Report - PEER - University of California, Berkeley

eal damage data, rather than theoretical predictions; structural calculation of damagehas often been notoriously inaccurate. Moreover, when dealing with a very largepopulation of buildings, an intensity based model with few parameters has someappeal over a HAZUS type model with many parameters which may be difficult toestimate on a country wide scale. Also, insurance personnel without a background instructural engineering or engineering seismology tend to prefer the simpler intensityapproach to one producing answers from a complex ‘black box’.In 1998, two of the authors were involved in the preparation of seismic lossestimates for the whole of a large industrialized and highly seismic country (Turkey).Despite the reservations noted above, a HAZUS methodology, suitably adapted forlocal conditions, was adopted (Bommer et al., 2002). Early in the project, thedevastating Kocaeli and Düzce earthquakes in Western Turkey occurred, creating alarge amount of damage data for events which were rich in instrumental recordings,and which affected a large stock of rather uniform recent construction; these eventsprovided an ideal (and rare) opportunity for validation. This paper discusses previouswork using these data which suggested that the HAZUS methodology did not (in thiscase) provide significant predictive advantages over intensity based methods. Thepaper goes on to describe a Monte Carlo based modification to HAZUS which givessome insights into the reasons for these poor predictions of damage.2. PREVIOUS VALIDATIONS, USING TURKISH DAMAGE DATA2.1 Zones Dominated by Ground Shaking DamageA study by Spence et al. (2003) compared predicted damage with that reported by theAIJ (2001) and EEFIT (2003) at three locations in the epicentral area of the Kocaeliearthquake. The ground-shaking demand was defined using smoothed elastic spectra,selected to agree with the recordings from the Kocaeli earthquake, and modified tomatch local soil conditions; it was also defined in terms of intensity.The study focused on the predicted performance of reinforced concrete framebuildings, of either ‘good’ or ‘poor’ quality, and unreinforced masonry buildings.The estimation of damage using the capacity spectrum approach was based upon theHAZUS methodology (FEMA, 1999), with adaptations for Turkish conditions, whilethat using intensities employed vulnerability functions derived from damage datafrom previous Turkish earthquakes; further details are given in Spence et al. (2003).The study concluded that neither displacement-based (i.e., HAZUS-based) norintensity-based approaches showed good agreement with the observed results (Fig. 1).398