Experimental study on elasto-plastic dynamic behavior of steel-pipe pier models

In order to study dynamic behavior of steel-pipe pier models, shaking test is conducted in which a simple harmonic exciting method is applied. The dimensions of the steel-pipe pier models are diameter: 96 mm, height: 500 mm and thickness: 1.5 mm. A lead block with 1.2 ton mass is set on the top of pier model to mock up mass of the superstructure. In order to investigate the effects of filled concrete on strength and ductility of piers at earthquake, each three pier models with/without filled concrete are used. The results obtained from this study are as follows: 1) in case of no concrete filled pier models, increasing an amplitude of input acceleration, local buckling with elephant foot bulge mode is developed near the bottom on one side of shaking direction and the mode is grown up; finally, the model is totally collapsed; 2) in case of concrete filling pier models, the elephant foot bulge buckling mode is generated around near the bottom with increasing acceleration amplitude; then the cracks are developed in both sides of buckled area in shaking direction, but the models do not collapse and still vibrate with low amplitude against high acceleration input; and 3) it is seen that the ductility of steel-pipe piers can effectively be increased by filling concrete.