Precast Segmental Piers Research Articles

Experimental study on seismic performance of post-tensioned precast segmental piers designed with multiple joint openings

In accelerated bridge construction (ABC), precast segmental piers (PSPs) have shown significant progress in shortening the construction period and reducing the cost. By combining multiple segments with post-tensioned (PT) tendons, the desired self-centering ability can be introduced; however, this may lead to a lower energy dissipation (ED) capacity and concentrated damage. To address this concern, the present study proposes a design concept that promotes multiple joint openings to achieve a better energy dissipation capacity and decentralized damage without compromising the self-centering ability. Two main approaches for this objective are discussed in detail. The first approach incorporates different arrangements of ED rebars at various joints, while the second introduces innovative damage control rubber joints (DCRJs) with varying stiffness beneath each segment. Four scaled specimens designed using these two approaches were quasi-statically tested. The observed damage, final failure mode, energy dissipation capacity, resilience index, and damage decentralization were further examined. The results revealed that for PSPs designed using the first approach, the joint openings were successfully decentralized only up to a certain level, after which they were still predominantly concentrated at a single joint, leading to strength degradation and damage concentration. PSPs designed using the second approach demonstrated decentralized joint openings, improved displacement ductility, and damage mitigation, resulting in both superior seismic and post-seismic performance.

Seismic performance of precast segmental piers with a novel combined half-grouted sleeve-socket (HGS-S) connection

This study proposes a novel connection between precast column and foundation, which combines the half-grouted sleeves and the socket-type connection and is thus termed as HGS-S. Quasi-static cyclic tests are conducted to investigate the seismic performance of this proposed connection using three 1/3.6-scale specimens, including a conventional cast-in-place one serving as reference and two precast ones using the proposed connection with different embedded depths into the foundations. The test results show that the specimens with the proposed connection are observed with sufficient integrity and emulative performance compared with their cast-in-place counterpart, indicating the efficiency and reliability of this novel connection. Furthermore, the embedded depth of grouted sleeves shows negligible influence on the structural performance, which should be further investigated and verified with more tests.

Shaking table test on seismic behavior of posttensioned precast segmental Concrete-Filled double skin steel tubular piers

Posttensioned precast segmental bridge piers have proven to be an attractive solution for accelerated bridge construction and seismic resilience. Although extensive research efforts have been made to understand the seismic performance of such piers under quasi-static loading and unidirectional/bidirectional ground motions, there is limited information available regarding to their dynamic behavior when subjected to tri-directional ground motions. Therefore, this study performed shaking table tests on an innovative posttensioned precast segmental concrete-filled double skin steel tubular (CFDST) pier to explore its seismic behavior under a set of tridirectionally applied far-field ground motions. A total of six 1/5 scaled piers were investigated with different design details, including one monolithic pier as reference, two posttensioned precast segmental piers without internal energy-dissipating (ED) bars but different amounts of prestressing tendons, and three posttensioned precast segmental piers with different amounts of ED bars. It has found that the relative displacement responses decreased with increase in amounts of prestressing tendons or ED bars. The segmental piers without ED bars twisted obviously when PGA reached 0.3 g under tri-directional ground motion excitations, while the segmental piers with ED bars did not due to additional shear resistance across joints provided by ED bars. Moreover, the dynamic responses of segmental piers with and without vertical ground motion excitation were compared in details to investigate the effect of vertical ground motion on their seismic behavior. It has found that the change in vertical acceleration response due to vertical ground motion excitation was a significant importance compared to the change in lateral accelerations, relative displacements and tendon force increment. In consequence, the axial compressive force as well as shear resistance across joint provided by dead load reduced by almost 33% due to appearance of vertical ground motion at the PGA of 0.7 g.

Experimental study on the plastic hinge region of precast segmental bridge piers strengthened by CFRP

In this study, three precast segmental pier specimens with a scale ratio of 1:5 were fabricated, and the responses of these pier specimens were studied under cyclic loading. The first reinforced concrete pier specimen (Specimen 1) had no strengthening measures or initial damage; the second pier specimen (Specimen 2) was strengthened by carbon fiber reinforced polymer (CFRP) without initial damage; finally, the third pier specimen (Specimen 3) was first tested to moderate damage, then the damaged plastic hinge region repaired by CFRP was tested for the second time. It was observed that the drift ratio, horizontal load capacity, total cumulative energy dissipation and initial stiffness of Specimen 2 were increased by 75%, 0.71%, 115% and 8.23%, respectively, compared with Specimen 1. The same performances of Specimen 3 after repairing were improved by 25%, 0.64%, 47% and 4.29%, respectively, compared with Specimen 1. Therefore, CFRP can be used for pre-seismic strengthening and post-seismic repair of precast segmental piers, providing reference for engineering application. In addition, it was found that the damage was transferred out of the strengthened region due to the confinement effect of CFRP.

