Parametric Investigation of Bridge Piers Reinforced with Shape-Memory Alloys in Plastic Hinge Regions

The conventional design philosophy of bridges allows damage in the pier through yielding. A fuse-like action is achieved if the bridge piers are designed to develop substantial inelastic deformations when subjected to earthquake excitations. Such a design can avoid collapse of the bridge but not damage. The damage is the plastic hinge formation formed at location of maximum moments and stresses that can lead to permanent lateral displacement which can impair traffic flow and cause time consuming repairs. Rocking can act as a form of isolation by means of foundation uplifting which act as a mechanical fuse, limiting the forces transferred to the base of the structure. In this context, this paper proposes a novel resilient controlled rocking bridge pier foundation, which uses elastomeric pads incorporated beneath the footing of the bridge piers and external restrainer in the form of shape memory alloy bar (SMA). The rocking mechanism is achieved by restricting the horizontal movement of footing by providing stoppers at all sides of footing. The pads are designed to remain elastic without allowing their shearing. The pier, the footing and the elastomeric pads are assumed to be supported on firm rigid concrete sub base resting on hard rock. By performing nonlinear dynamic time history analysis in the traffic direction of the bridge, the proposed pier with the novel resilient foundation is compared against a fixed-based pier and classical rocking pier (CC). The proposed pier rocking on elastomeric pads and external restrainer (CP+SMA) has good re-centering capability during earthquakes with negligible residual drift and footing uplift. In this new rocking isolation technique, the forces in the piers are also reduced and thus leading to reduced construction cost with enhanced post-earthquake serviceability.

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Estimating the plastic hinge length of rectangular concrete columns reinforced with NiTi superelastic shape memory alloys

Engineering Structures ◽

10.1016/j.engstruct.2021.113641 ◽

2022 ◽

Vol 252 ◽

pp. 113641

Author(s):

Chang Seok Lee ◽

Eunsoo Choi ◽

Jong-Su Jeon

Keyword(s):

Shape Memory Alloys ◽

Shape Memory ◽

Plastic Hinge ◽

Concrete Columns ◽

Plastic Hinge Length

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Analytical Seismic Fragility Curves for Reinforced Concrete Wall pier using Shape Memory Alloys considering maximum drift

MATEC Web of Conferences ◽

10.1051/matecconf/201925804001 ◽

2019 ◽

Vol 258 ◽

pp. 04001 ◽

Cited By ~ 1

Author(s):

Nursafarina Ahmad ◽

Azmi Ibrahim ◽

Shahria Alam

Keyword(s):

Reinforced Concrete ◽

Shape Memory Alloys ◽

Shape Memory ◽

Seismic Performance ◽

Fragility Curves ◽

Plastic Hinge ◽

Bridge Pier ◽

Seismic Fragility ◽

Demand Model ◽

Promising Alternative

Fragility curves express the seismic vulnerability of bridge piers for different damage states at various earthquake intensities. A fragility curve typically gives a physical understanding of repair costs and functionally levels of a bridge pier. Shape memory alloys (SMAs) provide a promising alternative material in reducing the failure probability of a bridge pier. This study develops a family of seismic fragility curves for reinforced concrete (RC) wall piers reinforced with three different types of SMA rebar in plastic hinge regions. An incremental dynamic analysis (IDA) using a total of 20 earthquake ground motions was performed on a SMA-RC wall pier to evaluate its seismic performance. The maximum drift recorded for each ground motion was taken as the seismic performance demand parameter of interest in this study. The probabilistic seismic demand model (PSDM) was used to generate fragility curves for each RC-SMA wall pier. The results show that the different mechanical properties and type of SMAs affect the performance of RC-SMA wall pier.

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