

0 1.2 2.4 3.6 4.8Distance from edge [mm]

Def

lect

ion

[mm

]

150 kN


0.0

0.1

0.2

0.3

0.4

0.5

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

100 kN


17

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

100 kN


-0.10.00.10.20.30.40.50.60.7

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

101 kN


3.2 Failure tests

In test PF400:13 the floor was loaded with one point load. The failure mode was punching failure. To avoid this unintended failure mode in the remaining failure tests, the floor was loaded with two point loads in tests PF400:14 and PF400:15. In all three tests the load was increased monotonously until failure load. All measuring devices were zero-balanced before each test.

The load vs. time relationship as well as the measured strains, crack widths and displacements are given graphically in App. C. The failure loads are summarized in Fig. 24. The cracking patterns are illustrated in Figs 25�27 and in App. A, Figs 9�15, 17�26 and 31�36. See also Table 8 in which the observations made during the tests are

18

documented. The joint between the slab ends and cast in situ concrete remained uncracked, if some very thin shrinkage cracks are ignored, but there was a crack along the plastic sheet shown in Fig. 6 along the whole length of both supporting beams.

14

13

15

1

2

3

4

1000

14

Load in test PF400:15



Fmax = 518.2 kNShear failure of slabs 4 and 3, no longitudinal cracking

Fmax = 331.5 kN Longit. and transverse cracking in slab 3Punching failure at P = 324 kN

Fmax = 522.1 kNLongitudinal cracking in slab 2Shear failure in slabs 2 and 1

15

Fig. 24. Maximum imposed load Fmax and failure mode in failure tests.

13

1

2

3

4

Fmax = 331.5 kN Cracking in slab 3Punching failure at P = 324 kN

331

306 331305

321

304324

324

305

Fig. 25. Cracks observed during test PF400:13. The numbers refer to actuator force P when the crack became visible. The continuous and dashed lines represent cracks on the top and bottom surface, respectively.

19

14

1

2

3

4

14

Fmax = 522.1 kNLongitudinal cracking in slab 2Shear failure in slabs 2 and 1

505 505

505


15

1

2

3

4Fmax = 518.2 kNShear failure in slab 4

15

518 362

362266

299

518


As in tests with service load, the ascending part of the load-deflection curves for the span (transducers 11�30) was bilinear in many cases, see Appendices C and D. Furthermore, the

20

initial parts of the curves in tests PF400:13 and PF400:14 are close to those in tests PF400:1 and PF400:4. This is difficult to explain by cracking of the concrete but it may be attributable to the possible tilting of the supporting beams, which was not measured.

At maximum load, the displacements measured along the transverse line close to the loads were small, in all tests less than 3.5 mm. The settling of the supports was also negligible, the highest value being of the order of 0.3 mm. The measured strains in the reinforcement of the tie beam were also small. Their highest value corresponded to the stress 90 MPa in the steel in test PF400:15, but in other tests the stresses were below 12 MPa.

The maximum change of crack width was of the order of 0.08 mm. This is much less than 0.3 mm which was the order of the crack width before the test series was started.

0.0

0.5

1.0

1.5

2.0

2.5

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

251 kN300 kN331 kN

Fig. 28. PF400:13. Deflection measured by transducers 11�30 at different loads.

0.00.51.01.52.02.53.03.54.0

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

150 kN400 kN485 kN505 kN


21

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]100 kN250 kN400 kN517 kN


In Figs 31�33 the deflection measured in failure test is compared with the deflection measured in service load test. The deflections coincide rather well despite the permanent deformations and cracking which had taken place before the last two tests were started.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

251 kN, Fail250 kN, Ser

Fig. 31. Tests PF400:1 (Ser) and PF400:13 (Fail). Deflection measured by transducers 11�30 at load P ≈ 250 kN.

22

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]150 kN, Fail150 kN, Ser

Fig. 32. Tests PF400:4 (Ser) and PF400:14 (Fail). Deflection measured by transducers 11�30 at load P = 150 kN.

0.0

0.1

0.2

0.3

0.4

0.5

0 1.2 2.4 3.6 4.8


Def

lect

ion

[mm

]

100 kN, Fail100 kN, Ser

Fig. 33. Tests PF400:10 (Ser) and PF400:15 (Fail). Deflection measured by transducers 11�30 at load P = 100 kN.

23

24

4. Strength of concrete

The strength of the concrete was measured from 50 x 50 mmcores for the slab units and from 150 mm test cubes for the cast-in-situ concrete. The results are given in Tables 3�5. The cores were covered with plastic after drilling in such a way that they were still wet when tested. The test cubes were kept in the same temperature and relative humidity as the floor test specimen until testing.

Table 3. Strength and density of 50x50 mm cores drilled from slab units 2 and 3 and tested on 9th of October 2002.

Specimen Strength MPa

Density kg/m3

21 (slab 2) 75.5 2440 22 (slab 2) 67.0 2430 23 (slab 2) 71.5 2430 31 (slab 3) 79.0 2450 32 (slab 3) 79.0 2440 33 (slab 3) 77.0 2440

Mean x 74.8 2438 Standard deviation s 4.8 8

Characteristic strength fck,C50 = x�1.65s

66.8

Table 4. Strength and density of 150 mm test cubes cast from grouting in the longitudinal joints and tested on 3rd of October 2002.


