Effect of Tie Bar Volume on the Seismic Performance of Polypropylene Fiber Reinforced Columns based on Hybrid Loading Experiments

Abstract

It has been shown based on previous research that damage of RC bridge columns can be mitigated and ductility capacity can be enhanced by implementing polypropylene fiber-reinforced cement composites (PFRC) at the plastic hinge. The bridging action of polypropylene fibers which can mitigate crack propagation and widening of cracks has similar action with the lateral confinement by tie bars. Thus, it is likely that use of PFRC can reduce amount of tie bars required for ductility capacity enhancement. This paper shows a feasibility study for reducing an amount of tie bars by implementing PFRC at the plastic hinge. Based on a hybrid loading experiment and a nonlinear dynamic response analysis, it is shown that it is feasible to reduce an amount of tie bars by half by using PFRC though failure of the column slightly increases.

Effect of Volume Tie Ratio in the Engineered Cementitious Composites Plastic Hinges on the Seismic Performance of RC Composite Bridge Columns

“…The prototype of the scaled bridge columns in the target experiment [ 11 ] was the full-size bridge column incorporating ECC in the region of the plastic hinge (C1-6) [ 10 ] as mentioned above. The dimension and configuration of the prototype column are shown in Figure 1 .…”

“…In the target experiment [ 11 ], two scaled bridge columns using ECC at the column base with the scale ratio of 6/35 named by PFRC-1 and PFRC-2 were designed as shown in Figure 2 . It should be noted that the ECC with a designed compressive strength of 40 MPa was used in the target experiment [ 11 ] which had the same mixture as that of C1-6.…”

“…In the target experiment [ 11 ], two scaled bridge columns using ECC at the column base with the scale ratio of 6/35 named by PFRC-1 and PFRC-2 were designed as shown in Figure 2 . It should be noted that the ECC with a designed compressive strength of 40 MPa was used in the target experiment [ 11 ] which had the same mixture as that of C1-6. Except for the volume tie ratio in the ECC portion in the two columns, both columns had identical dimensions and longitudinal reinforcements as shown in Figure 2 b–d.…”

“…The test results showed that the implementation of ECC in the plastic hinge significantly reduced the damage and maintained the functionality of the bridge after an earthquake. In order to clarify the effect of volumetric tie ratio in ECC plastic hinges further, Zhang et al [ 11 ] conducted the hybrid-loading tests on two scaled columns with different volumetric tie ratios based on C1-6. Experimental results showed that the column with reduced ties still exhibited a comparable seismic performance as that without the reduction in ties.…”

“…Therefore, the effect of the volume tie ratio in ECC plastic hinges on the seismic performance of the RC composite column have yet to be clarified. To investigate the effects of the volume tie ratio in ECC plastic hinges on the seismic performance of RC composite bridge columns, the calculation of the lateral confining stress of the ECC cover was proposed, and the fiber-element-based model with consideration of the lateral confining effect from the ECC cover was verified by a target experiment which incorporates two scaled composite columns [ 11 ] with different volume tie ratios. Then, based on the verified numerical models, a deep study was carried out.…”