Bursting and Spalling in Pretensioned U-Beams - Ferguson ...

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Table D.1 Beam 1 match-cured cylinder compressive strengthsHours afterBatchingRelease Pointf c ' (ksi)12.5 1.98 1.9813.5 3.53 3.5314.5 4.66 4.6615 4.9715 5.185.0715.5 5.30 5.3016.25 5.8416.25 5.9016.75 6.1316.75 6.2016.75 6.3217.5 6.2917.5 6.4217.5 6.615.876.226.44Hours afterBatchingHot Spotf c ' (ksi)12.5 3.3412.5 3.413.3813.5 4.74 4.7414.5 5.44 5.4415 5.9115 5.835.8715.5 6.0815.5 6.386.2317.75 6.9217.75 6.996.9619.5 8.3919.5 8.098.24Table D.2 Beam 1 match-cured cylinder splitting-tensile strength at releaseHours afterBatchingTop Flangef sp ' (ksi)18 0.7918 0.83 0.7718 0.68220
Compressive Strength (ksi)131197f c ' (28d) = 11.6 ksiAmbient-Cured Cylinders50 10 20 30 40 50 60Days after BatchingFigure D.2 Beam 1 ambient-cured cylinder compressive strengthsTable D.3 Beam 1 ambient-cured cylinder compressive strengthsDays afterBatchingAmbientf c ' (ksi)1.1 7.191.1 7.341.1 7.347.301.1 7.347.1 11.037.1 10.837.1 10.7410.807.1 10.5814.3 10.9014.3 10.8514.3 10.8410.8414.3 10.7628.1 11.5728.1 11.7211.6549.3 11.9949.3 11.87 11.9649.3 12.02221
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CopyrightbyDavid Andrew Dunkman2009
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Bursting and Spalling in Pretension
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Bursting and Spalling in Pretension
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2.4.2.3 Itani & Galbraith, 1986 ...
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4.2.2.4 Beam 1: Lateral-Bar Burstin
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List of TablesTable 2.1 Range of st
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Figure 2.25 Mechanical gage points
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Figure 3.30 Thermocouple placement
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CHAPTER 1Introduction1.1 IMPETUS FO
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At present, current end-region deta
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Figure 2.1 Severe cracking in a pre
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through use of tensioned, high-stre
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As splitting stress is bond-related
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Figure 2.6 Effect of bursting & spa
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magnitude of the end-region transve
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FEA can readily output color maps o
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2.3.1.3 Plastic Analysis of Beam En
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force can increase by 400% (Yettram
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2.4 EXPERIMENTAL STUDIES OF BURSTIN
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The trial specimens included one 40
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mechanical gage (2 in. gage length)
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Bursting stress(normalized by prest
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proprietary post-tensioning anchors
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Though Marshall and Mattock placed
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ectangular beam” (p. 21). At high
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Most beams observed to crack did so
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The behavior of these beams was dom
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2.4.2 Studies of End-Region Transve
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Figure 2.28 I-beams studied by Mars
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transverse forces compared to those
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(a) Actual spalling stress variatio
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stirrups in Gergely, Sozen and Sies
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50% more reinforcement than require
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strength concrete, increasingly hig
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the reinforcement located within th
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Typical crack patterns for the beam
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“Very common”crack locationPred
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Figure 2.38 Typical gage locations
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2.4.2.7 Smith et al., 2008Most rece
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the provided transverse reinforceme
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Itani and Galbraith (1986) reported
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Figure 2.45 Confining reinforcement
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cracks located along lines of prest
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odies relevant to pretensioned conc
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than that in another shape. For thi
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Figure 2.47 Required splitting rein
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No attempt was made in the Tentativ
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No citation is provided in the PCI
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Section Propertiesy b22.4 in.A 1120
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minimum for greater skews. For beam