Density kg/m3

S1 37.5 2250 S2 38.5 2240 S3 38.0 2250 S4 39.5 2270 S5 39.0 2260 S6 38.0 2250


Characteristic strength fck,K150 = x�1.65s

37.2

Table 5. Strength and density of 150 mm test cubes cast from grouting in the tie beams and tested on 3rd of October 2002.


Density kg/m3

P1 37.5 2260 P2 36.5 2260 P3 36.5 2240 P4 37.0 2270 P5 37.0 2230 P6 37.5 2260


Characteristic strength fck,K150 = x�1.65s

35.6

25

26

5. Analysis of results

It is assumed that the strength measured from 50 mm drilled cores gives directly the cubic strength measured from 150 mm cubes and that the cylinder strength is equal to 85% of the cubic strength. In this way, the lower characteristic cylinder strength fck,C150 (150 x 300 mm cylinders) given in Table 6 is obtained. From this, the mean tensile strength

⎟⎠⎞

⎜⎝⎛ ++=

MPaMPaf

f ckctm 10

81ln12,2 (1)

is obtained according to Eurocode 2 [2].

Table 6. Strength fc,C50 measured from 50 mm cores, corresponding cylinder strength fc,C150 and mean tensile strength fctm.

fc,C50

MPa

fc,C150

MPa

fctm

MPa

PF400 66.8 56.8 4.27

To give an impression about the shear resistance observed in tests PF400:13�PF400:15, a virtual load test PFR400 is analysed according to the product standard EN 1168 [1]. In this test a single slab element, identical to those in floor test and with similar support conditions, is loaded with a line load P at a distance of 1.0 m from slab end. It is assumed that the critical point is at the mid-depth of the cross-section and at a distance of 280 from the slab end (200 mm from the inner edge of the support). Since Eurocode 2 does not state clearly, which value can be regarded as the mean transfer length, two different values, 395 and 700 mm, are used for the transfer length. It is not clear, either, what would be the exact value for the loss of prestress. Therefore, calculations are made with two values: 5% and 10% of the initial prestressing force.

The cross-sectional characteristics of the slab are calculated from the nominal cross-section shown in Fig. 34 with the exception that the measured value 276 mm, see App. B, is used for bw, the sum of the web widths. In this way, the values given in Table 7 are obtained. In addition to the support reaction due to the imposed load Pu,pre, Vu,pre also includes the support reaction due to the dead weight of the slab.

4444

165

62

400114109

3664

7615

R120R120 R120R120

40 69 52 62

64

36

525262

228

762

194

55

83 95

1160

A B AB

36

Figure 34. Geometry used for calculating A, S and I.

Table 7. Virtual shear test PF400R. Distance from centroid of strands to the bottom fibre ep, distance from centroidal axis to bottom fibre e, sum of web widths bw, cross-sectional area A, second moment of area I and first moment of area above centroidal axis S, assumed transfer length lb, Assumed loss of prestress and predicted shear resistance Vu,pre (shear force at support).

ep

mm

e

mm

bw

mm

A

mm2

I

mm4

S

mm3

lb

mm

Loss

%

Pu,pre

kN

Vu,pre

kN

PF400R 35 200 276 210800 4.43.109 1.41.107 395 5 551 493 " " " " " " 395 10 495 488 " " " " " " 700 5 545 445 " " " " " " 700 10 491 441

Comparison of the calculated resistances Vu,pre indicates that the exact value of the loss is of little importance but the transfer length plays a major role. In Table 7 also the imposed load Pu,pre corresponding to the shear resistance is given. It is of the same order as the eccentric failure loads in tests PF400:14 and PF400:15.

In Table 8 the obtained resistances for different failure tests, virtual test PFR400 included, are compared.

27

28

Table 8. Failure load Fmax = Pmax + Peq (Pmax is the actuator force, Peq is the weight of loading equipment), its eccentricity e and description of response. Peq = 0.8 kN for tests PF400:14 and PF400:15. For other tests Peq = 0.3 kN.

Fmax kN

e mm

Observations

PF400:13

331.5 283 First cracks on the top of the floor at P = 305 kN. Load decreased with increasing displacements until P = 289 kN and started to increase again. At P = 331 kN there was a drop to 303 kN. The load could still be increased until at 324 kN a punching failure took place.

PF400:14

522.1 283 Shear or shear torsion failure in slabs 2 and 1 at P = 521 kN. With decreasing load at P = 505 kN cracks could be seen on the top surface.

PF400:15

518.2 283 At P = 266 kN a short longitudinal crack on the top of slab 4, see Fig. 27. At P = 517 kN shear failure in slab 4, but the load could still be kept at P = 340�360 kN for a longer period.

ST400E1M1)

264.8 283 Shear-torsion failure, test on a single slab unit supported on mortar bearing.

PFR400

491�551 0 Virtual test on a single slab unit. Shear tension failure. Fmax depends on assumed transfer length and loss of prestresss..

1) See report [3]

6. Discussion

The test specimens seemed to be typical of normal production. The strength of the concrete was high enough and the slippage of the strands was small in all elements. The loading and measuring equipment worked as intended with some insignificant exceptions.

The observed failure loads were higher than expected on the basis of the design practice presented in EN 1168 [1]. In the first failure test with one point load, a punching failure took place instead of the desired shear-torsion failure. In the remaining two failure tests with two point loads each, the failure mode was shear-torsion failure. In these two tests the local failure in the previous test(s) may have slightly reduced the observed resistance, but it is on the safe side to use the observed resistances as the real ones.

