Post-tensioned Research Articles

Nonlinear Behavior of Bonded and Unbonded Two-Way Post-Tensioned Slabs Pre-Strengthened with CFRP Laminates

In this study, hybrid nonlinear finite element models (FEM) were developed to examine the flexural performance and the ultimate load capacity of bonded and unbonded two-way reinforced concrete post-tensioned (PT) slabs that were pre-strengthened with external carbon-fiber reinforcement polymer (CFRP) laminates. Full 3D simulations, using ANSYS models, have been created for five different slab samples that were selected from a previously available experimental study. The model results were assessed to enable further numerical analysis. The result calibration included measurements of first crack loads, ultimate loads, deflections, strains in the extreme fiber of concrete, strains in CFRP laminates, and failure modes. The results proved a good correlation between FEM output and experimental ones. Based on this, the influencing parameters that affect plate stiffness, as well as the bending capacity of PT slabs, were examined by performing a detailed parametric study. The parameters included real-life load simulation, cable-to-CFRP strength contribution, and CFRP laminate location selection. The results demonstrated that strengthening using CFRP laminates have significantly increased the ductility index of both bonded and unbonded PT concrete slabs by 62.18% and 59.87%, respectively. In addition, strip strengthening locations near supports are much more effective than in the middle of slabs. Additionally, the CFRP strengthening contribution is very considerable in slabs with low PT ratios.

The Sliding Keys on Inclined Deflecting‐cantilevers (SKID) device: Empirical and analytical sensitivity analysis with application in post‐tensioned frames

AbstractPreviously, the authors presented a new theoretical energy dissipating technology termed a Frictional Sliding on a Sprung Slope (FSSS) device. Its purpose was to provide significant energy dissipation to post‐tensioned (PT) frames structures. The FSSS device has a triangular‐shaped hysteretic curve, which has a zero‐force activation threshold. This enables activation for any earthquake magnitude and provides progressively greater energy dissipation with an increase in structural oscillations. In addition, it is designed to allow full self‐centring of the PT framed structure. In this paper, a physical prototype FSSS is designed, constructed and experimentally tested. The prototype replaces the theoretical springs, bearings and the constraints with pairs of cantilever bars. Consequently, it is renamed a Sliding Keys on Inclined Deflecting‐cantilever (SKID) device. Six scaled SKID configurations having different manufacturing parameters were built and tested. Also, five materials were used to investigate the sensitivity to the friction coefficient of the sliding pads. Both cyclic and fatigue tests were conducted to assess SKID performance empirically. A finite element model of SKID was then implemented in OpenSees and benchmarked against the experimental results. More than 700 one‐story one‐bay PT frames with different SKID devices (PT‐SKID frames) were numerically tested to investigate the dynamic characteristics of the structural system affecting the seismic response. Based on the extensive experimental and numerical analyses, design suggestions are provided, and the PT‐SKID self‐centring features are discussed.

Experimental study on a dry-assembled precast concrete frame with buckling-restrained braces

This paper proposes a new dry-assembled precast concrete frame with buckling-restrained braces (BRB-DPCF) to reach the full potential of building industrialization and promote the popularization of precast structures in earthquake-prone zones. A new mechanical coupler and an unbonded posttensioning (PT) technology were adopted for the column-to-column joint and beam-to-column joint, respectively, of the BRB-DPCF. In this paper, the authors designed and tested a monolithic concrete frame with buckling-restrained braces (BRB-MCF) and a BRB-DPCF to investigate the seismic performance of the BRB-DPCF. The two specimens were two-story, single-bay concrete frames with a story height of 1750 mm and a bay of 2500 mm. The test results demonstrated that the BRB-DPCF exhibited stable and fat hysteretic loops and a lateral-resistance capacity comparable to the BRB-MCF. The BRB-DPCF showed a greater initial stiffness and smaller energy dissipation capacity than the BRB-MCF. The column damage of the BRB-DPCF was similar to that of the BRB-MCF, while the girder damage of the BRB-DPCF was negligible compared with that of the BRB-MCF. The BRB-DPCF featured a greater repairable ability after earthquake events than the BRB-MCF.