Experimental and numerical investigation on hysteretic behavior of posttensioned precast segmental Concrete-filled double skin steel tubular piers

The posttensioned precast segmental concrete-filled double skin steel tubular (CFDST) piers proposed in this study combines the advantages of posttensioned precast segmental piers and composite CFDST piers, in such way to reduce on-site construction burdens, increase section modulus, and reduce self-weight. To investigate the hysteretic behavior of this new type of bridge pier, one posttensioned precast segmental CFDST pier was designed and tested under cyclic lateral loading, with one cast-in-place CFDST pier as reference. Test results show that the proposed posttensioned precast segmental pier performs well with good ductility, satisfactory energy dissipation, and small residual displacement. The damage to precast segments is effectively avoided by using CFDST members. Moreover, a numerical study was also conducted to investigate the influences of different design parameters on the hysteretic behavior of posttensioned precast segmental CFDST piers. The design parameters studied in this paper included the pier aspect ratio, amount of energy-dissipating (ED) bars, axial load ratio due to gravity, axial load ratio due to prestressing force, initial stress level in prestressing strands and CFDST cross-sectional parameters. It has been found that the amount of ED bars, axial load ratio due to gravity and axial load ratio due to prestressing force are the more important factors on energy dissipation and self-centering capacities. The pier aspect ratio being greater than 7 has a negative effect on residual drift ratio of posttensioned precast segmental CFDST piers due to P-Δ effect. The initial stress level in prestressing strands has little effect on energy dissipation and self-centering capacity, but influences the failure mode and deformation capacity.

Analysis on Load Capacity of Grouted Ducts Connected Precast Piers under Action of Bi-directional Compression and Bending

In order to improve the accuracy of the calculation method of the bearing capacity of the prefabricated pier connected by the grouting bellows, the calculation formula of the ultimate bearing capacity of assembled bridge piers with grouting corrugated pipe connection under the action of bi-directional compression and bending is deduced. Firstly, the quasi-static testing of cast-in-place piers and prefabricated piers under unidirectional and bi-directional loading are introduced, the ultimate bearing capacities are compared. Secondly, according to the arrangement position of the neutral axis and the static force balance relationship, the calculation formulas of the ultimate bearing capacity in two directions under the action of constant axial force are deduced. Finally, the calculation formulas of derivation were verified by the experimental results, and the calculated yield surfaces of the prefabricated piers with grouting corrugated pipe connection under different axial forces are established. The results show that the experimental results are relatively close to the numerical calculation results, the average error does not exceed 10%, and the P-Mx-My three-dimensional yield surface provided a relatively simple and quick method for the cross-sectional safety verification of precast segmental piers with Grouting Corrugated Pipe Connection.

Improving seismic behaviors of precast segmental piers with bonded prestressed tendons

Precast segmental bridge piers attract engineers due to the strengths of accelerated construction, reduced traffic disturbance and enhanced quality control. However, their widely applications in high-seismicity areas are hindered, for the insufficient capacities of energy dissipation. In this study, precast segmental piers’ seismic behaviors were investigated, focusing on the connection of ‘grouted sleeves/bonded tendons’. To this end, four piers were cyclically loaded, of one cast-in-place pier, one precast segmental pier, and two prestressed precast segmental piers. Among them, Benefits of bonded tendons were evidenced, in terms of lateral strength, ductility, energy dissipation capacity and residual drift. Of particular, bonded tendons prevented the shear-induced slip between the shaft and footing segments. Enlightened from observations, cyclic dowel-friction effect is proposed and implemented within a zero-thickness sliding spring in the finite element model, capable of capturing the shear-induced joint slip. Furthermore, seismic vulnerability assessments of the bridge piers are obtained in terms of fragility curves, by performing incremental dynamic analyses. In addition, the effects of bonded or unbounded tendons are also discussed. Two criteria are adopted to define the limit states, namely displacement ductility and residual drift. It is suggested that bonded tendons could significantly ameliorate the fragility curves of precast segmental piers. HIGHLIGHTS Four bridge piers were cyclically loaded, with various prestressing levels. A reliable fiber-based model was constructed, considering shear-induced slip at the segmental joint for the first time. Seismic vulnerability assessments were performed to quantify the piers’ behaviors.

