Experimental and analytical assessment of columns with short lap splices subjected to cyclic loads

Splices in reinforced concrete columns in older buildings, or within the nonparticipating frames in some newer buildings, were typically designed as compression lap splices. Compression lap lengths are typically short (20 to 24db), and only light transverse reinforcement is provided over the lap length. Observations of column damage following earthquakes have revealed that these splices perform poorly; however, relatively sparse information exists to assess the expected performance for typical conditions. To address these needs full-scale columns were tested under a variety of conditions. The test specimens consisted of cantilever columns with a point load applied at the top. The 450 mm square column sections were tested under reversed cyclic lateral load with constant axial load. The primary variables include the level of axial load, the ratio of moment to shear, and the load history. Information on the test program, experimental observations, experimental and analytical results and conclusions are presented herein.; All columns showed nonductile response with limited energy dissipation capacity. Bond deterioration followed by lateral strength degradation was observed around 1.5% lateral drift. Specimens with intermediate and high axial load lost their axial load carrying capacity at 7 and 5% lateral drift respectively.; Uniaxial local bond stress versus slip material models were used to calculate the moment versus slip rotation response. The model was subjected to constant axial load and increasing displacement. The calculated peak lateral load for the model agreed closely with the peak loads obtained in the tests. However, the monotonic moment versus slip rotation response underestimated the lateral drift (or rotation) at which lateral strength degradation initiates.