In view of the obtained high failure loads, the loads in most service load tests might have been higher. On the other hand, the response of the floor was so linear in the failure tests that increasing the maximum loads in the service load tests would not have affected the observed stiffness too much.

In most tests the load-deflection relationship looked bilinear in such a way that at the beginning the response was considerably stiffer than thereafter. It is not easy to explain this behaviour by clamping of the slab ends at the beginning and subsequent cracking because the bilinearity did not disappear after the first test. In fact, it was there still in the failure tests PF400:13�PF400:15 as shown in App. D in which the initial parts of the load-deflection curves are presented not only for the failure tests but also for the corresponding service load tests. Other possible explanations are hysteresis and tilting or horizontal sliding of the supporting beams along the supporting floor. The tilting or sliding cannot be confirmed by measurements because the horizontal displacements of the beams were not measured.

29

30

References

1. EN 1168. Precast concrete products � Hollow core slabs. 2005.

2. EN 1992-1-1. Eurocode 2: Design of concrete structures � Part 1: General rules and rules for buildings. 2004.

3. Pajari, M. Shear-torsion interaction tests on single hollow core slabs. Espoo 2004. VTT Research Notes 2275. 76 p. + app. 122 p. http://www.vtt.fi/inf/pdf/tiedotteet/2004/T2274.pdf

http://www.vtt.fi/inf/pdf/tiedotteet/2004/T2274.pdf

Appendix A: Photographs The numbers on the surface of the slabs refer to the actuator load. They tell the load at which the crack grew until the indicated position.

Fig. 1. Arrangements before jointing.

Fig. 2. Design of wedging equipment to create longitudinal cracks in the joints.

A1

Fig. 3. Crack in joint due to wedging.

Fig. 4. Crack in joint due to wedging.

A2

Fig. 5. Top surface of beam before grouting. Note the plastic sheet.

Fig. 6. Overview on test arrangements.

A3

Fig. 7. Horizontal transducers for measuring crack opening.

Fig. 8. Load at the edge of the floor.

A4

Fig. 9. PF400:13. Cracks after failure.


A5

Fig. 11. PF400:13. Cracks after failure on the top.

Fig. 12. PF400:13. Cracks in soffit of slab 3 after failure.

A6

Fig. 13. PF400:13. Cracks in soffit of slab 3 after failure.

Fig. 14. PF400:13. Longitudinal cracks in soffit of slab 3 after failure.

A7

Fig. 15. PF400:13. Cracks in tie beam at the loaded end after failure.

Fig. 16. PF400:14. Overview on arrangements.

A8

Fig. 17. PF400:14. View on loading details.

Fig. 18. PF400:14. Cracks in tie beam at the loaded end shown in red colour.

A9



A10


Fig. 22. PF400:14. Soffit after failure. Slab 1 in the front.

A11

Fig. 23. PF400:14. Soffit after failure. Slab 2 on the left, slab 1 on the right.

Fig. 24. PF400:14. Soffit after failure. Slab 2 on the left, slab 1 on the right.

A12

Fig. 25. PF400:14. Soffit after failure. Slab 1 in the front.

Fig. 26. PF400:14. PF400:14. Diagonal shear crack in slab 2 photographed after removal of slab 1.

A13

Fig. 27. PF400:15. Overview on arrangements.

Fig. 28. PF400:15. Loading arrangements.

A14

Fig. 29. PF400:15. Cracking pattern in Western tie beam after failure.

Fig. 30. PF400:15. Cracking after failure.

A15

Fig. 31. PF400:15. Soffit of slab 4 after failure.

Fig. 32. PF400:15. Soffit of slabs 4 and 3 (in the rear) after failure.

A16

Fig. 33. PF400:15. Soffit of slabs 4 (on the left) and 3 after failure.

Fig. 34. PF400:15. Top surface after failure.

A17

Fig. 35. PF400:15. Top surface after failure.

Fig. 36. PF400:15. Detail of top surface after failure.

A18

Appendix B: Measured slab cross-sections End 1 of slabs 1�4, see Figs 1�4, was the loaded end in floor test. The underlined figures give the measured spillage of the strands.

END 2 / EDGE 1 END 2 / EDGE 2

1156 (1165 at middepth)

38 39 39 38

400 226 21953 58 55 58 49

38 38 37 39

402

45 295

1196

1,1 2,1

36 40 35

1152

220

317

225

318320 318

398

0,6

35


Slab 1Lower strands : 11 d 12.5, prestress = 1000 MPa Length : 7081 mm

Mass : 3600 kg

340

1,4

36

1,5 1,3

36 37

2,1

35

1,2 1,0

35 40

2,1

35

315 574 619 595 848 895 873

1,3

38 44 39 38

400 225 21855 60 57 58 48

37 37 38 40

402

45 295

1195

1,0 1,6

37 42 35

1153

217

318

224

315321 320

400

0,7

37

342

1,2

37

1,4 0,9

37 37

1,7

36

1,6 1,2

36 40

1,6

36

316 575 620 595 849 895 875

1,1


Fig. 1. Slab 1.

