Mechanical Damage and Crack Growth in Concrete
Alberto Carpinteri
Preference :
Fracture mechanics technology has received considerable attention in recent years and has advanced to the stage where it can be employed in engineering design to prevent against the brittle fracture of high-strength materials and highly constrained structures. While research continued in an attempt to
extend the basic concept to the lower strength and higher toughness materials, the technology advanced rapidly to establish material specifications, design rules, quality control and inspection standards, code requirements, and regulations for safe operation. Among these are the fracture toughness testing procedures of the American Society of Testing Materials (ASTM), the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Codes for the design of nuclear reactor components, etc.
Structural elements can fail in many different ways. The ultimate load condition may be reached by a combination of plastic flow, slow or fast crack propagation, depending on the material strength, ductility and toughness, and the size of the structural components. Highly constrained and/or
brittle materials may result in sudden crack formation and unstable crack propagation, whereas less constrained and/or more ductile materials are more likely to fail progressively by plastic yielding. In those situations, the presence of initial cracks do not play an important role in the failure process.
In many cases, however, the terminal condition is preceded by slow crack growth that continues even into the stage of global structure failure. There are other situations where slow crack growth may occur simultaneously with plastic flow and the final failure can still be catastrophic.
The current fracture mechanics literature contains a multitude of ideas, concepts, and criteria, that are not always consistent one with the other. Plastic Limit Analysis and Linear Elastic Fracture Mechanics are two theories that address failure of structural components with very ductile and very
brittle behavior, respectively. They are unable to account for the slow crack growth and the softening behavior in concrete structures aside from the effect of material heterogeneity that is connected with the brittleness of concrete.
extend the basic concept to the lower strength and higher toughness materials, the technology advanced rapidly to establish material specifications, design rules, quality control and inspection standards, code requirements, and regulations for safe operation. Among these are the fracture toughness testing procedures of the American Society of Testing Materials (ASTM), the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Codes for the design of nuclear reactor components, etc.
Structural elements can fail in many different ways. The ultimate load condition may be reached by a combination of plastic flow, slow or fast crack propagation, depending on the material strength, ductility and toughness, and the size of the structural components. Highly constrained and/or
brittle materials may result in sudden crack formation and unstable crack propagation, whereas less constrained and/or more ductile materials are more likely to fail progressively by plastic yielding. In those situations, the presence of initial cracks do not play an important role in the failure process.
In many cases, however, the terminal condition is preceded by slow crack growth that continues even into the stage of global structure failure. There are other situations where slow crack growth may occur simultaneously with plastic flow and the final failure can still be catastrophic.
The current fracture mechanics literature contains a multitude of ideas, concepts, and criteria, that are not always consistent one with the other. Plastic Limit Analysis and Linear Elastic Fracture Mechanics are two theories that address failure of structural components with very ductile and very
brittle behavior, respectively. They are unable to account for the slow crack growth and the softening behavior in concrete structures aside from the effect of material heterogeneity that is connected with the brittleness of concrete.
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| Mechanical Damage and Crack Growth in Concrete |
Content :
- Historical review: strength of materials and fracture mechanics
- Fracture of concrete and brittle materials
- Three-point bending of slab with edge crack
- Center cracked slab in tension
- Off-center compression of slab with edge crack
- Steel reinforced beam with crack in bending
- Panel with opening and diagonal cracks
- Fracture testing and design
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