Report - PEER - University of California, Berkeley

where D is the maximum drift and N is the number of load cycles (computedusing the drift history). Empirical parameters in Eq. 2 are calibrated tominimize the dispersion of the data and are defined as follows: a=0.252,b=0.645, c=0.0178, d=0.819.• Joint shear strain in combination with the number of load cycles: Afunctional EDP that includes both maximum joint shear strain and number ofload cycles is considered the most desirable EDP:F +b d= aγ cN(3)where γ defines the maximum joint shear strain, N defines the number of loadcycles (computed using the drift history) and empirical parameters are definedas follows: a = 1.46, b = 0.481, c=0.200, d = 0.309.3.2 Damage StatesDamage measures (DMs) describe the damage sustained by a component during anearthquake. In this study, damage is quantized into discrete damage states. Datacharacterizing the development of damage in the previously discussed laboratory testspecimens as well as research results, documentation providing guidelines for postearthquakerepair and interviews with professional were used to identify a series ofdamage states that (1) best characterize the progression of damage in reinforcedconcrete beam-column joints and (2) best determine the appropriate method of repairfor the component. These damage states are1. Initial cracking at the beam-column interface2. Initial cracking within the joint area3. Maximum crack width is less than 0.02 in. (5 mm)4. Maximum crack width is greater than 0.02 in. (5 mm)5. Beam longitudinal reinforcement yields6. Maximum crack width is greater than 0.05 in. (1.3 mm)7. Spalling of at least 10% joint surface concrete8. Joint shear strength begins to deteriorate9. Spalling of more than 30% joint surface concrete10. Cracks extend into the beam and/or column11. Spalling of more than 80% joint surface concrete12. Crushing of concrete extends into joint core13. Failure due to (a) buckling of longitudinal steel reinforcement, (b) loss of beamlongitudinal steel anchorage within the joint core, or (c) pull-out ofdiscontinuous beam longitudinal steel reinforcement214