LICENTIATE THESIS - Luleå tekniska universitet

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the level of the applied load. The vertical crack at the fastener and downwards probably comes from track forces, i.e. the presence of this crack depends on where it has been lying in the track (curves etc) where it has been exposed to high forces. It was also possible to see a variation of the load carrying capacity of the fastener for the yellow sleepers. But the results show that there is nothing to gain by dividing the yellow sleepers into groups since they manage approximately the same loads. The material properties of the concrete in the tested sleepers were high. The mean value for 16 compression tests was 100.7 MPa and the mean value for 13 tensile tests was 3.9 MPa. The sleepers produced with inferior methods are now inspected annually in order to see at what rate the cracking is progressing. The big question is now how fast a green or yellow sleeper turns into a red one, i.e. how fast is the formation of ettringite? Probably weather conditions have an important role. If a sleeper will be exposed to cyclic frost erosion the process ought to accelerate considerably. An indication of that the weather conditions may play an important role has been discovered on one sleeper. The midsection of this sleeper had been covered with equipment for the signalling system a so-called “Balis” and this part seemed to be in better conditions (no visible cracks) in comparison with the ends where the crack system had developed quite a bit. The next steps in the project will be to test the fatigue capacity of a yellow/red sleeper and to perform some more tests of the bending capacity in the midsection and rail section with yellow/red sleepers. It might also be tests where a rail is mounted on the sleeper and the load is applied on this instead of directly in the fastener and see if this changes the result. Acknowledgements The investigation was carried out on behalf of the Swedish National Rail Administration. Björn Paulsson and Paul Nilsson together with their staff have provided much information and help. TESTLAB (the test laboratory at Luleå University of Technology) has performed the tests in collaboration with the first two authors. Notation fcc fct Fu concrete compression strength concrete tensile strength ultimate force at failure M f, mid moment bearing capacity at the midsection of the sleeper including 1.75 safety factor against failure - 22 -
M f,rail moment bearing capacity at the rail section of the sleeper including 1.75 safety factor against failure REFERENCES Andersson, Evert and Berg, Mats. (1999). Järnvägssystem och spårfordon. Del 1: järnvägssystem (Rail system and rail vehicles. In Swedish). Järnvägsgruppen KTH. Centrum för forskning och utbildning i järnvägsteknik. Stockholm. 1999. KTH Högskoletryckeriet. BVF 522.32 (1995): Tekniska bestämmelser, sliprar av betong (Technical regulations, concrete sleepers. In Swedish). 6+2 sid. Collepardi, Mario (1999): Damage by delayed ettringite formation. Concrete International, American Concrete Institute, Farmington Hills, MI, USA,V.21, No1. 1999, pp. 69-74. Elfgren, Lennart, Editor (1989): Fracture mechanics of concrete structures. From theory to applications. Chapman & Hall, London, London 1989, 407 pp. ISBN 0 412 30680 8. Elfgren, Lennart, Editor (1998): Round Robin Analysis and Tests of Anchor Bolts in Concrete Structures. RILEM Technical Committee 90-FMA Fracture Mechanics of Concrete - Applications. Research Report 1998:14, Division of Structural Engineering, Luleå University of Technology, 54 + 371 pp Eligehausen, Rolf, Editor (1994): Fastenings to concrete and masonry structures. State of the art report. Comité Euro-International du Béton, CEB Bulletin 216. Thomas Telford, London 1994, 249 pp. ISBN 0 7277 1937 8. Gylltoft, Kent (1978): Utmattningsprov av betongsliprar- Utveckling av provnings- och mätmetodik vid experimentell utmattningsforskning (Fatigue of concrete sleepers. Test methods. In Swedish). Byggforskningen, Rapport R103:1978, Stockholm 1978, ISBN 91-540- 2939-2, 92 sid. Gylltoft, Kent and Elfgren, Lennart (1977): Utmattningshållfasthet för anläggningskonstruktioner (Fatigue of civil engineering structures. In Swedish). Byggforskningen, Rapport R68:1977, Stockholm 1987, ISBN 91-540-2750-0, 160 sid. Hime, William (1996): Delayed ettringite formation- A concern for precast concrete?. PCI Journal, Precast/Prestressed Concrete Institute, Chicago, IL, USA,V.41, No4. 1996, pp. 26- 30. Noghabai Keivan (1998): Effect of Tension Softening on the Performance of Concrete Structures. Experimental, Analytical and Computational Studies. Doctoral thesis 1998:21, Div of Structural Engineering, Luleå University of Technology, Luleå, Sweden, 1998, 147 pp. Ohlsson, Ulf (1995): Fracture mechanics analysis of concrete structures. Division of Structural Engineering, Luleå University of Technology, Doctoral Thesis 1995:179D, Luleå 1995, 94 pp. (ISSN 0348-8373). - 23 -