B1



38 42 39 39

401 225 21955 59 56 58 49

37 38 37 40

402

45 295

1195

1,5 2,2

37 41 36

1154

218

318

225

315320 320

400

1.2

36



Mass : 3580 kg

341

1,4

36

2,0 1,7

37 37

2,7

37

1,6 1,4

35 39

1,5

35

316 575 620 596 849 896 875

1,3

37 40 39 39

400 225 21956 59 56 59 48

38 38 38 40

402

45 295

1195

1,0 1,3

38 42 37

1153

216

315

223

315321 316

398

0,9

38

341

1,2

38

1,5 1,4

38 39

2,1

38

1,6 1,2

37 41

1,8

37

316 574 620 596 849 896 873

1,2


Fig. 2. Slab 2.

B2



38 40 40 38

400 226 21748 60 55 58 55

39 37 36 38

400

43 300

1195

0,8 1,3

37 40 36

1151

222

313

227

317319 320

399

1.6

36



Mass : 3590 kg

347

1,5

36

1,2 2,0

36 36

1,9

35

1,4 1,5

35 42

1,7

36

321 576 622 600 855 900 880

1,2

38 40 40 38

400 226 21748 60 55 58 55

40 37 37 38

400

44 300

1195

0,7 1,1

40 41 36

1151

222

313

227

317319 320

399

1,1

40

348

1,5

37

1,2 1,4

38 38

2,1

38

0,8 0,8

38 43

1,0

38

323 577 623 600 855 902 880

0,9


Fig. 3. Slab 3.

B3



39 40 40 39

403 227 21955 58 55 60 49

40 38 38 38

403

44 295

1196

1,5 1,2

38 42 38

1152

218

318

223

318320 320

399

0,7

38



Mass : 3600 kg

340

0,9

38

1,6 1,5

38 40

1,6

38

1,4 1,0

38 40

1,5

37

311 573 619 595 848 894 873

0,8

35 38 39 40

401 225 21855 59 56 60 50

39 39 40 40

403

43 292

1196

1,1 1,4

37 40 35

1153

218

317

224

315320 318

400

0,9

37

339

1,1

37

1,6 1,3

37 38

1,5

36

1,4 1,4

35 40

2,2

35

313 573 618 595 849 896 873

1,1


Fig. 4. Slab 4.

B4

Appendix C: Measured forces, strains and displacements

0

50

100

150

200

250

300

0 10 20 30 40 50 60Time [min]

Load

[kN

]

Fig. 1. PF400:1. Load-time relationship.

0

50

100

150

200

250

300

-0.020 -0.010 0.000 0.010

∆(Crack width) [mm]

Load

[kN

]

123456

Fig. 2. PF400:1. Change of crack width measured by transducers 1�6.

C1

0

50

100

150

200

250

300

-20 -10 0 10 20 30 40 50 60

Strain [10-6]

Load

[kN

]

78910

Fig. 3. PF400:1. Strain in tie reinforcement measured by transducers 7�9.

0

50

100

150

200

250

300

-0.1 0.0 0.1 0.2 0.3 0.4 0.5

Displacement [mm]

Load

[kN

]

1112131415

Fig. 4. PF400:1. Vertical displacement measured by transducers 11�15.

0

50

100

150

200

250

300

-0.2 0.0 0.2 0.4 0.6 0.8

Displacement [mm]

Load

[kN

]

1617181920


C2

0

50

100

150

200

250

300

-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2

Displacement [mm]

Load

[kN

]

2122232425


0

50

100

150

200

250

300

-0.2 0.0 0.2 0.4 0.6 0.8

Displacement [mm]

Load

[kN

]

2627282930


0

50

100

150

200

250

300

-0.02 0.00 0.02 0.04 0.06 0.08 0.10

Displacement [mm]

Load

[kN

]

313233343536


C3

0

50

100

150

200

250

300

-0.02 0.00 0.02 0.04 0.06 0.08 0.10

Displacement [mm]

Load

[kN

]

373839404142


0

50

100

150

200

250

300

-0.02 0.00 0.02 0.04

Displacement [mm]

Load

[kN

]

4344454647


0

50

100

150

200

250

0 10 20 30 40Time [min]

Load

[kN

]


C4

020406080

100120140160180200

-0.03 -0.02 -0.01 0.00 0.01


Load

[kN

] 123456


0

50

100

150

200

250

-10 0 10 20 30 40

Strain [10-6]

Load

[kN

]

78910


0

50

100

150

200

250

-0.1 0.0 0.1 0.2 0.3 0.4 0.5

Displacement [mm]

Load

[kN

]

1112131415


C5

0

50

100

150

200

250

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Displacement [mm]

Load

[kN

]

1617181920


0

50

100

150

200

250

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6

Displacement [mm]

Load

[kN

]

2122232425


0

50

100

150

200

250

-0.1 0.0 0.1 0.2 0.3

Displacement [mm]

Load

[kN

] 2627282930


C6

0

50

100

150

200

250

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

]

313233343536


0

50

100

150

200

250

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

] 373839404142


0

50

100

150

200

250

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

] 4344454647


C7

020406080

100120140160

0 10 20 30 40Time [min]

Load

[kN

]


020406080

100120140160

-0.015 -0.010 -0.005 0.000 0.005


Load

[kN

] 123456


020406080

100120140160

-20 0 20 40 60 80 100 120

Strain [10-6]

Load

[kN

]

78910


C8

0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3

Displacement [mm]

Load

[kN

]

1112131415


0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Displacement [mm]

Load

[kN

]

1617181920


0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3

Displacement [mm]

Load

[kN

] 2122232425


C9

C10

0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Displacement [mm]

Load

[kN

] 2627282930

Fig. 27. PF400:3. Vertical displacement measured by transducers 26�30. Transducer 26 out of action.