Experimental study on the behavior of precast segmental piers under ship impact loading

This paper is to study the difference of anti-collision performance between precast segmental piers and conventional monolithic reinforced concrete (RC) piers. A reduced scale model was used, and the dynamic responses of piers with different structures under impact were compared and analyzed. The nonlinear finite element (FE) model of pier impact was established and numerical simulation of the impact responses and the failure mode of piers was carried out. The research results indicated that under impact, the failure mode of monolithic pier is tension bending failure, and for the segmental piers, the shear slip and concrete crushing in the impact segment occur mainly. The test results also indicated that the segmental piers are more flexible than monolithic piers, which leads to the peak impact force of the segmental pier reduced by 21.25% and 6.55%, respectively, under the impact of rigid head and ship bow compared to that on the monolithic pier. The study also found that segmented piers have better deformation capability and less residual displacement, but fail to show good self-reset capability. The results of FE calculation match well with the test results, which verifies the applicability and reliability of the FE model used in this paper.

Precast segmental piers: testing, modeling and seismic assessment of an emulative connection based on a grouted central tenon

Precast segmental piers: testing, modeling and seismic assessment of an emulative connection based on a grouted central tenon

Three-dimensional finite element analyses for cyclic responses of precast segmental bridge piers accounting for bond-slip degradation

Precast segmental piers are attracting the bridge community due to the merits of faster construction speed, smaller site disruption and higher construction quality. Compared to numerous experimental studies, accurate finite element (FE) models to investigate seismic responses of precast piers are rather rare. Among them, an apparent insufficiency is ignorance or inappropriate treatment of bond behavior. To this end, a zero-thickness interface element is adapted between 1 D truss element (rebars) and solid element (concrete). The bond behavior is implemented within the interface element, especially the strength degradation subject to cyclic loading, which renders simulations more realistic. The models further incorporate the softened damage-plasticity model for concrete and Menegotto-Pinto model for rebars. Viscous regularization scheme is adopted to circumvent the convergence difficulty brought out by the strain softening. The 3 D FE models are validated by the experimental works recently performed by authors. All analyses are performed on Abaqus/Standard platform, with the implicit incremental-iterative Newton-Raphson algorithm. The source code (UEL subroutine) is disclosed on github to faciliate relevant researches.

Experimental and numerical investigations on cyclic behaviors of precast segmental bridge piers with the hybrid of high-strength bars and unbonded prestressing tendons

Precast segmental piers are gaining increasing attentions in low-medium seismic-risked regions. In this paper, cyclic behaviors of two precast segment piers reinforced with the hybrid of high-strength energy dissipation (“H” ED, ≥500 MPa) bars and unbonded tendons were experimentally investigated, accompanied with another two piers reinforced with merely “H” ED bars for the comparative study. It was observed that unbonded tendons benefitted the segmental piers in rising the lateral strength and mitigating the residual drift. On the other aspect, the tendons also made concrete prone to damage. Alongside, the finite element (FE) model is constructed for the four tested segmental piers, discritized with the displacement-controlled beam-colum element with a fiber section. With the bond-slip behavior of the “H” ED bars being incorporated, the numerical model accurately reflects the piers’ seismic behaviors.

Axial compression ratio limit for self‐centering precast segmental hollow piers

Axial compression ratio limit was investigated for self‐centering precast segmental hollow piers based on post‐earthquake residual axial loading capacity. The analytical method of unbonded posttensioning tendons (PT) stress increment and the simplified method of compression zone height were developed and validated by the finite element model verified by experiments. An analytical formula was deduced to calculate the critical axial compression ratio, which was regarded as the limit and can be obtained when the capacity provided by the noncompression zone at the bottom is equal to the initial axial compression loading. Parameter analysis was conducted to study effects of eight common design parameters on the critical axial compression ratio. The conclusions are summarized that there is good accuracy between the proposed methods for both unbonded PT stress increment and compression zone height and the finite element analysis. The axial compression ratio limit is proposed to be 0.25 when the ratio of energy dissipation (ED) bars is <1.5%. It is an inadvisable solution that more ED bars are matched with higher initial tensioning force of unbonded PT to fulfill the precast segmental piers with good ED capacity and self‐centering capacity in practice.

Full-scale test of the hydration heat and the curing method of the wet joints of a precast segmental pier of a bridge

Although prefabricated segmental structures, especially for use as a sea-crossing bridge, exhibit high quality and are barely affected by the environment and climate, more attention should be paid to the wet joints to ensure the durability of such structures (e.g. a precast segmental pier). Using one offshore bridge as a reference, this study reports the results of full-scale model tests performed to determine the factors of the hydration heat, with focus on two types of concretes integrated using different curing methods. The wet joint concrete admixed using an expansive admixture and a painting compound curing method proved to be satisfactory and thus recommended for use on the reference bridge. Inspections for over five years of the reference bridge proved that the results were better than expected.