Parametric Study on Steel–Concrete Composite Beams Strengthened with Post-Tensioned CFRP Tendons

A sustainable environment can be achieved by strengthening the existing building to avoid new construction and by replacing the construction materials with long-lasting sustainable materials such as a fiber-reinforced polymer (FRP). Using post-tensioned (PT) FRP systems has proven to be an effective technique in strengthening the structure and decreasing cracks and deformability. In this study, a 3-D finite element model was built to investigate the flexural behavior of composite beams strengthened with external PT FRP tendons. Limited research studied the use of FRP tendons to enhance the structural behavior of composite beams. This paper represents a comprehensive study of the effect of several parameters that control the design of the FRP tendons. Parameters such as PT level, tendon material, tendon length, degree of shear connection (DOSC), and tendon profile shape were considered under loading. The 3-D model’s correctness is validated using published experimental data. It was observed that of all FRP materials, carbon FRP is the best type for upgrading the beam strength, and it was recommended to use a 30 to 40% PT level. In addition, applying external PT over the full length of the beam increases the ultimate load capacity significantly. However, due to the difficulty of construction, it was recommended to use 90% of the beam span length since the difference in beam capacity does not exceed 5%. Finally, adding PT tendons with a trapezoidal and parabola profile to composite beams significantly increases the yield load and the beam capacity.

Experimental investigation of a locally-compressed beam-column connection with bar-typed fuses

To promote the development and application of a self-centering (SC) frame structure, a novel reinforced concrete SC frame (SPTF) with short and curved posttensioned (PT) strands is proposed and experimentally explored in this paper. The PT strands are internally mounted across the column and beam components and anchored at the beam sides to locally compress the joint components together. An all-steel and replaceable damper, which is referred to as the miniature bar-typed structural fuse (MBSF) is utilized as the energy dissipation component. Two full-scale interior frame joints were fabricated and subjected to 5 independent reversed cyclic loading tests. Structural performances, including the damage modes, hysteretic behaviors, strength and stiffness degradation, and PT forces of the specimens are discussed. Consequently, the SPTF specimen showed favourable seismic performances and SC behaviours. A mechanical analysis principal model modified according to the experimental results, which shows adequate accuracy, is correspondingly demonstrated.

A novel seismic energy dissipating device, Sliding Keys on Inclined Deflecting-cantilevers (SKID): Theoretical and experimental evidence

An innovative physical realisation of the previously reported conceptual frictional sliding on a sprung slope (FSSS) device is proposed in this paper. The device uses the end stiffness of cantilevers as the “sprung-slope”, which generate amplitude varying normal and frictional forces along the sliding plane. This novel configuration is here termed a Sliding Keys on Inclined Deflecting-cantilevers (SKID) device. The SKID device is proposed for application with post-tensioned (PT) frames to improve lateral stiffness and energy dissipation capability without inhibiting their self-centring features. The configuration and theoretical properties of the device are presented. In particular, the reliability of using cantilever bars as a means of generating an amplitude-dependent normal force at the sliding surfaces is discussed. Then, two 1/4 scale-reduced prototypes, which have (i) negative unloading stiffness (SKID A) and (ii) positive unloading stiffness (SKID B), were designed and manufactured. Both specimens were subjected to the same quasi-static cyclic loading protocol. It was found that they exhibited stable and repeatable triangular-shaped hysteretic curves. The theoretical hysteretic load/deflection envelopes are compared with test specimen results, verifying a satisfactory consistency between the theoretical and physical SKID device.

Experimental investigation of a locally prestressed precast concrete wall

AbstractThe posttensioned (PT) tendons in a prestressed precast wall (PPW) may suffer yielding or damage under rare earthquake events, increasing the potential demand for their maintenance and renewal. A locally PPW (LPPW) with PT tendons arranged only in the lower stories was developed in this article to facilitate the replacement of the PT tendons. Quasi‐static tests were conducted to investigate the seismic performance of the LPPW with and without additional energy dissipaters. The test results demonstrated that the LPPW featured a stable hysteretic response and an excellent self‐centering capacity. The dissipaters effectively improved the energy dissipation capacity of the LPPW and preserved its self‐centering capacity. Numerical studies were further performed to address the influence of the layout of the PT tendons and dissipaters. The numerical results showed that reducing the height of the upper anchorage points of the PT tendons could increase the bearing capacity and postyielding stiffness of the LPPW. The concrete contact force at the base joint could be reduced by about 40% by moving the dissipaters from center to edge regions of the cross‐section of the wall.