0

20

40

60

80

100

120

140

160

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

]

313233343536


0

20

40

60

80

100

120

140

160

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

]

373839404142


0

20

40

60

80

100

120

140

160

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

] 4344454647


020406080

100120140160

0 10 20Time [min]

Load

[kN

]

30


020406080

100120140160

-0.015 -0.010 -0.005 0.000 0.005


Load

[kN

]

123456


C11

020406080

100120140160

-4 -2 0 2 4 6 8 10 12

Strain [10-6]

Load

[kN

]

78910


0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3 0.4 0.5

Displacement [mm]

Load

[kN

]

1112131415


0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3 0.4 0.5

Displacement [mm]

Load

[kN

]

1617181920


C12

0

20

40

60

80

100

120

140

160

-0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30

Displacement [mm]

Load

[kN

]

2122232425


0

20

40

60

80

100

120

140

160

-0.05 0.00 0.05 0.10 0.15

Displacement [mm]

Load

[kN

]

2627282930


020406080

100120140160180

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

]

313233343536


C13

020406080

100120140160180

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

]

373839404142


020406080

100120140160180

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

] 4344454647


0

20

40

60

80

100

120

0 10 20 3Time [min]

Load

[kN

]

0


C14

0

20

40

60

80

100

120

-0.010 -0.005 0.000 0.005


Load

[kN

]

123456


0

20

40

60

80

100

120

-3 -2 -1 0 1 2 3 4 5 6

Strain [10-6]

Load

[kN

]

78910


0

20

40

60

80

100

120

-0.20 0.00 0.20 0.40 0.60 0.80

Displacement [mm]

Load

[kN

] 1112131415


C15

0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30

Displacement [mm]

Load

[kN

]

1617181920


0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

2122232425


0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

2627282930


C16

0

20

40

60

80

100

120

-0.02 0.00 0.02 0.04

Displacement [mm]

Load

[kN

] 313233343536


0

20

40

60

80

100

120

-0.02 0.00 0.02 0.04

Displacement [mm]

Load

[kN

]

373839404142


0

20

40

60

80

100

120

-0.02 0.00 0.02 0.04

Displacement [mm]

Load

[kN

] 4344454647


C17

0

20

40

60

80

100

120

0 10 20Time [min]

Load

[kN

]

30


0

20

40

60

80

100

120

-0.005 0.000 0.005


Load

[kN

] 123456


0

20

40

60

80

100

120

-4 -3 -2 -1 0 1 2 3 4 5

Strain [10-6]

Load

[kN

]

78910


C18

0

20

40

60

80

100

120

-0.1 0.0 0.1 0.2 0.3 0.4 0.5

Displacement [mm]

Load

[kN

]

1112131415


0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30

Displacement [mm]

Load

[kN

]

1617181920


0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

2122232425


C19

0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

2627282930


0

20

40

60

80

100

120

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

] 313233343536


0

20

40

60

80

100

120

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

] 373839404142


C20

0

20

40

60

80

100

120

-0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

]

4344454647


0

20

40

60

80

100

120

0 10 20 3Time [min]

Load

[kN

]

0


0

20

40

60

80

100

120

-0.005 0.000 0.005 0.010


Load

[kN

] 123456


C21

0

20

40

60

80

100

120

-5 -4 -3 -2 -1 0 1 2 3 4 5

Strain [10-6]

Load

[kN

]

78910


0

20

40

60

80

100

120

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

Displacement [mm]

Load

[kN

]

1112131415


0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30

Displacement [mm]

Load

[kN

]

1617181920


C22

0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

2122232425


0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

2627282930


0

20

40

60

80

100

120

-0.04 -0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

]

313233343536


C23

0

20

40

60

80

100

120

-0.04 -0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

]

373839404142


0

20

40

60

80

100

120

-0.04 -0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

]

4344454647


020406080

100120140160

0 10 20 3Time [min]

Load

[kN

]

0


C24

020406080

100120140160

-0.015 -0.010 -0.005 0.000 0.005


Load

[kN

]

123456


020406080

100120140160180

-5 0 5 10 15 20

Strain [10-6]

Load

[kN

]

78910


0

20

40

60

80

100

120

140

160

-0.05 0.00 0.05 0.10 0.15 0.20

Displacement [mm]

Load

[kN

]

1112131415


C25

0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3

Displacement [mm]

Load

[kN

]

1617181920


0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6

Displacement [mm]

Load

[kN

]

2122232425


0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3 0.4

Displacement [mm]

Load

[kN

]

2627282930


C26

0

20

40

60

80

100

120

140

160

-0.02 0.00 0.02 0.04

Displacement [mm]

Load

[kN

] 313233343536


0

20

40

60

80

100

120

140

160

-0.02 0.00 0.02 0.04

Displacement [mm]

Load

[kN

]

373839404142


0

20

40

60

80

100

120

140

160

-0.02 0.00 0.02 0.04

Displacement [mm]

Load

[kN

]

4344454647


C27

020406080

100120140160

0 10 20 3Time [min]

Load

[kN

]

0


020406080

100120140160

-0.015 -0.010 -0.005 0.000 0.005


Load

[kN

]

