Reinforced concrete slabs belong to the most important and most frequently used structural concrete members. Plastic analysis and the theorems of limit analysis are powerful design tools. However, the application of the theory of plasticity requires a sufficient shear strength and deformation capacity of the plastic regions. A ductile behavior can only be achieved if a premature brittle shear failure or a critical deformation is prevented.
The strength and deformation capacity of reinforced concrete slabs with and without transverse reinforcement have not yet been investigated in a sufficient way. In particular, the questions whether the slab thickness as well as deviations of the principal shear and moment directions from the directions of the in-plane reinforcement influences the shear strength and the deformation capacity, have remained unanswered so far. Also of interest is the minimum transverse reinforcement ratio that eliminates the size effect in thick slabs, leading to ductile failures.
Within the framework of the research project "Deformation Capacity of Structural Concrete" an extensive series of tests on reinforced concrete slab specimens with and without transverse reinforcement was conducted at the Institute of Structural Engineering of the Swiss Federal Institute of Technology (ETH) in Zurich. Brittle shear failures occurred for all specimens without transverse reinforcement. The use of a minimum transverse reinforcement eliminated the size effect, and a ductile flexural failure as well as significantly improved deformation capacity was achieved. Compared to the specimens with coinciding principal moment and in-plane reinforcement directions, the specimens with deviating principal moment and in-plane reinforcement directions showed a lower flexural strength as well as a higher deformation capacity. The test results served as a basis to develop a mechanical model, the so-called extended sandwich model that allows a general treatment of the strength and the deformation capacity of reinforced concrete slabs with and without transverse reinforcement.
The presentation illustrates recent developments from experimental and theoretical investigations. Finally, the discussion of an international competition to predict the load-deformation response of reinforced concrete slabs concludes the lecture.
Dr. Thomas Jaeger is a senior research associate and research engineer at the Institute of Structural Engineering of the Swiss Federal Institute of Technology in Zurich. His research interests include the strength and deformation behavior of reinforced concrete structures. With Prof. Peter Marti, he has conducted an extensive experimental program about the shear strength and the deformation capacity of reinforced concrete slabs. He is also involved in the teaching of reinforced concrete courses I, II, III and building engineering at the Swiss Federal Institute of Technology in Zurich. He has also been an examination expert for reinforced concrete, as well as a lecturer on the subject, at the University of Applied Sciences, in Chur, Switzerland.
Dr. Thomas Jaeger holds a Doctor of technical science (Dr. sc. techn.) degree and a Master of science in civil engineering (Dipl. Bau-Ing. ETH) from the Swiss Federal Institute of Technology (ETH), Zurich, Switzerland. He earned his Bachelor of science in civil engineering (Dipl. Bau-Ing. HTL) from the University of Applied Sciences in Winterthur, Switzerland.
Thursday, October 30th, 2008
03:00 PM EST
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Seminar sponsored by MCEER Networking and Education Programs, MCEER SLC and hosted by the Department of Civil, Structural and Environmental Engineering and the EERI Student Chapter at UB.
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