Geiker, Mette Rica

Pease, Bradley Justin

Stang, Henrik

Weiss, Jason

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 16, 2017Photogrammetric Assessment of Flexure Induced Cracking of Reinforced ConcreteBeams under Service LoadsPease, Bradley Justin; Geiker, Mette Rica; Stang, Henrik; Weiss, JasonPublication date:2006Link back to DTU OrbitCitation (APA):Pease, B. J., Geiker, M. R., Stang, H., & Weiss, J. (2006). Photogrammetric Assessment of Flexure InducedCracking of Reinforced Concrete Beams under Service Loads.Department of Civil EngineeringBrad Pease, Mette Geiker,              Henrik Stang, and Jason Weiss2ND International RILEM Symposium, September 11-13, 2006Photogrammetric Assessment of Flexural Induced Cracking in Reinforced Concrete Beams under Service LoadsBYG  DTUBYG  DTUDepartment of Civil EngineeringOutline of Today’s Talk• Motivation & Goal• Experimental Investigation – Sample Geometry– Three-Dimensional Photogrammetry Technique• Test Results– Crack Geometry– Crack Measurements• ConclusionsBYG  DTUBYG  DTUDepartment of Civil EngineeringOutline of Today’s Talk• Motivation & Goal• Experimental Investigation – Sample Geometry– Three-Dimensional Photogrammetry Technique• Test Results– Crack Geometry– Crack Measurements• ConclusionsBYG  DTUBYG  DTUDepartment of Civil EngineeringMotivation and Goal• Motivation– Cracking in concrete affects ingress and corrosion           (i.e. service life)– Cracking in reinforced concrete is complicated by slip and separation at reinforcing bar• Goal– Quantify crack geometry in reinforced concrete beam during loadingBYG  DTUBYG  DTUDepartment of Civil Engineering Experimental Observation of Cracks:  Sample Geometry and Loading• Reinforced beams(150 x 150 x 600 mm)150 mm600 mm150 mm~42 mm150 mmBYG  DTUBYG  DTUDepartment of Civil Engineering Experimental Observation of Cracks:  Sample Geometry and Loading• Reinforced beams (150 x 150 x 600 mm)• Face of concrete removed• Exposed reinforcement and  aggregate600 mm150 mm150 mm150 mm150 mmCutting Plane~42 mm150 mm150 mm150 mmBYG  DTUBYG  DTUDepartment of Civil Engineering Experimental Observation of Cracks:  Sample Geometry and Loading• Reinforced beams (150 x 150 x 600 mm)• Face of concrete removed• Exposed reinforcement and  aggregate • 3-Point bending– 1.0 and 1.8 times estimated cracking load (13 and 25.2 kN)– 35 kN600 mm150 mm150 mm150 mm150 mmCutting Plane~42 mm150 mm150 mm150 mmBYG  DTUBYG  DTUDepartment of Civil Engineering3-D Photogrammetry• Photogrammetry quantifies cracking during loading• Two digital cameras placed equidistant from sample, focused on same point collect images• Images separated into a mesh by software– Individual mesh box = facetLeft CameraRight CameraSampleFacetBYG  DTUBYG  DTUDepartment of Civil Engineering 3-D Photogrammetry: General Measurement Process• Coordinates assigned to facet corner and center by grayscale variation• System tracks movement of facet center and cornersWhite line – original locationBlack line – deformed shapeBYG  DTUBYG  DTUDepartment of Civil Engineering• Grayscale contrast obtained by speckle pattern 3-D Photogrammetry: Surface PreparationBYG  DTUBYG  DTUDepartment of Civil Engineering• Sample deformation measured as mesh movements3-D Photogrammetry: Deformation MeasurementUnloaded CrackedBYG  DTUBYG  DTUDepartment of Civil EngineeringOutline of Today’s Talk• Motivation & Goal• Experimental Investigation – Three-Dimensional Photogrammetry Technique• Test Results– Crack Geometry– Crack Measurements• ConclusionsBYG  DTUBYG  DTUDepartment of Civil Engineering3-D Photogrammetry: Crack Geometry• All beams loaded at constant rate, maximum – 3 min. unloaded – 3 min.• Video of measured deformation projected on beam surface• Crack opening measurements from tension face and near reinforcementBYG  DTUBYG  DTUDepartment of Civil EngineeringCrack Measurements: Crack Shape• Load vs. crack width at various loadings from two locations• V-Shaped crack0 0.1 0.2 0.3 0.4 0.5Crack Width, w (mm)010203040Load (kN)Maximum Load13 kN25.2 kN35 kN0 0.02 0.04 0.06 0.08Crack Width, w (mm)010203040Load (kN)Maximum Load13 kN25.2 kN35 kNBYG  DTUBYG  DTUDepartment of Civil EngineeringCrack Measurements: Slip and Separation• Elastic slip response, inelastic separationx, Slipy, Separation0 0.1 0.2 0.3 0.4 0.5Crack Width, w (mm)00.030.060.090.120.15Displacement (mm)Displacement Direction13 kN - Slip13 kN - Separation35 kN - Slip35 kN - Separation• Slip and separation vs. crack width near tensile faceBYG  DTUBYG  DTUDepartment of Civil EngineeringCrack Measurements: Slip and Separation• Initiation of slip and separation– At estimated cracking load~4 µm measured slip and separation– Measured deformations close to resolution, results inconclusive0 0.01 0.02 0.03 0.04Crack Width, w (mm)-0.0100.010.020.03Displacement (mm)Displacement Direction13 kN - Slip13 kN - SeparationBYG  DTUBYG  DTUDepartment of Civil EngineeringConclusions• 3-D Photogrammetry used to quantify cracking under flexural loading• Slip behavior between reinforcement and concrete is elastic while separation behavior is inelastic • Slip and separation between reinforcement and concrete initiates after opening of crack at tensile faceBYG  DTUBYG  DTUDepartment of Civil EngineeringAcknowledgementsOtto Mønsted Foundation – Travel FundThe Velux Funds: Villam Kann Rasmussen Foundation – Funding for Aramis 3-D Photogrammetry Equipment

Photogrammetric Assessment of Flexure Induced Cracking of Reinforced Concrete Beams under Service Loads

Reinforced concrete structures are known to crack due to restrained shrinkage, temperature gradients, application of load, and expansive reactions. Cracks provide paths for rapid ingress of moisture, chlorides, and other aggressive substances, which may affect the long-term durability of the structure. For example, concrete cracks located at the reinforcing steel may contribute to a rapid corrosion initiation and propagation. Previous research has shown that cracked reinforced concrete under static flexural loading may have an increased ingress of chloride ions along the reinforcement/concrete interface. The aim of this paper is to provide a detailed description of the development of cracks in reinforced concrete under flexural load. Cracking at both realistic service load levels (1.0-1.8 times estimated cracking load) and unrealistically high service load levels (&gt; 0.5 times beam capacity) has been investigated. These load levels result in relatively small cracks 

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Photogrammetric Assessment of Flexure Induced Cracking of Reinforced Concrete Beams under Service Loads

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