123456


020406080

100120140160180

-5 0 5 10 15 20

Strain [10-6]

Load

[kN

]

78910


C28

0

20

40

60

80

100

120

140

160

-0.05 0.00 0.05 0.10 0.15

Displacement [mm]

Load

[kN

]

1112131415


0

20

40

60

80

100

120

140

160

-0.05 0.00 0.05 0.10 0.15 0.20 0.25

Displacement [mm]

Load

[kN

]

1617181920


0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6

Displacement [mm]

Load

[kN

]

2122232425


C29

0

20

40

60

80

100

120

140

160

-0.1 0.0 0.1 0.2 0.3 0.4 0.5

Displacement [mm]

Load

[kN

]

2627282930


0

20

40

60

80

100

120

140

160

-0.02 0.00 0.02 0.04

Displacement [mm]

Load

[kN

] 313233343536


0

20

40

60

80

100

120

140

160

-0.02 0.00 0.02 0.04

Displacement [mm]

Load

[kN

]

373839404142


C30

0

20

40

60

80

100

120

140

160

-0.02 0.00 0.02 0.04

Displacement [mm]

Load

[kN

]

4344454647


0

20

40

60

80

100

120

0 10 20 3

Time [min]

Load

[kN

]

0


0

20

40

60

80

100

120

-0.005 0.000 0.005∆(Crack width) [mm]

Load

[kN

] 123456


C31

0

20

40

60

80

100

120

-20 0 20 40 60 80

Strain [10-6]

Load

[kN

]

78910


0

20

40

60

80

100

120

-0.10 -0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

1112131415


0

20

40

60

80

100

120

-0.10 -0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

] 1617181920


C32

0

20

40

60

80

100

120

-0.1 0.0 0.1 0.2 0.3 0.4 0.5

Displacement [mm]

Load

[kN

]

2122232425


0

20

40

60

80

100

120

-0.1 0.0 0.1 0.2 0.3 0.4 0.5

Displacement [mm]

Load

[kN

]

2627282930


0

20

40

60

80

100

120

-0.04 -0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

]

313233343536


C33

0

20

40

60

80

100

120

-0.04 -0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

] 373839404142


0

20

40

60

80

100

120

-0.04 -0.02 0.00 0.02 0.04 0.06

Displacement [mm]

Load

[kN

] 4344454647


0

20

40

60

80

100

120

0 10 20 3

Time [min]

Load

[kN

]

0


C34

0

20

40

60

80

100

120

-0.005 0.000 0.005 0.010∆(Crack width) [mm]

Load

[kN

] 123456


0

20

40

60

80

100

120

-60 -40 -20 0 20 40 60 80

Strain [10-6]

Load

[kN

]

78910


0

20

40

60

80

100

120

-0.10 -0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

] 1112131415


C35

0

20

40

60

80

100

120

-0.10 -0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

] 1617181920


0

20

40

60

80

100

120

-0.1 0.0 0.1 0.2 0.3

Displacement [mm]

Load

[kN

] 2122232425


0

20

40

60

80

100

120

-0.2 0.0 0.2 0.4 0.6

Displacement [mm]

Load

[kN

]

2627282930


C36

0

20

40

60

80

100

120

-0.04 -0.02 0.00 0.02

Displacement [mm]

Load

[kN

] 313233343536


0

20

40

60

80

100

120

-0.04

-0.02

0.00 0.02 0.04 0.06 0.08 0.10

Displacement [mm]

Load

[kN

]

373839404142


0

20

40

60

80

100

120

-0.04 -0.02 0.00 0.02

Displacement [mm]

Load

[kN

] 4344454647


C37

0

20

40

60

80

100

120

0 10 20 3

Time [min]

Load

[kN

]

0


0

20

40

60

80

100

120

-0.005 0.000 0.005 0.010 0.015


Load

[kN

]

123456


0

20

40

60

80

100

120

-60 -50 -40 -30 -20 -10 0 10

Strain [10-6]

Load

[kN

]

78910


C38

0

20

40

60

80

100

120

-0.10 -0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

1112131415


0

20

40

60

80

100

120

-0.10 -0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

1617181920


0

20

40

60

80

100

120

-0.1 0.0 0.1 0.2 0.3

Displacement [mm]

Load

[kN

]

2122232425


C39

0

20

40

60

80

100

120

-0.2 0.0 0.2 0.4 0.6 0.8

Displacement [mm]

Load

[kN

]

2627282930


0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10 0.15

Displacement [mm]

Load

[kN

]

313233343536


0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10 0.15

Displacement [mm]

Load

[kN

]

373839404142


C40

0

20

40

60

80

100

120

-0.05 0.00 0.05 0.10 0.15

Displacement [mm]

Load

[kN

] 4344454647


0

50

100

150

200

250

300

350

0 20 40 60 80 100 120Time [min]

Load

[kN

]


0

50

100

150

200

250

300

350

-0.15 -0.10 -0.05 0.00 0.05∆(Crack width) [mm]

Load

[kN

] 123456


C41

0

50

100

150

200

250

300

350

-200 -150 -100 -50 0 50 100

Strain [10-6]

Load

[kN

]

78910


0

50

100

150

200

250

300

350

-0.2 0.0 0.2 0.4 0.6 0.8

Displacement [mm]

Load

[kN

]

1112131415


0

50

100

150

200

250

300

350

-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2

Displacement [mm]

