Report - PEER - University of California, Berkeley

3.3 Damage Modeling and Damage Measure (DM)Based on work carried out at the University of Washington (Berry and Eberhard,2003), the two damage measures considered in this study are the onset of concretespalling and reinforcing bar buckling. Spalling of the concrete cover is an importantdamage measure because it represents the first flexural damage states wherein therepair costs may be significant. The onset of buckling of longitudinal reinforcing barsis another critical damage state because it significantly reduces the structure'sfunctionality and has implications for structural safety. Based on extensive statisticalanalysis of experimental data, Berry and Eberhard proposed two fragility functions(shown on the left in Figure 5) that describe the probability of achieving these damagestates given a seismic demand in terms of the tangential drift in the column.P(DM|EDP)1.00.80.60.40.20.0SpallingBar Buckling0 2 4 6 8EDP, Drift (%)P(Closure|EDP)1.00.80.60.40.20.00 2 4 6 8EDP, Drift (%)Figure 5. Likelihood of damage and closure probability as a function of EDP.3.4 Decision Variable (DV)Porter (2004) conducted a survey (Table 1) of a small group of bridge inspectors fromdepartments of transportation across the country to determine how decisions onbridge closure are made. The respondents self-rated their expertise as 4 or 5 (on a 5point scale) in responding to questions.Decision DamageHorizontaloffset atTable 1. Sample section of surveyNoclosureClose1-3daysClose>3daysOpen withreducedspeed< ½ in < ½ in < ½ in < ½ in½ - 1 in ½ - 1 in ½ - 1 in ½ - 1 injoint > 1 in > 1 in > 1 in > 1 inConcrete No No No NoSpalling Yes Yes Yes YesBar No No No NoBuckling Yes Yes Yes Yes70