Role of residual displacements in performance-based seismic assessment, design and retrofit of reinforced concrete buildings and bridge structures: Assessment and mitigation strategies

Abstract

Observation from real earthquake event as well as laboratory testing and numerical studies have demonstrated that most structures designed according to current code provisions might sustain substantial residual (permanent) deformations in the event of a design-level earthquake even if they perform exactly as expected. Residual deformations can result in the partial or total loss of a building if static incipient collapse is reached, if the structure appears unsafe to occupants or if the response of the system to a subsequent earthquake is impaired by the new at rest position of the structure. Furthermore, they can also result in increased cost of repair or replacement of non-structural elements as the new at rest position of the building is altered. These aspects are typically not appropriately reflected in current performance design and assessment approaches.

Following previous work available in literature and recent contributions from the authors, this research project aimed at creating a sound basis to develop a rational performance-based procedure for either design, assessment or retrofit able to account for and reduce the impact of the damage (and associated costs) resulting from residual deformation.

In parallel, refinements and development of emerging self-centering systems based on unbonded post-tensioned techniques, have been considered as a valuable strategy for a direct mitigate of residual deformations for either new design and retrofit.

Direct outcomes of this research project are listed below:

Pettinga, D; Pampanin, S; Christopoulos, C; Priestley, M J N - The role of inelastic torsion in the determination of residual deformations, Journal of Earthquake Engineering, accepted for publication 2007

Pettinga, D - Developments in the prediction and mitigation of residual deformations due to seismic demand, including asymmetric structural response, PhD dissertation, ROSE School, Pavia, Italy, Dec 2006

Pettinga, JD; Priestley, MJN; Pampanin, S; Christopoulos, C - Accounting for the effects on residual deformations due to torsional response, NZSEE Conference, Napier, March 2006 (Awarded Best Student Paper)

Pettinga, D; Pampanin, S; Christopoulos, C; Pristley, MJN - Effects of irregularities on the residual displacements of structures subjected to inelastic torsional response, 4th Worlkshop on Irregular Concrete Structures, Thessaloniki, August 2005

Pettinga, D - Accounting for P-delta effects in structures when using direct displacement-based design, Individual study, ROSE School, Pavia, Italy, December 2006

Uma, SR; Pampanin, S; Christopoulos, C - A probabilistic framework to develop performance objectives based on maximum and residual deformations, 1st ECEES, Geneva, Switzerland, paper n. 731, September 2006

Uma, SR; Pampanin, S; Christopoulos, C - Probabilistic formulation of a performance-based matrix combining maximum and residual deformations, Proceedings of the Annual NZSEE Conference, Napier, March 2006