Abstract
Recent seismic events have clearly confirmed the vulnerability of existing reinforced concrete (RC) structures. In particular, field observation of structures damaged by L’Aquila earthquake strongly confirmed that premature failure of partially confined (i.e. exterior) beam-column joints was one of the main causes limiting the global structural seismic capacity. Poor attention to details and a lack of adequate transverse reinforcement typically lead to premature brittle shear failure of joints. To provide support to practitioners involved in the L’Aquila reconstruction process, a proper guideline which illustrates the design of local retrofit interventions on structural and non structural elements has been edited by the Italian Civil Protection Department (DPC) and the Laboratories University Network of Seismic Engineering (ReLUIS). In particular, a viable FRP strengthening strategy to increase the seismic performances of partially confined joints (design procedure and installation steps) is widely discussed and presented in the document. To validate the strengthening system recommended in this guideline, an experimental program has been carried out on as-built and FRP strengthened full scale corner RC joints (T shaped joints). After presenting the main guideline recommendations for local strengthening of existing structures, the paper focuses on the experimental program activity; in particular, the specimen design strategy and test setup definition as well as the comparative analysis of the behavior of tested joints.
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- b c :
-
column width
- b b :
-
beam width
- d :
-
beam tip displacement
- d 0 :
-
beam tip displacement for gravity load
- f c :
-
concrete cylindrical compressive strength
- f cm :
-
concrete average cylindrical compressive strength
- h c :
-
column height
- h b :
-
beam height
- p t :
-
average principle tensile stress
- t f,eq :
-
equivalent thickness of FRP dry fibres for each direction.
- A g = b c .h c :
-
column gross concrete area
- E eq :
-
energy dissipation associated to the equivalent elastoplastic system
- L :
-
beam free length
- P :
-
column axial load
- V c :
-
column shear
- V c,MAX :
-
experimental column shear peak value
- V jh :
-
joint panel shear strength
- ε y :
-
steel rebars yielding strain
- ε FRP :
-
FRP strain
- ν = P/ (A g .f cm ) :
-
axial load ratio
- μ :
-
subassemblage ductility
- Δ u :
-
ultimate drift
- Δ y :
-
drift at yielding
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Acknowledgments
This study was performed in the framework of PE 2010–2013: joint DPC-ReLUIS project, Task 3.1. The materials used for joints strengthening were donated by Mapei Spa, Milano.
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Prota, A., Di Ludovico, M., Balsamo, A., Moroni, C., Dolce, M., Manfredi, G. (2014). FRP Local Retrofit of Non-Conforming RC Beam-Column Joints. In: Ilki, A., Fardis, M. (eds) Seismic Evaluation and Rehabilitation of Structures. Geotechnical, Geological and Earthquake Engineering, vol 26. Springer, Cham. https://doi.org/10.1007/978-3-319-00458-7_14
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DOI: https://doi.org/10.1007/978-3-319-00458-7_14
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