LICENTIATE THESIS - Luleå tekniska universitet

More documents

Recommendations

Info

Evaluation of Concrete Structures - The expression to calculate the design fatigue strength. - The Swedish Code gives an approximate value of the number of cycles before failure (the value is taken from a graph). The reason why EC2-draft (1999) is much more conservative than the EC2-2 (1995)/EC2-1 (1991) depends on how the shear strength is calculated. The new equation in EC2-draft (1999) to calculate the design value for the shear strength gives a lower value compared to the EC2-1 (1991). The “new” equation for the design shear strength in EC2-draft (1999) is taken from MC 90 (1993), section 6.4.2.3: “Shear in cracked zones without shear reinforcement”. It has the following formula: ( ρ ) 1/ 3 Rd1 ck red V = 0.12 ⋅k100 ⋅ ⋅ f ⋅b ⋅ d (Eq. 6.4-8 in MC 90 (1993)) The reason to this change is that there has been some uncertainty when it comes to high strength ordinary concrete and to be on the safe side a reduction of the design shear strength has been made. This reduction has led to, for example that the difference in fatigue shear strength is as much as 35% for C80 (VRd1-fat and VRd,ct-fat), see Table 5.2and Figure 5.4. Table 5.2 Design value for the shear strength according to EC2-1 (1991) and EC2-draft (1999). A) Strength Class C30 C40 C50 C60 C80 EC2-1 (1991) / EC2- 2 (1995) VRd1 = 189.0 236.2 274.0 292.9 321.2 kN VRd1-fat = 189.0 236.2 274.0 292.9 321.2 kN EC2-draft (1999) VRd.ct = 176.5 194.2 209.2 222.4 244.7 kN VRd,ct-fat = 164.3 178.0 188.7 197.1 209.0 kN A) Strength classes according to EC2-draft (1999). Shear force capcity, V Rd [kN] 350 300 250 200 150 C30 C40 C50 C60 C80 Concrete Class - 26 - EC2-1 (1991) / EC2-2 (1995) V Rd,ct V Rd,ct-fat EC2-draft (1999) EC2-draft (1999) Figure 5.4 Design value for the shear strength according to EC2-1 (1991) and EC2-draft (1999).
Evaluation of Concrete Structures An interesting thing is that the trend seems to go in a more conservative direction when it comes to concrete fatigue. Because the newest Code is the most conservative one! More work is needed in this area and it might be an idea to keep the “old” equation (the one in the EC2-1 (1991)) to calculate the design shear strength when the fatigue capacity is studied. The studied codes generally give too conservative values, especially for high strength concrete. Further work is needed in this area, especially regarding the shear force capacity. - 27 -
Page 1: LICENTIATE THESIS Evaluation of Con
Page 5: Preface This licentiate thesis pres
Page 8 and 9: Evaluation of Concrete Structures I
Page 10 and 11: Evaluation of Concrete Structures I
Page 12 and 13: Evaluation of Concrete Structures 4
Page 14 and 15: A. Simplified check A1. In-situ ins
Page 19 and 20: Evaluation of Concrete Structures G
Page 21 and 22: Lok-Strength & Capo-Strength F [kN]
Page 25 and 26: Evaluation of Concrete Structures a
Page 31 and 32: Evaluation of Concrete Structures t
Page 33: Evaluation of Concrete Structures d
Page 36 and 37: Evaluation of Concrete Structures T
Page 41: 6 Outlook Evaluation of Concrete St
Page 44 and 45: Evaluation of Concrete Structures E
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 and 94:
The obtained stress σ t = 4.45 MPa
Page 95 and 96:
M f,rail moment bearing capacity at
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
Page 144 and 145:
1 − 0.7166 14 ⋅ = 4.71 < 6 ⇒T
Page 146 and 147:
The “new” equation for the desi
Page 149:
Appendix A. Concrete Codes Excerpt
Page 153 and 154:
- 31 -
Page 155 and 156:
- 33 -
Page 157 and 158:
- 35 -
Page 159 and 160:
- 37 -
Page 161 and 162:
- 39 -
Page 163:
- 41 -
Page 167 and 168:
- 45 -
Page 169 and 170:
- 47 -
Page 171 and 172:
- 49 -
Page 173 and 174:
- 51 -
Page 175 and 176:
- 53 -
Page 177:
- 55 -
Page 181 and 182:
- 59 -
Page 183 and 184:
DOCTORAL AND LICENTIATE THESES Divi
show all

LICENTIATE THESIS - Luleå tekniska universitet

Create successful ePaper yourself

Delete template?

Save as template?