Restrepo, Mander, and Holden 2001
The authors discuss design aspects of a new generation of structural systems intended to minimize damage. The paper briefly discusses the results of a test program on precast/post-tensioned structural wall systems. This system is constructed to be low cost while ensuring elastic response in a large earthquake. Structural damage is acceptable if collapse is prevented. Therefore, critical regions on the structure are designed for ductility and energy dissipation. The remainder of the structure is designed for sufficient strength to ensure the energy-dissipating mechanism can develop and be maintained. The authors address previous design methodology for cantilever walls with unbounded pre-stressed tendons and energy-dissipating devices. The system is then evaluated experimentally for its dynamic response.
System Concept
The structure is composed of precast concrete walls and unbonded tendons. When a large lateral displacement load is applied, a gap opens at the base of the wall. The opening of a large gap at the base of the wall induces large compressive strains at the corner of the wall. During small amplitude displacements, the joint at the wall-foundation beam remains closed and most deformations take place within the wall panel and the foundation structure. A gap opens as decompression is reached at one end. The response of the wall is non-linear elastic, resulting in little structural damage and residual deformations.
Experimental Study, Results and Discussion
Experimental tests were conducted on five walls. To enable a comparison of the dynamic response, the backbone moment-curvature response employed in the analyses was identical for both monolithic and jointed wall models. The response of the monolithic wall was modeled using a Takeda hysteresis rule; and the response of the jointed wall was modeled using an origin-centered rule. The monolithic wall was designed for ductile response and the jointed wall was designed to match the capacity of the monolithic wall. Features of testing units were varied to include post tensioned only, incorporating energy dissipation devices in the way of dog-bone bars, being under constant axial load, and being precast.
Experiments showed that jointed walls experienced no residual drifts or structural damage after a major earthquake.
Reference
Restrepo, J.I., Mander, J. and Holden, T.J. (2001). “New Generation of Structural Systems for Earthquake Resistance,” Report: Engineering an Earthquake Resilient New Zealand, New Zealand Society for Earthquake Engineering, Wairakei, New Zealand.