Parametric experimental investigation of unbonded post‐tensioned reinforced concrete bridge piers under cyclic loading

AbstractThe present paper investigates the cyclic performance of unbonded post‐tensioned reinforced concrete (PRC) rocking piers by a parametric experimental campaign. PRC rocking specimens are assembled by hybrid connections, containing an ungrouted post‐tensioned (PT) bar and grouted mild steel bars, that is, energy‐dissipation (ED) components. The properties of a benchmark PRC pier were defined according to a design procedure to control its strength, ductility, energy dissipation capacity, and self‐centering behavior. Five additional PRC piers with different ED bars amounts, initial PT force, and ED bars unbonded lengths were also tested to investigate the influence of these parameters on the cyclic performance. The test results show the superior cyclic performance of the PRC pier in limiting both damage and residual deformations. The parametric analysis highlighted that decreasing the initial PT force and/or ED bars amount enhances the PRC's ED capacity at the expense of the lateral force resistance and self‐centering behavior. Moreover, it has been observed that the influence of ED bars’ unbonded length only minimally affects the PRC pier's cyclic performance due to ED bars’ bond‐slip and concrete cover spalling of the pier shaft. Analytical models describing the PRC piers’ lateral force‐drift cyclic behavior were formulated and calibrated, showing a good agreement with test results for all specimens. The results and findings provide a valuable reference and solution for tailoring an efficient parameter recommendation of PRC rocking piers.

Finite-Element Simulation of the Lateral Response of Posttensioned Base Rocking Steel Bridge Piers

This paper presents the results of a finite-element (FE) study on posttensioned (PT) rocking steel bridge piers, each composed of a circular tubular column, welded end plates, PT strands, and axially yielding steel energy dissipators (EDs), and corresponding chairs. The pier is configured so that it rocks at its base. Previously conducted experiments on five scaled rocking steel columns are summarized. Three-dimensional (3D) continuum FE models of the tested specimens are generated with the objective of verifying the capability of the modeling approach in the simulation of the local and global responses. Strain-controlled cyclic coupon tests were performed to quantify the kinematic and isotropic hardening material parameters. A simplified method is proposed to model the cyclic loss of prestressing because of wedge seating in a typical industry monostrand anchorage system. The FE procedure is then calibrated against the experimental data at the material, component, and global pier levels. A parametric study is conducted to examine the effects of key factors such as material model, P-Delta, base plate dimensions, column diameter-to-thickness and initial axial force ratios, ED chairs, and ED location on the lateral cyclic response. It is demonstrated that, for a given target drift, local buckling and the resulting residual lateral deformations of a rocking steel pier are a function of the diameter-to-thickness and initial axial force ratios of the column and the ED chairs. By the proper selection of these variables, a stable and robust self-centering response can be obtained with minimal damage to the bridge pier.

A Unified Equation for Prediction of Concrete Strength at Various Ages Using the Ultrasonic Pulse Velocity

Using ultrasonic pulse velocity (UPV) testing has long been regarded as an effective approach for evaluating concrete strength; however, because of the influence of numerous factors (e.g., mixture proportion, type of coarse aggregate, pozzolanic admixture, and age of the concrete), the relationship between UPV and concrete strength cannot be conclusively determined, thus hindering the application of this approach. The objective of this paper is to develop a unified equation for prediction of concrete strength at various ages using the ultrasonic pulse velocity. Firstly, this study investigated the relationship between the UPV evolution index and the strength evolution index of normal concrete with various mixture proportions, coarse aggregate types, and ages. Subsequently, the influence of adding pozzolanic materials on this relationship was considered. The experimental results showed that excellent correlation between the UPV evolution index and the strength evolution index was found and a unified equation was established in this study through regression analysis to represent the relationship between the UPV and the strength evolution index. Finally, the applicability of the unified equation was verified by data obtained from different studies. The results indicated that for all concrete specimens more than 3 days old, the error of the strength estimation decreased to within ±15%, demonstrating that this unified equation has substantial value for application in decision-making processes for major construction procedures (e.g., applying post tensioning or removing formwork supports).