Load

[kN

]

1617181920


C42

0

50

100

150

200

250

300

350

-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Displacement [mm]

Load

[kN

]

2122232425


0

50

100

150

200

250

300

350

-0.2 0.0 0.2 0.4 0.6 0.8

Displacement [mm]

Load

[kN

]

2627282930


0

50

100

150

200

250

300

350

-0.05 0.00 0.05 0.10 0.15

Displacement [mm]

Load

[kN

] 313233343536


C43

0

50

100

150

200

250

300

350

-0.05 0.00 0.05 0.10 0.15

Displacement [mm]

Load

[kN

]

373839404142


0

50

100

150

200

250

300

350

-0.05 0.00 0.05 0.10 0.15

Displacement [mm]

Load

[kN

] 4344454647


0

100

200

300

400

500

600

0 10 20 30 40 50 60 70 80 90Time [min]

Load

[kN

]


C44

0

100

200

300

400

500

600

-0.20 -0.15 -0.10 -0.05 0.00 0.05∆(Crack width) [mm]

Load

[kN

]

123456


0

100

200

300

400

500

600

-10 0 10 20 30

Strain [10-6]

Load

[kN

]

8910

Fig. 133. PF400:14. Strain in tie reinforcement measured by transducers 8�9. (No. 7 out of action).

0

100

200

300

400

500

600

-1 0 1 2 3 4 5 6

Displacement [mm]

Load

[kN

]

1112131415


C45

0

100

200

300

400

500

600

-1 0 1 2 3 4 5 6

Displacement [mm]

Load

[kN

]

1617181920


0

100

200

300

400

500

600

-0.5 0.0 0.5 1.0 1.5 2.0

Displacement [mm]

Load

[kN

]

2122232425


0

100

200

300

400

500

600

-0.2 0.0 0.2 0.4 0.6 0.8

Displacement [mm]

Load

[kN

]

2627282930


C46

0

100

200

300

400

500

600

-0.10 0.00 0.10 0.20 0.30

Displacement [mm]

Load

[kN

] 313233343536


0

100

200

300

400

500

600

-0.20 -0.10 0.00 0.10 0.20Displacement [mm]

Load

[kN

] 373839404142


0

100

200

300

400

500

600

-0.20 -0.10 0.00 0.10 0.20

Displacement [mm]

Load

[kN

] 4344454647


C47

0

100

200

300

400

500

600

0 10 20 30 40 50 60 70 80 90Time [min]

Load

[kN

]


0

100

200

300

400

500

600

-0.10 -0.05 0.00 0.05 0.10∆(Crack width) [mm]

Load

[kN

] 123456


0

100

200

300

400

500

600

-200 0 200 400 600

Strain [10-6]

Load

[kN

]

8910

Fig. 143. PF400:15. Strain in tie reinforcement measured by transducers 8�9. (No. 7 out of action).

C48

0

100

200

300

400

500

600

-0.2 0.0 0.2 0.4 0.6 0.8

Displacement [mm]

Load

[kN

]

1112131415


0

100

200

300

400

500

600

-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2

Displacement [mm]

Load

[kN

]

1617181920


0

100

200

300

400

500

600

-1 0 1 2 3 4 5 6

Displacement [mm]

Load

[kN

]

2122232425


C49

0

100

200

300

400

500

600

-1 0 1 2 3 4 5 6 7 8

Displacement [mm]

Load

[kN

]

2627282930


0

100

200

300

400

500

600

-0.20 -0.10 0.00 0.10 0.20

Displacement [mm]

Load

[kN

] 313233343536


0

100

200

300

400

500

600

-0.10 0.00 0.10 0.20 0.30

Displacement [mm]

Load

[kN

]

373839404142


C50

0

100

200

300

400

500

600

-0.30 -0.20 -0.10 0.00 0.10

Displacement [mm]

Load

[kN

]4344454647


C51

Appendix D: Initial part of load-deflection curves

0

20

40

60

80

100

-0.1 0.0 0.1 0.2

Displacement [mm]

Load

[kN

]

1112131415


0

20

40

60

80

100

-0.1 0.0 0.1 0.2 0.3

Displacement [mm]

Load

[kN

]

1617181920


D1

0

20

40

60

80

100

-0.2 0.0 0.2 0.4

Displacement [mm]

Load

[kN

]

2122232425


0

20

40

60

80

100

-0.1 0.0 0.1 0.2

Displacement [mm]

Load

[kN

]

2627282930


0

20

40

60

80

100

-0.1 0.0 0.1 0.2 0.3

Displacement [mm]

Load

[kN

]

1112131415


D2

0

20

40

60

80

100

-0.1 0.0 0.1 0.2 0.3

Displacement [mm]

Load

[kN

]

1617181920


0

20

40

60

80

100

-0.05 0.00 0.05 0.10 0.15

Displacement [mm]

Load

[kN

]

2122232425


0

20

40

60

80

100

-0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

2627282930


D3

0

20

40

60

80

100

120

-0.10 -0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

]

1112131415


0

20

40

60

80

100

120

-0.10 -0.05 0.00 0.05 0.10

Displacement [mm]

Load

[kN

] 1617181920


0

20

40

60

80

100

120

-0.1 0.0 0.1 0.2 0.3 0.4 0.5

Displacement [mm]

Load

[kN

]