Experiments on flexural strength on composite modular bridge pier cap for CFT columns

Modular bridge substructures consisting with Concrete-Filled steel Tube (CFT) columns, composite precast segments have been suggested to accelerate bridge construction. The precast segmental pier cap consists of a composite pier table and prestressed precast concrete segments on the table. The pier table has embedded steel sections to mitigate stress concentration at the connection between concrete pier cap and small steel tubes. The shear strength of the pier cap was obtained by extending vertical reinforcing bars from the table to the precast segment. Transverse prestressing was introduced to control tensile stresses of the segments with service loadings. Structural performance of the proposed modular system was evaluated by static tests. Test results showed that the horizontal shear force from the vertical load should be resisted by bond, friction and vertical reinforcements crossing the interface. When the anchorage of vertical reinforcements and preventing of premature fracture of prestressing steels were provided, the flexural strength of the pier cap module at the joint location showed reasonable prediction.

Cyclic Load Tests on Self-Centering Concrete Pier with External Dissipators and Enhanced Durability

AbstractA precast segmental pier using posttensioning technique has become a desirable candidate to realize rapid, environment-friendly bridge construction and minimal residual deformation. To avoid structural corrosion and to facilitate the replacement of energy dissipators (EDs), a self-centering precast concrete (SCPC) pier with external EDs and enhanced durability is proposed and experimentally evaluated. In this study, the self-centering capacity is provided through posttensioned basalt fiber–reinforced polymer (BFRP) tendons, and the bottom of the pier is encased in a glass fiber–reinforced polymer (GFRP) jacket so as to mitigate concrete spalling or crushing as the pier rocks. Aluminum bars with modified material properties are used as external EDs, in which the weakened part is filled in a confining tube with epoxy. Fifteen cyclic load tests with the maximum drift of 4% were conducted on three SCPC piers and one monolithic pier, and the influence of various design parameters on the pier behavior i...

프리캐스트 모듈러 피어캡의 구조성능 평가

Prefabrication technologies are making bridge construction safer and less disruptive to the environment and traveling public, making bridge designs more constructible and, improving the quality and durability by shifting site work to a more controllable environment. Modular bridge substructures with concrete-filled steel tube (CFT) piers and composite pier caps were suggested to realize accelerated bridge construction. The precast segmental pier cap consists of a composite pier table and precast prestressed segments on the table. The pier table has embedded steel section to mitigate stress concentration at the connection by small tubes. Each bridge pier has four or six CFT columns which connect to the pier cap. Shear strength of the pier cap was obtained by extending vertical reinforcing bars from the table to the precast segment. Transverse prestressing was introduced to control tensile stresses by service loadings. Structural performance of the proposed modular system was evaluated by static tests. Design requirements of the composite pier cap were satisfied by continuous reinforcing bars and prestressing tendons. Standardized modular substructures can be effectively utilized for the fast replacement or construction of bridges.

Seismic performance of precast hollow bridge piers with different construction details

Currently the design scheme of precast hollow concrete bridge piers will be adopted in bridge design in China, but there is no code including specific design details of precast segmental piers in high seismic risk area. For comparative study of seismic performance of the hollow bridge piers which had different design details, six specimens of hollow section bridge pier were designed and tested. The specimens consist of the monolithic cast-in-place concrete bridge pier, precast segmental prestressed pier with cast-in-place joint and precast segmental concrete bridge pier with dry joints. Results show that all specimens have good displacement capacity. The bridge pier with bonded prestressed strands exhibits better energy dissipation capacity and higher strength. The un-bonded prestressed strand bridge pier displays less residual plastic displacement and energy dissipation capacity. The bridge pier with both bonded prestressed strands at the edge of the section and un-bonded in the center of the section not only exhibits more ductility capacity and less residual plastic displacement, but also shows better energy dissipation capacity. Compared with experimental results of prestressed bridge columns, analytical result demonstrates the developed numerical analysis model would provide the reasonable and accurate results.

Seismic Performance Analysis of a Continuous Girder Bridge with Precast Segmental Pier

Based on available research results of precast segmental bridge pier, seismic performance of a continuous girder bridge with precast segmental bridge columns using match-cast dry joints was analyzed with the lumped plastic hinge method verified by experiment, the similarities and differences of seismic performance between the continuous girder bridge with precast segmental bridge columns and that of cast-in-placement reinforced concrete bridge columns were gained. Results show that the maximum displacement response of the continuous girder bridge with precast segmental bridge columns is bigger than that of the continuous girder bridge with cast-in-place reinforced concrete bridge columns. While for the residual displacement, the opposite is true. The reason is that the restoring force exists in the precast segmental bridge pier by the prestress strands. The concentrated plastic hinge method for cast-in-place reinforced concrete bridges could be used to bridges with precast segmental bridge columns.