Explainable machine learning based efficient prediction tool for lateral cyclic response of post-tensioned base rocking steel bridge piers

This study presents a novel explainable machine learning (ML) based predictive model for the lateral cyclic response of post-tensioned (PT) base rocking steel bridge piers. The PT rocking steel bridge pier comprises a circular tube with welded circular base plate that is pre-compressed to its base by means of gravity loads and/or a PT tendon. The input factors were column diameter, column diameter-to-thickness ratio, column height-to-diameter ratio, cross-sectional area of tendon-to-column ratio, tendon initial post-tensioning ratio, dead load ratio, base plate thickness, and base plate extension. Response variables were column residual drift, column shortening, ratio of degraded stiffness to initial stiffness, maximum lateral strength to uplift force ratio, and lateral strength reduction ratio. Nine ML techniques that range from the simplest to advanced techniques were used to generate the predictive models. Several statistical performance indices are computed for the evaluation of the models. The results showed that the simplest white-box models are inadequate to capture the relationship between the input factors and the response variables. The comparative analysis of the examined models showed the superior prediction performance of the proposed xgBoost based model with a maximum coefficient of determination, agreement index, Kling-Gupta efficiency, and lowest error. The results also demonstrated that the optimized xgBoost model can be used to predict the lateral cyclic response of the rocking steel bridge piers efficiently and accurately. In addition, the unified model agnostic Shapley Additive exPlanation (SHAP) framework was employed to explain the outputs of xgBoost model and analyze the significance of the factors and their interaction on the predicted response quantities. Finally, the optimized best predictive model is used to develop a simple and user-friendly web-based prediction tool that facilitates the rapid and efficient lateral cyclic response prediction of post-tensioned base rocking steel bridge piers.

Fragility-informed seismic design of multi-column bridge bents with post-tensioned concrete columns for accelerated bridge construction

Accelerated Bridge Construction (ABC) is playing an increasingly large role in bridge construction within urban centers due to faster installation, improved quality and lower cost. Concrete columns are prefabricated and connected together with footings and cap beams using either grouted splice sleeves, socket connections, or through post-tensioning. Precast unbonded post-tensioned (PT) concrete columns are protected from damage due to their ability to mitigate seismic demand through rocking. A numerical model is developed for rocking columns which is validated using published data. Seismic assessment of a two-column bridge bent constructed with precast PT concrete columns is carried out; column height-to-width ratio and ratio of initial posttensioning force to axial column capacity are selected as the assessment parameters. Performance limits are defined for the bridge model using non-linear pushover analysis. Probabilistic seismic hazard analysis is carried out using nonlinear time-history analysis for a set of eighty ground motions. The results show that PT concrete columns provide sufficient re-centering to the bridge bent so that it remains serviceable after a large earthquake. An ABC bridge bent with unbonded PT concrete columns is designed using the outcome of seismic fragility analysis. The seismic performance of the fragility-designed PT bridge bent is compared to that of a bent with conventional cast-in-place (CIP) concrete columns using nonlinear time-history analysis. The seismic performance of the ABC PT bridge bent using fragility analysis satisfied performance objectives similar to a monolithic CIP bent designed according to the latest seismic design codes; in addition, the residual drift of the PT bent was practically zero. The fragility-informed approach for designing ABC bridge bents constructed with unbonded PT concrete columns presented is expected to promote post-earthquake serviceability and functional recovery after a large earthquake.

Experimental study on a self-centering RCS interior joint endowed with replaceable dampers

Reinforced concrete column and steel beam (RCS) joints are typically designed to dissipate seismic energy by the inelastic deformation of plastic hinges developed at beam ends. This design results in difficult-to-repair damage and residual drifts. In this paper, as a result, a self-centering RCS interior joint with dampers that can be easily replaced and unbonded post-tensioning (PT) strands fixed at the middle of the steel beam is proposed. The aforementioned joint is thus expected to substantially decrease residual drift under strong earthquakes. A quasi-static experimental program on nine self-centering RCS interior joints was carried out. The experiments explored the feasibility of the self-centering RCS interior joint and tested its mechanical and hysteretic behavior, energy dissipation capabilities, self-centering capabilities and replaceability of the proposed joint. The experimental results clearly showed that the proposed joint experienced minimal residual drift and performed satisfactorily in terms of moment carrying capacity and energy dissipation capabilities. Moreover, the self-centering ratio λ considerably affected the seismic behaviors of the joint. Finally, the specimens performed almost identically after the replacement of damaged dampers.

Quantifying Effect of Post-Tensioned Bars for Precast Concrete Shear Walls

A hybrid concrete wall is made up of a traditional reinforced concrete wall with post-tensioned technology. Recent research has shown that post-tensioned (PT) reinforced concrete shear walls have a wide range of advantages when it comes to resisting lateral forces and lateral moments caused by earthquake loading. To explore the PT reinforced concrete wall behavior subjected to seismic load, the concrete models were augmented with various material models, including the KCC, CDP, and Winfrith models for a PT 2D wall under pushover analysis. To ensure that the overall behavior forecast was qualitatively acceptable, the models’ performance was compared to experimental findings. Then, the post-tensioned modeling approach was implemented with the 3D wall in order to predict structural responses of the PT 3D wall. The well-validated finite element models were ultilized to estimate the effects of the post-tensioned bars on lateral resisting capacities of the precast concrete shear wall.

