Report - PEER - University of California, Berkeley

5 th floor disp. [cm]0.60.0-0.6CC = 0.15experimentpredictionTime [s]3 4 5 6 7 8 9 10 11 12Figure 8a. Low level response — preceding load is not considered.5 th floor disp. [cm]0.60.0-0.6CC = 0.75experimentpredictionTime [s]3 4 5 6 7 8 9 10 11 12Figure 8b. Low level response — preceding load is considered.3.2 Near Collapse Performance, Local FailureThe prediction for the last — fourth run was completely wrong (Fig. 9a). It wasrealized during post-experimental analysis that in the second run the boundaryreinforcement at the base of the wall experienced large ductility demand. Since some(low-diameter) bars in that area were quite brittle, they most probably failed. Sincethe first author of this paper was interested only in global EDPs (like topdisplacement) he overlooked the possibility of this failure, which was notautomatically detected either by DRAIN or by OpenSees. When the potentiallyfractured reinforcement was omitted in the analysis after the second run, thecorrelation between experiment and analysis was good (Fig. 9b). This exampledemonstrates that global damage measures may fail to predict damage level in RCstructures. It should be emphasized that the top drift of the wall was less than 1%even in the fourth run, which should not indicate major damage by any acceptedcriterion. However, the wall, designed according to modern code, was very close tocollapse (Fig. 7). It has been also demonstrated that standard models may haveproblems simulating near collapse behavior.5 th floor disp. [cm]5.00.0-5.0CC = 0.44experimentpredictionTime [s]3 4 5 6 7 8 9 10 11 12Figure 9a. Near collapse level — brittle reinf. is included into model.299