2122232425


D4

0

20

40

60

80

100

120

-0.1 0.0 0.1 0.2 0.3 0.4 0.5

Displacement [mm]

Load

[kN

]

2627282930


0

50

100

150

200

-0.2 0.0 0.2 0.4

Displacement [mm]

Load

[kN

]

1112131415


0

50

100

150

200

-0.2 0.0 0.2 0.4 0.6

Displacement [mm]

Load

[kN

]

1617181920


D5

0

50

100

150

200

-0.5 0.0 0.5 1.0

Displacement [mm]

Load

[kN

]

2122232425


0

50

100

150

200

-0.2 0.0 0.2 0.4

Displacement [mm]

Load

[kN

]

2627282930


0

50

100

150

200

250

300

-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2

Displacement [mm]

Load

[kN

]

1112131415


D6

0

50

100

150

200

250

300

-0.5 0.0 0.5 1.0 1.5

Displacement [mm]

Load

[kN

]

1617181920


0

50

100

150

200

250

300

-0.5 0.0 0.5 1.0

Displacement [mm]

Load

[kN

]

2122232425


0

50

100

150

200

250

300

-0.2 0.0 0.2 0.4

Displacement [mm]

Load

[kN

]

2627282930


D7

0

50

100

150

200

250

300

-0.2 0.0 0.2 0.4

Displacement [mm]

Load

[kN

]

1112131415


0

50

100

150

200

250

300

-0.2 0.0 0.2 0.4 0.6

Displacement [mm]

Load

[kN

]

1617181920


0

50

100

150

200

250

300

-0.5 0.0 0.5 1.0 1.5

Displacement [mm]

Load

[kN

]

2122232425


D8

0

50

100

150

200

250

300

-1 0 1 2

Displacement [mm]

Load

[kN

]

2627282930


D9

Published by

Series title, number and report code of publication

VTT Research Notes 2274VTT�TIED�2274

Author(s) Pajari, Matti Title Shear-torsion tests on 400 mm hollow core floor Abstract Fifteen load tests on a floor comprising four prestressed hollow core slabs were carried out to clarify the interaction of shear and torsion. The slabs were 400 mm in depth, 1.2 m in width and 7 m in length. The ends of the slabs were simply supported on concrete beams. The loads in each test comprised one or two concentrated loads close to the support.

In twelve tests the loads were limited to a typical service load. In these tests the behaviour of the floor was relatively linear and no sign of failure could be observed. In three tests the floor failed locally. The observed failure loads were 25�97% higher than in a reference test on a single slab unit with identical support conditions. In the first failure test with one point load the failure mode was punching. In other two tests with two point loads, as well as in the reference test with one point load, the failure was a typical shear-torsion failure.

As a subtask of HOLCOTORS project, the test results have been used by Chalmers University of Technology for calibration of computerized calculation methods they have developed. This work is published elsewhere. Therefore, the present design practice has not been evaluated here in view of the obtained results.

Keywords shear tests, torsion tests, hollow core slabs, floors, testing, test specimens, load testing, failure loads, load distribution, concrete, precast, prestressed, structure

Activity unit VTT Building and Transport, Kemistintie 3, P.O.Box 1805, FIN�02044 VTT, Finland

ISBN Project number 951�38�6518�5 (URL: http://www.vtt.fi/inf/pdf/) R2SU00137

Date Language Pages Price December 2005 English 30 p. + app. 82 p. -

Name of project Commissioned by Holcotors EU, Concrete industry, VTT

Series title and ISSN Published by VTT Tiedotteita � Research Notes 1455�0865 (URL: http://www.vtt.fi/inf/pdf/)

VTT Information Service P.O.Box 2000, FIN�02044 VTT, Finland Phone internat. +358 9 456 4404 Fax +358 9 456 4374



VTT RESEA

RCH N

OTES 2274Shear-torsion tests on 400 m

m hollow

core floor

ISBN 951–38–6518–5 (URL: http://www.vtt.fi/inf/pdf/)ISSN 1455–0865 (URL: http://www.vtt.fi/inf/pdf/)

ESPOO 2004 VTT RESEARCH NOTES 2274

Fifteen load tests on a floor comprising four prestressed hollow core slabswere carried out to clarify the interaction of shear and torsion. The slabswere 400 mm in depth and 7 m in length. The ends of the slabs were simplysupported on concrete beams. The loads in each test comprised one or twoconcentrated loads close to the support.

In twelve tests the loads were limited to a typical service load. Inthese tests the behaviour of the floor was relatively linear. In three teststhe floor was loaded to failure. The observed failure loads were 25–97%higher than in a reference test on a single slab unit. In the first failuretest with one point load, the failure mode was punching. In other twotests with two point loads, as well as in the reference test with one pointload, the failure was a typical shear – torsion failure.

Matti Pajari

Shear-torsion tests on 400 mmhollow core floor

1211

12

3 45

67

89

10

VTT TIETOPALVELU VTT INFORMATIONSTJÄNST VTT INFORMATION SERVICEPL 2000 PB 2000 P.O.Box 2000

02044 VTT 02044 VTT FIN–02044 VTT, FinlandPuh. 020 722 4404 Tel. 020 722 4404 Phone internat. + 358 20 722 4404Faksi 020 722 4374 Fax 020 722 4374 Fax + 358 20 722 4374



Shear-torsion tests on 400 mm hollow core floor

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Transcript of Shear-torsion tests on 400 mm hollow core floor