Self-centering rocking dual-core braced frames with buckling-restrained fuses

This paper proposes a self-centering rocking dual-core braced frame system with buckling-restrained fuses (SC-RDC-BRF). While providing low-damage design and improved seismic resilience, the proposed system prevents soft-story failure in steel braced frames. The use of buckling-restrained fuses and post-tensioned (PT) cables in the SC-RDC-BRF system enables the structure to dissipate energy and exhibit self-centering behavior effectively. The proposed rocking system does not require column uplifting and thus preventing demand amplifications on the frame members. The paper also develops a design method for SC-RDC-BRF systems. The design method is based on a preliminary design with a rigid core assumption and a modified response spectrum analysis for the design of the rocking cores (i.e., beams, columns, braces, and ties). Nonlinear static and dynamic analyses are also performed on three-, six-, and nine-story frames to verify and illustrate the design method. Results from nonlinear response history analyses confirm the adequacy of the proposed design method and expected performance of SC-RDC-BRF systems.

Experimental study on the seismic performance of a prefabricated steel column-column connection

An innovative prefabricated steel column-column connection composed of upper column, lower column, angles, friction device and posttensioned (PT) strands was proposed, in which seismic performance was mainly studied and theoretical analysis was carried out. This paper analyzed the influence of the axial compression ratio, the presence or absence of angle, and the thickness of angle on the failure model, hysteresis curves, skeleton curves, displacement ductility ratio and energy dissipation ability of the specimens. The test results demonstrated that initial stiffness and energy dissipation ability of the specimen increased by 15.1% and 8.6%, respectively, with an increase in the axial compression ratio by 0.11. The load-carrying capacity of the specimen with a 6 mm angle was always greater than that of the specimen without angle under the same loading displacement. The peak load and final cumulative energy dissipation of the specimen with a 6 mm angle increased by 16.3% and 28.7%, respectively, compared to that of the specimen without an angle. Increasing the thickness of the angle could effectively promote the load-carrying capacity and slow the later stiffness degradation and decrease the bucking deformation degree on the lower column flange of the specimen. However, when the thickness of angle is from 0 mm to 6 mm, from 6 mm to 10 mm, from 10 mm to 14 mm, the displacement ductility ratios of specimen is reduced by 21.8%, 11.7% and 39.8% respectively. In addition, an analytical bending capacity model of the connections was developed, which could reasonably predict the load-carrying capacity of the connections.

Reliability analysis of deteriorated post-tensioned concrete bridges: The case study of Ynys-y-Gwas bridge in UK

Concrete structures are exposed to aggressive environmental conditions that lead to corrosion of the embedded reinforcement and pre-stressing steel. Consequently, the safety of concrete structures may be compromised, and this requires a significant budgets to repair and maintain critical infrastructure. Prediction of structural safety can lead to significant reductions in maintenance costs by maximising the impact of investments. The aim of this paper is to establish a framework to assess the reliability of existing post-tensioned concrete bridges. A time-dependent reliability analysis of an existing post-tensioned involving the assessment of Ynys-y-Gwas bridge has been presented in this study. The main cause of failure of this bridge was corrosion of tendons, making it a relevant case study to evaluate the effect of corrosion on bridge safety. Uncertainties associated with material properties, geometry, loads and corrosion parameters are taken into account. The probabilistic models of the uncertainties are combined with a non-linear finite element analysis to study the effect of tendons pitting corrosion on the post-tensioned concrete bridge. The limit state function considered is flexural strength. The Monte-Carlo simulation (MCS) method is used to compute the statistical parameters of the resisting bending moment through a MATLAB code running ABAQUS. It was found that the reliability index for the first year of bridge service life is below the minimum value acceptable for structures. The study confirmed that this bridge was a high risk structure due to its design and location. The proposed framework can be used by engineers and researchers as a tool to support decision for segmental post-tensioned (PT) bridges maintenance since they need for a regular inspection due to their risk to corrosion.

