SEISMIC PERFORMANCE OF POST-TENSIONED INTERIOR SLAB-COLUMN CONNECTIONS WITH AND WITHOUT DROP PANEL

摘要

This paper presents an experimental study on the seismic performance of two three-fifth scale post-tensioned (PT) interior slab-column connection models, one without drop panel and another one with drop panel. The model without drop panel was designed and constructed to represent a typical connection between interior column and post-tensioned flat plate with bonded tendons usually found in Thailand. The other model was intended to represent an improved design of typical post-tensioned slab-column connections by using drop panel. Both models were tested under a constant gravity load. A conventional displacement-controlled cyclic loading routine with monotonically increasing drift levels until failure was adopted to investigate the seismic performance. The experimental results indicated that each model behaved like a linear elastic system with low energy dissipation, and no pinching was observed in the hysteretic loops. The model without drop panel abruptly failed by punching shear shortly after attaining its maximum lateral strength at 2.0% drift, while the improved model experienced a saturation of lateral peak load from about 2.5% to 6.0% drift prior to punching shear. The improved model with drop panel showed considerably more drift capacity and ductility than the one without drop panel. The test results also suggest that the gravity shear ratio be a major variable which governs the drift capacity and ductility of bonded PT interior connections, and that the ACI 318-05's design drift limit could be used for this case.