1 Copyright © 2017 by ASME Proceedings of the 2017 PVP Conference PVP 17 July 16-20, 2017, Waikoloa, Hawaii, USA PVP2017-65273 LOW-DAMAGE DESIGN PHILOSOPHY FOR FUTURE EARTHQUAKE-RESISTANT STRUCTURES Nawawi Chouw The University of Auckland Centre for Earthquake Engineering Research Department of Civil and Environmental Engineering 314-390 Khyber Pass Road, Newmarket, Building 906 Auckland 1023, New Zealand +64 9 923 3512, n.chouw@auckland.ac.nz ABSTRACT Current seismic design philosophy used worldwide tolerates a degree of damage at locations predefined by the designer, as long as a complete structural collapse is precluded. By accepting plastic deformations, the maximum acceptable forces can be controlled and construction costs can be reduced. Major earthquakes, e.g. the Canterbury earthquakes, showed that well-designed structures behave as anticipated. The joints suffered plastic deformation as the designer intended, while the occupants remained alive. Repair costs, however, were often high. Costs also accrue because, post-earthquake, the infrastructure is no longer fit for purpose. These costs are very difficult to predict. Low-damage seismic design, in contrast, can be achieved by activating rigid-like body movement of structural members. Development of forces resulting from structural local deformation can then be prevented. Consequently, associated damage to structural members can be avoided. Recent research outcomes at the University of Auckland Centre for Earthquake Engineering Research will be presented. INTRODUCTION Figure 1 shows a residential house in Japan built according to current seismic design philosophy. Figure 1(a) displays the completed house and Fig. 1(b) shows the house a few weeks prior to completion. To avoid unpredicted damage to the house in the case of earthquakes stronger than anticipated, the steel beams are cut and reconnected using weaker steel plate. Hence, the house is damaged at these weaker links, also called plastic hinges (see Fig. 1(d)). By tolerating damage to the structure at pre-determined locations a more economical structure and controlled damage can be achieved. Figure 1(c) shows an idealized relationship between moment M and curvature . Once the moment reaches the moment My , it remains a constant while the curvature increases, i.e. the hinge will plastify. M y is the maximum capacity of the beam. The joints need to be designed such that they can behave in a ductile manner during the anticipated earthquakes. The key characteristic is not the ability of one particular hinge, rather the whole structure must have sufficient ductility to overcome the earthquake, i.e. the capacity of the structure should be larger than the loading demand. Figure 1. Residential house. (a) Completed house, (b) beam-column joints, (c) moment-curvature relationship and (d) plastic hinge. Elasto-plastic Elastic M y M y  (a) (b) (c) (d)