Review of Electrochemical Testing to Assess Corrosion of Post-Tensioned Tendons with Segregated Grout

Post-tensioned (PT) construction incorporating bonded tendons with cementitious grouts has been used for highway bridges. The tendon duct and the encapsulating grout materials provide barrier corrosion protection for the embedded high-strength steel strand. Although generally used in good engineering practice, cases of PT tendon corrosion have been documented relating to inadequate detailing for joints and development of grout bleed water. Recently, in the past several years, unexpected severe localized strand corrosion has related to the segregation of thixotropic grouts. In the latter case, thixotropic grouts (that have been developed to mitigate grout bleeding) formed physical and chemical deficiencies that have been characterized to have high moisture content and elevated sulfate ion concentrations. The early presence of elevated sulfate ion concentrations in the deficient grout hinders stable steel passivation. The corrosion mechanism can be complicated due to the compounding effects of physical grout deficiency, moisture content, pore water pH, and the presence of sulfate ions. There remains interest to reliably assess corrosion of PT tendons with deficient grout. A review of electrochemical techniques and test methods used in earlier research by the authors to identify the role of sulfates on localized steel corrosion in alkaline solutions is presented. It was evident that different testing methods can reveal various aspects of the corrosion of strands in the deficient PT grout. The open-circuit potential and linear polarization method could differentiate corrosion activity between hardened and deficient grout environments but did not reveal the development of localized corrosion. Electrochemical impedance spectroscopy was useful to identify grout deficiencies by the differentiation of its bulk electrical properties. Potentiodynamic polarization and electrochemical noise technique were used to identify metastable and pitting in alkaline sulfate solutions representative of the deficient grout pore water.

Experimental testing and analytical modelling of single and double post-tensioned CLT shear walls

Post-tensioned (PT) timber technology - also called Pres-Lam technology - can provide increased strength/stiffness for mass timber seismic load resisting systems while also providing energy dissipation and re-centering capabilities. Initial experimental tests and practical implementation on PT timber structures in the past 15 years primarily utilized laminated veneer lumber (LVL), with some glulam and cross-laminated timber (CLT) prototypes and real-case applications, and their analytical prediction models were extended and adapted from precast concrete to account for unique characteristics of engineered timber. More recently, CLT has emerged into a more dominant global mass timber product. This paper presents a large-scale experimental study on 8.6 m tall PT CLT single and double wall systems. The PT double walls utilized screwed connections at the in-plane joint and U-shaped flexural plates at the foundation to provide coupling effect and energy dissipation. With screwed connections, the PT double wall partial composite action of approximately 70% was achieved and the system stiffness was almost two times that of two PT single walls without partial composite action but of equivalent length. Analytical prediction models, accounting for the peculiar controlled rocking mechanism and originally developed for PT LVL systems were adopted for PT CLT wall systems, were found to have increased compressive toe strain variability due to the increased material inhomogeneity of CLT with non-edge glued lamella. The timber compressive strains and unique ‘end effect’ bearing phenomenon was investigated for the first time with Particle Tracking Technology (PTT). Extensions to the existing PT double wall analytical prediction model were proposed and validated to capture the unique kinematic rocking mechanism where wall uplift occurs due to the strong and stiff screwed in-plane connection between individual walls.

Experimental evaluation of post-tensioned bridge bent under cyclic loads and comparison to hybrid bridge bents

Experimental results for a re-centering bridge bent whose concrete columns were post-tensioned with unbonded high-strength steel bars are presented. The initial post-tensioning forces to achieve column re-centering were obtained using rigid body analogy. Steel collars were provided at the top and bottom ends of the columns for confinement. The column-to-footing interface contained a polyurethane layer inside the shear key to reduce column damage. For the initial post-tensioning forces implemented in the experiment, concrete damage was observed at the bottom of the columns. The post-tensioned (PT) bars remained elastic up to the design drift ratio of 2.0% and yielded at a 5.0% drift ratio; the column longitudinal mild steel bars yielded at a drift ratio of 6.0%. The performance of the post-tensioned bridge bent without any external energy dissipators (PT-Only bent) was compared with that of two similar hybrid bridge bents reinforced with external energy dissipators: the first incorporating tension-only stretch length anchors, and the second incorporating a buckling restrained brace. The two hybrid bents displayed excellent performance compared to the PT-Only bent in terms of strength, stiffness, and hysteretic energy dissipation; however, the PT-Only bent had a superior re-centering efficiency compared to the two hybrid bents.