Novel post‐tensioned rocking piles for enhancing the seismic resilience of bridges

Abstract

The rocking pile foundation system is a relatively new design concept that can be implemented in bridges to improve their seismic performance. This type of foundation prevents plastic damage at the bridge piers and the foundation system, which are difficult to repair and can lead to collapse. However, lack of adequate energy dissipation in this type of foundation can result in large deck displacements and subsequent catastrophic failures of the bridge. The present study proposes a novel foundation system that integrates post-tensioned piles with the rocking foundation to simultaneously prevent plastic hinging at the piers and reduce the deck displacements during severe earthquakes. The effectiveness of the proposed foundation system is investigated and compared against the rocking pile and conventional fixed-base foundation systems using identical bridge configurations. Three-dimensional finite element models of these bridges were developed to capture possible nonlinear behavior of the bridge as well as soil-structure interaction effects. Six strong earthquakes with both horizontal components were selected and scaled to the appropriate seismic hazard level with a return period of 2475 years. Static pushover and nonlinear time-history analyses were then performed to compare the dynamic response of the bridges, including deck displacements, pier and pile inertial forces, and other nonlinear behavior experienced by the structure. The results reveal that by integrating the post-tensioned piles with the rocking foundation, the deck displacements were reduced to an acceptable limit without subjecting the bridge to any damage. In contrast, the bridge with the fixed base foundation experienced extensive damage at the piers, and the bridge with the rocking foundation experienced substantial deck displacements that ultimately led to unseating, resulting in the collapse of both bridges. It was therefore concluded that the proposed rocking foundation system with post-tensioned piles is the superior alternative and can be implemented in practice as an attractive solution due to the seismic protection it offers.

3D response simulation of a bridge with a posttensioned base rocking steel pier under sequential loading of traffic loads, braking force, and earthquake excitations

“…Various techniques have been studied to minimize such damage. [19][20][21][22][23][24] More recently, the rocking concept has been adapted to steel piers. The PT base rocking steel pier comprises a circular steel tube, circular end plates, PT tendon(s), and supplemental energy dissipation devices.…”

“…Most of these investigations were conducted on reinforced concrete columns, 15–18 which might incur damage at the rocking interface due to generation of high compressive stresses and lose their ability to recentre. Various techniques have been studied to minimize such damage 19–24 …”

Experimental study of a scaled bridge model with a unidirectional rocking isolation bearing system (Uni‐RIBS) through shaking table tests

“…However, recent earthquake damage reports highlight the need to prevent compromised functionality and serviceability, particularly critical for post‐disaster rescue and recovery, even when seismic events exceed the current design threshold. To address this, innovative structural systems incorporating resilient features (e.g., self‐centering and replaceable components) have garnered global research interest in recent years 1–3 …”

“…To address this, innovative structural systems incorporating resilient features (e.g., self-centering and replaceable components) have garnered global research interest in recent years. [1][2][3] Similar concepts are actively discussed within the civil engineering community, especially considering the imminent threat of severe earthquakes in Japan (e.g., Nankai megathrust earthquakes and great earthquakes right under the capital). Achieving next-generation seismic structures hinges on their ability to withstand beyond-design-basis events (BDBEs) and maintain their designated function, performance, and operational capacity, referred to as anti-catastrophe.…”

Review on seismic resilient bridge structures

“…Seismic resilience design concept of bridge structures Bruneau et al (2003) first proposed the concept of structural seismic resilience design, and the seismic resilience structures cannot collapse and can be restored its function by no repair or minor repair after the earthquake. At present, bridge structures are as the important part of lifeline engineering, the realization of seismic resilient bridge structures has been recognized by the international earthquake engineering community and has become a research hotspot (El-Hawat et al, 2022;Han et al, 2021a;Lv et al, 2019;Lv and Chen, 2014;Zhang et al, 2019a;Zhou et al, 2019a).…”