Report - PEER - University of California, Berkeley

The four-storey reinforced concrete frame building presented in Section 4.1 is thesubject of this example. The structure was modeled numerically and was assumed tobe in a High-seismicity zone in Europe with a hazard compatible with its designseismic action. Response simulations (non-linear models under earthquake inputmotions) were obtained for several input intensities (each using 5 artificiallygenerated accelerograms). The response curve was approximated by an analyticalfunction (average values of the simulation results) and a constant c.o.v. of 25% wasassumed for the sectional lognormal distribution of the response. Performance curveswere obtained for a few different cases (using the same number of ‘experimental’points but distributed differently along the intensity ranges to approximate theresponse curves) and subsequently Annualized Earthquake Losses (AEL) werederived. It was concluded that the approximation of the structural response curvesrepresents a key component of the risk assessment process, with very significantimplications on the values of the expected earthquake losses. Approximation shouldbe based on well-distributed ‘experimental points’ covering low, medium and highinput intensities.0.2AEL [o/oo ]0.100 0.1 0.2 0.3 0.4 0.5 0.6 0.7 . 0.8 0.9Damage index rangeInjuries & FatalitiesContents & EconomicRepair / replacement/Figure 1. Contribution of damage ranges to total expected AEL.There is another important aspect to take into consideration in the risk assessmentprocess, which is concerned with the contribution of the damage ranges to the totalexpected losses. Fig. 1 shows the partial contribution of the damage ranges (0–0.05,0.05–0.1, 0.1–0.15, …) to the total expected losses. It is noted that damage states inthe vicinity of 0.1 are predominantly contributing to the repair and economic losseswhereas ‘human losses’ are practically constant for all damage ranges other than forthe damage values lower than 0.1, for which they are very limited.The key concluding note is that reduction of economic losses is effective in thezones corresponding to low – low/medium damage indices, which can be addressedby the reduction of damage-inducing demands (e.g., drifts) corresponding to lowmediuminput intensities with high probability of occurrence.284