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Flexural Behavior of Drilled Shafts with Minor Flaws
Drilled shafts are among the most popular deep foundation solutions because of their cost-effectiveness, their high load-carrying capacity, and the minimal disturbance (vibration, noise) that they cause to the surrounding environment. However, due to the nature of their construction, minor structural flaws are sometimes introduced without the knowledge of the designer. These flaws can consist of small voids, soil inclusions or drilling slurry mixing with concrete; weak concrete; misalignment of steel rebar cages; and corroded rebars. Quality assurance procedures, which include non-destructive evaluation (NDE) techniques, are implemented to ensure that constructed drilled shafts are free of such flaws (particularly voids and soil inclusions). However, these procedures are not always successful, especially for small flaws, and some small flaws unavoidably go undetected. Drilled shafts are often designed to carry lateral loads, for example, drilled shafts in bridge abutments, cantilevered or tied-back retaining walls or bridge and building piers subjected to asymmetric vertical loads or lateral loads from wind, vessel impact or seismic events. Hence, it is important that designers consider the effects of minor, undetectable flaws on the flexural resistance of drilled shafts. This paper presents the results of an experimental study that consisted of scaled laboratory tests and large-scale structural laboratory tests designed to investigate the flexural capacity of drilled shafts with such minor undetectable flaws. The study showed that a concrete void occupying 15 percent of the cross-sectional area of the drilled shaft, penetrating inside the core of the shaft (defined by the rebar cage) arid having a length along the centerline of the shaft equal to the diameter of the shaft, may reduce the flexural resistance of the shaft by about 32 percent of the resistance of an intact shaft. The ductility of the shaft due to the presence of an anomaly was also affected. Conclusions concerning loss of capacity and ductility for other flaws are also presented for pure flexural loading.
Flexural Behavior of Drilled Shafts with Minor Flaws
Drilled shafts are among the most popular deep foundation solutions because of their cost-effectiveness, their high load-carrying capacity, and the minimal disturbance (vibration, noise) that they cause to the surrounding environment. However, due to the nature of their construction, minor structural flaws are sometimes introduced without the knowledge of the designer. These flaws can consist of small voids, soil inclusions or drilling slurry mixing with concrete; weak concrete; misalignment of steel rebar cages; and corroded rebars. Quality assurance procedures, which include non-destructive evaluation (NDE) techniques, are implemented to ensure that constructed drilled shafts are free of such flaws (particularly voids and soil inclusions). However, these procedures are not always successful, especially for small flaws, and some small flaws unavoidably go undetected. Drilled shafts are often designed to carry lateral loads, for example, drilled shafts in bridge abutments, cantilevered or tied-back retaining walls or bridge and building piers subjected to asymmetric vertical loads or lateral loads from wind, vessel impact or seismic events. Hence, it is important that designers consider the effects of minor, undetectable flaws on the flexural resistance of drilled shafts. This paper presents the results of an experimental study that consisted of scaled laboratory tests and large-scale structural laboratory tests designed to investigate the flexural capacity of drilled shafts with such minor undetectable flaws. The study showed that a concrete void occupying 15 percent of the cross-sectional area of the drilled shaft, penetrating inside the core of the shaft (defined by the rebar cage) arid having a length along the centerline of the shaft equal to the diameter of the shaft, may reduce the flexural resistance of the shaft by about 32 percent of the resistance of an intact shaft. The ductility of the shaft due to the presence of an anomaly was also affected. Conclusions concerning loss of capacity and ductility for other flaws are also presented for pure flexural loading.
Flexural Behavior of Drilled Shafts with Minor Flaws
Sarhan, Hazem (author) / Tabsh, Sami W. (author) / O'Neill, Michael (author) / Ata, Alaa (author) / Ealy, Carl (author)
International Deep Foundations Congress 2002 ; 2002 ; Orlando, Florida, United States
Deep Foundations 2002 ; 1136-1150
2002-02-01
Conference paper
Electronic Resource
English
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