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treatment (counting the transverse
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Pretensioned/post-tensioned beams h
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Figure 2.57 Harped strands in webs
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transversereinforcementwithin voidp
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2.8 SUMMARYIn this chapter, literat
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3.2.1.1 Linear and Nonlinear Stress
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Empirical expressions can be used t
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where: 0.021 = spalling force,
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3.3 CONCRETE PROPERTIES3.3.1 Concre
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It was reasoned that the dimensiona
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Splitting tensile-strength testing
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For temperature-match curing, therm
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3.4.1 Reinforcing-Bar Mechanical Te
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Grade 60 rebar yielded at 65 ksi an
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Equation 3.10where:ε1,2 = gage str
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Figure 3.17 Typical strand failure
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SouthNorth North120NorthSouthFigure
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Beam 1 also included an additional
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Figure 3.22 Strand strain-gage inst
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Figure 3.25 Interface board used to
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eam has a “hot spot” (measureme
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3.6 BEAM FABRICATION3.6.1 Beam Cast
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Figure 3.33 Installing the interior
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In order to use a pretensioning bed
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standardside-formprofilespecialtape
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Figure 3.41 Strands installed, tens
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Correspondence between the values o
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Figures 3.45 to 3.50 show the fabri
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Figure 3.49 Casting end block (and
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Figure 3.52 Detensioning by gradual
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CHAPTER 4Results & Discussion4.1 OV
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The strain time history for each ga
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1DNorthSouth1E18 ksi1C1C,E1D1521B1B
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Figure 4.4 Beam 1 prestress losses
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crack adjacent to this location was
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The temperatures in the end blocks
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Table 4.4 Beam 2 applied prestressi
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Figure 4.10 Beam 2 prestress losses
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terms of force distribution seems t
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limits were only exceeded at locati
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spalling stresses were measured in
Page 186 and 187: transverse reinforcement contained
Page 188 and 189: Based on Figure 4.18, the 4% Pi des
Page 190 and 191: Uniform and linearly-decreasing tra
Page 192 and 193: 4.3.5 Contributing Factors to High
Page 194 and 195: stress ratio multiplied by a typica
Page 196 and 197: Figure 4.25 Relation between total
Page 198 and 199: 4.4.1 Recommended Texas U-Beam Rein
Page 200 and 201: Figure 4.28 Proposed end-region det
Page 202 and 203: At present, AASHTO LRFD (2009) lack
Page 204 and 205: CHAPTER 5Conclusions5.1 SUMMARY OF
Page 206 and 207: tested at transfer and under shear
Page 208 and 209: APPENDIX ADatabase of Transverse-Ba
Page 210 and 211: 194Figure A.1 U-beam with skewed en
Page 212 and 213: 196Figure A.3 Shallow Texas bulb te
Page 214 and 215: 198Figure A.5 Lightweight-concrete
Page 216 and 217: 200Figure A.7 Washington bulb tee (
Page 218 and 219: 202Figure A.9 Nebraska bulb tees an
Page 220 and 221: 204Figure A.11 Nebraska bulb tees a
Page 222 and 223: 206Figure A.13 Shallow I-beams
Page 224 and 225: where:= lower-bound concrete tensil
Page 226 and 227: B.3.4 Transmission Length (Clause 6
Page 228 and 229: Equation B.11where:= bursting force
Page 230 and 231: 50High Web gage4030Max Moment heigh
Page 232 and 233: C.2 CONCRETE RELEASE STRENGTHA bott
Page 234 and 235: Table C.1 Specimen Design for Beams
Page 238 and 239: D.1.2 Beam 28Release-Point Cylinder
Page 240 and 241: Cylinder Strength (ksi)131197Ambien
Page 242 and 243: D.2 REINFORCING-BAR MODULUS & STREN
Page 244 and 245: APPENDIX EEnd-Block Temperature Pro
Page 246 and 247: E.2 BEAM 2T max = 142°F∆T = 30°
Page 248 and 249: REFERENCESREFERENCED STANDARDSAmeri
Page 250 and 251: Fédération Internationale du Bét
Page 252 and 253: Davis, R.T.; Buckner, C.D. & Ozyild
Page 254 and 255: Lin, T.Y. & Burns, N.H. (1981), Des
Page 256 and 257: Stone, W.C. & Breen, J.E. (1984),
Page 258: VITADavid Andrew Dunkman was born 2
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