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LICENTIATE THESIS Evaluation of Con
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Preface This licentiate thesis pres
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Evaluation of Concrete Structures I
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Evaluation of Concrete Structures I
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Evaluation of Concrete Structures 4
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A. Simplified check A1. In-situ ins
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Evaluation of Concrete Structures G
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Lok-Strength & Capo-Strength F [kN]
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Evaluation of Concrete Structures a
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Evaluation of Concrete Structures t
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Evaluation of Concrete Structures d
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Evaluation of Concrete Structures T
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Evaluation of Concrete Structures -
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6 Outlook Evaluation of Concrete St
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Page 47: Paper A CONCRETE STRENGTH DEVELOPME
Page 50 and 51: determine the in-place strength of
Page 52 and 53: strength could be the fact for all
Page 54 and 55: German Petersen & Poulsen (1993), s
Page 56 and 57: Rebound test (Schmidt-hammer) The r
Page 58 and 59: expected (about 8 MPa). But for the
Page 60 and 61: Figure 8 shows the location where t
Page 62 and 63: Tensile strength [MPa] 6.0 5.0 4.0
Page 64 and 65: Table 4 Mean value and standard dev
Page 66 and 67: Lok-Strength & Capo-Strength F [kN]
Page 68 and 69: fcc fct concrete compression streng
Page 70 and 71: The values that have been used are:
Page 73 and 74: LOAD CARRYING CAPACITY OF CRACKED C
Page 75 and 76: Figure 1 Principal drawing of teste
Page 77 and 78: Class 3. OK / Green: No visible cra
Page 79 and 80: 0.5 1.0 +15 kNm 0.5 0.5 1.0 0.5 -11
Page 81 and 82: Horizontal force [kN] 100 80 60 40
Page 83 and 84: TEST SET-UP AND RESULTS Bending cap
Page 85 and 86: The displacement was measured by fo
Page 87 and 88: Figure 18 Failure of sleeper no. 10
Page 89 and 90: Sleeper No. 17 looks more like the
Page 91 and 92: c2 75 á 100 where ψ ′ c = = = 0
Page 93: The obtained stress σ t = 4.45 MPa
Page 97: Paper C CONCRETE FATIGUE CAPACITY.
Page 100 and 101: FATIGUE OF CONCRETE A common way to
Page 102 and 103: notch is deep enough that is). When
Page 104 and 105: Figure 5 Test set-up uniaxial tensi
Page 106 and 107: Table 1 A summary of all uniaxial t
Page 108 and 109: Strain [‰] 0.8 0.6 0.4 0.2 0 Phas
Page 110 and 111: 11) the start of phase 3 takes plac
Page 112 and 113: ACKNOWLEDGEMENTS The study has been
Page 114 and 115: APPENDIX A Evaluated data from the
Page 116 and 117: C = dε / dN [× 10 −6 ] 100 10 1
Page 118 and 119: Test series A: S min = σ min / f c
Page 121: Paper D SHEAR FATIGUE CAPACITY - A
Page 124 and 125: 1 Introduction The codes that have
Page 126 and 127: Dead Loads: Slab: 0.320 m á 24 kN/
Page 128 and 129: the equations to calculate the desi
Page 130 and 131: where ηγm is 1.5 for concrete (co
Page 132 and 133: different besides the strength clas
Page 134 and 135: Table 4.2 Fatigue strength. Number
Page 136 and 137: The shear force capacity, V Rd1, fo
Page 138 and 139: σ cd,min,equ lower stresses of the
Page 140 and 141: 6.2 Strength values at fatigue load
Page 142 and 143: 6.3 Strength values at fatigue load
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1 − 0.7166 14 ⋅ = 4.71 < 6 ⇒T
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The “new” equation for the desi
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Appendix A. Concrete Codes Excerpt
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DOCTORAL AND LICENTIATE THESES Divi
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