A. Pinto elsa, jrc, Ispra (VA), Italy

Vulnerability Assessment of Buildings Contribution from Large-scale Laboratory Tests

• A. Pinto

• ELSA, JRC, Ispra (VA), Italy

Reinforced Concrete Buildings

• Represent the largest part of the European building stock at risk, in earthquake prone urban areas

Assessment --- Retrofitting

• Assessment

• Determines the need for seismic retrofit or not
• Identifies particular weakness and deficiencies to be corrected

• Requires:

• Tools to allow rapid screening and empirical evaluation of existing structures

• ‘Solutions’:

• Conventional procedures
• Deformation and displacement based evaluation procedures (Performance and model calibration from Lab Tests required)

Retrofitting ‘guidelines’ (General)

• Key ideas

• Seismic retrofitting combined with architectural remodeling, rehabilitation and/or change in use
• Find a feasible and acceptable solution allowing occupancy during the works

• Technical Requirements

• Any intervention should not prejudice the safety of any part of the building in any aspect
• Continuity of the load path(s) between new and existing elements, floors, …
• Foundations ?!

ICONS - Topic 2 Assessment Strengthening & Repair

Assessment Strengthening & Repair The research work is part of research programme of the ICONS TMR-Network Project Participants: E.C. Carvalho, E. Coelho, A. Campos-Costa, LNEC, Lisbon (PT) A.S. Elnashai, R. Pinho, Imperial College of London (UK) M.N. Fardis, S.N. Bousias, G. Tsionis, University of Patras (GR) GM. Calvi, A. Pavese, M. Recla, University of Pavia (IT) P.E. Pinto, G. Monti, University of Rome (IT) J. Bouwkamp, S. Gomez, University of Darmstadt (DE) E. Alarcon, R. Perera, H. Lutz, Univ. Politecnica of Madrid (ES) A. Plumier, University of Liege (BE) JM. Reynouard, INSA de Lyon (FR) A.V. Pinto, G. Verzeletti, J. Molina, H. Varum, ELSA, JRC, Ispra (IT) Other Contributions: M. Griffith, University of Adelaide, Australia The tests at the ELSA laboratory were financed under the TMR - Large-scale Facilities programme of the European Commission

Tests on 4-storey RC Frames Objectives

• Assessment of a typical RC frame representative of existing buildings

• Design and Construction practice of 40~50 years ago
• Simplified design (8% seismic coefficient), (concrete - C16/20, Steel - Smooth rounded bars), lap-splicing, 90 degrees bent stirrups, no shear reinforcement in joints, Strong beam - Weak column system
• Bare frame vs masonry Infilled frame

• Assessment of retrofitting schemes and techniques

• Selective Retrofitting solutions (balancing Ductility, Strength and Stiffness)
• Shotcrete of existing infill masonry walls
• K-bracing with shear-link (additional strength and damping)

• Other aspects (Plastic-hinge length, Slab participation, Shear and bending deformations of Stocky column, Joints’ behaviour …)

Frame lay-out

Beam Reinforcement

Column Reinforcement

The ICONS Frame

Transport

ICONS Frames

Bare Frame and Selective Retrofit Frame Tests

• Testing Programme

• Pseudo-dynamic tests for increasing earthquake intensities (475, 975 and 2000 yrp)

Instrumentation (Inclinometers)

Instrumentation (Local)

Earthquake Test at ELSA

BARE FRAME 3rd storey - Shear-Drift diagrams

Max. Inter-storey Drift Profiles

BARE FRAME 975 yrp test 3rd Storey collapse

Selective Retrofitting Schemes

Max. Inter-storey Drift Profiles

Max. Drift Profiles

Global Drift

Max. Inter-storey Drift

Infilled Frame with openings

Max. Drift Profiles

Shear-Drift (Storey 1) Infilled and Bare Frame

Global Drift

Max. Inter-storey Drift

Shotcrete

Max. Drift Profiles

Shear-Drift (Storey 1) Shotcrete and Infilled Frame

Column Shear-out

Column Shear-out

Max. Inter-storey Drift

Response maximum values

Concluding Remarks

• RC frame Assessment

• Storey mechanism
• ~1% drift for DE
• Collapse for 1,4xDE (~2.5% drift)

• RC frame with infills Assessment

• Much Higher resistance
• Hiding irregularity
• Much Lower deformation demands
• Structural integrity for 1.4xDE but heavy damage to infills
• Story mechanism markedly prompted after peak resistance (Softening)

ONGOING AND FUTURE PROJECTS AT ELSA

JRC-ELSA Institutional Programme (2003-6)

• Creation of a Virtual Laboratory:

• - To link structural engineering research sites across Europe,
• - Provide data storage facilities and repositories,