Specimen W2 with Cut-off Longitudinal Reinforcement in the Web and a Repetition of 3 for Each Drift Target

The main objective of this study is to test the hypothesis that discontinuities in the longitudinal web reinforcement of a structural wall will cause strain concentration in the longitudinal boundary reinforcement. This strain concentration will affect the seismic response of the structural wall. To achieve this objective, six small-scale structural walls with nominally identical cross sections were built and tested by applying displacement reversals. These specimens were divided into three pairs with two test variables: 1) The continuity of longitudinal reinforcement in the web; 2) Number of cycles for a given drift target.

Specimen W2 had cut-off longitudinal reinforcement in the web. It was subjected to lateral displacement reversals ranging from 0.25% to 5% of the specimen height. Each displacement target was repeated three times.

Specimen W2 developed 0.1 in.-thick splitting cracks at the bases of both the north and south boundary elements during the third cycle at a drift ratio of 4.0%. These splitting cracks were connected to inclined cracks that formed in preceding load reversals. A piece of concrete at the base of the south boundary element spalled off by the end of the third cycle at a drift ratio of 4.0%. Loss of lateral load carrying capacity was detected and buckling of the longitudinal bars in the south boundary element was observed at a drift ratio of 5.0%.

Crack maps, photos and detailed analysis of this specimen are given in the final report.