Precast Segmental Bridge Columns Research Articles

Seismic behavior of precast segmental bridge columns confined by grouted glass fiber reinforced plastic tubes

The application of precast segmental bridge columns (PSBCs) is still restricted in seismicity areas due to concerns such as lower lateral stiffness and column base bearing capacity. To enhance the applicability of PSBCs, this study proposed a novel approach of confining them with grouted GFRP tubes. Four novel and one reference specimens were tested under low cyclic loading to evaluate the effects of energy dissipation (ED) bars ratios, concrete interlayer strength, type of segment concrete, and concrete pouring methods within the outer GFRP tube (OGT) on the seismic behavior. Experimental results reveal that the failure modes of all specimens were triggered by the yielding of ED bars and the break of OGT at the top of ED bars. No crushed concrete at column bases or cracks at the segment joint were observed during the test due to the good confinement of GFRP tubes. All the specimens exhibited stable hysteretic behavior with small residual drift ratios and low strength degradation. Furthermore, finite element models (FEMs) were generated to predict the hysteretic behavior of novel specimens. The effects of some parameters such as OGT thickness, ED bars diameter, and concrete strength were further studied.

Self-Centering Precast Unit as Energy Dissipation Members in Precast Segmental Bridge Columns

This research aims to present a new generation of seismic-resisting systems designed for precast reinforced concrete (RC) bridge piers in modern sustainable cities to withstand moderate to high seismic activity. The proposed system consists of two self-centering (SC) systems operating in parallel to bring together all features of the required resiliency during a seismic action. The first/main system is a hollow core precast segmental bridge column, and the second is composed of an SC precast unit and energy dissipation (ED) steel reinforcements positioned in the main pier segment’s hollow core. To study the performance of the proposed system, a finite element model was first developed to capture the behavior of experimentally tested precast bridge columns. After validation, the created model was systematically studied to investigate the performance of the entire proposed system under cyclic loading. The effects of three parameters related to the ED system were investigated, including the reinforcement ratio, the unbonded length of ED bars, and the SC post-tensioned force ratio. Furthermore, the impact of FRP wrapping on the lower part of the core column of the ED system was also investigated. An analytical model predicting the characteristic points of the lateral response of the proposed system based on the superposition concept is also proposed. The FE results showed that the entire proposed system is a new design-based resilient system with the ability to dissipate energy without compromising the SC capacity of the main resisting system. Compared to the typical precast hollow core segmental column, a 6% reinforcement ratio of the ED unit can cause a 60% increase in lateral resistance and a 220% increase in the ED capacity. The analytical model can successfully be applied in the design of the proposed system to provide customized ED capabilities and controlled lateral resistance.

Responses of a System Comprising a Rigid Block with Resettable Sliding Key Under Base Excitation

The relatively uncontrolled dynamic behavior of a rigid block resting on a flat surface under ground motion has been well studied. In contrast, a block with a gently inclined V- or W-shaped sliding key would ensure dynamic self-centering or resetting performance under various seismic conditions. To better understand the nonlinear responses of rigid blocks having this type of interface where both rocking and sliding movements are possible, an event-based algorithm is put forward to cover various types of motions, including the transition stages between different types of motions. A comprehensive study is carried out to examine the dynamic responses of blocks of different sizes and aspect ratios. Moreover, the simplified pure rocking model and pure sliding model are also adopted to obtain rough estimates of dynamic response for comparison. The results show that the simplified models are reliable for some special cases only, e.g. squat blocks and slender blocks. The study also evaluated the influence of the coefficient of friction and slope inclination on the resetting capabilities of typical sliding-prone and rocking-prone systems. For those cases that are prone to toppling or excessive sliding under strong earthquakes, the provision of vertical post-tensioning can effectively ensure stability and resetting performance. Such findings provide insight into the performance of precast segmental bridge columns with resettable sliding joints.

Seismic performance of a GFRP–concrete–steel hollow section segmental column with SMA bars and replaceable ED devices

This paper investigates the seismic behavior of a novel precast segmental bridge column (PSBC). Glass fiber reinforced polymer (GFRP)-concrete-steel hollow section segments were used to construct the column. Hybrid energy dissipation (ED) system consisted of shape memory alloy (SMA) bars and replaceable external ED devices was proposed to increase the ED capacity of the PSBC. The SMA bars have a large deformation capacity, which makes them not easy to be damaged. They were therefore installed inside the column to absorb energy and more importantly to keep the residual displacement small. External ED devices were used to increase the overall ED ability of the PSBC. The external arrangement of the ED devices made it possible and easy for the post-earthquake replacement. A reference PSBC with steel-reinforced precast segments was also constructed and investigated. The test results demonstrated that, compared with the traditional PSBC, the proposed column exhibited appealing seismic performance, including better self-centering capacity, higher post-yield stiffness, and better ED ability. Furthermore, the proposed PSBC experienced minimal concrete damage during the test. One of the external ED devices fractured, however, they could be uninstalled and replaced easily. Numerical models were developed and used to conduct parametric studies. The results demonstrated the feasibility of using the hybrid ED system and the GFRP–concrete–steel​ hollow section segments to improve the performance of the PSBC under seismic loadings.

Design and seismic performance of precast segmental bridge columns repaired with UHPC jacket after earthquake-induced damage

Precast Segment Bridge Columns (PSBCs), which attract more attention owing to the merits of faster construction rate and higher construction quality compared with monolithic columns, are prone to serious damage under a severe earthquake. Seismic performance improvement and rehabilitation of earthquake-damaged PSBCs are significant to promote applications in seismic-prone areas. Ultra-high performance concrete (UHPC) jackets, which are promising in the field of rapid retrofit of civil structures, were used to retrofit damaged PSBCs in this study. To investigate the seismic design method and performance of repaired PSBCs using UHPC jackets, a 1/10-scale earthquake-induced damaged PSBC was retrofitted based on a proposed reinforcement design method, and tested under vertical loading and incremental lateral cyclic loading. The failure mode, hysteresis curve, residual displacement, and energy dissipation capacity of the repaired column were compared with those of the original column. In addition, based on a verified 3D finite element model by the test, a parameter analysis was conducted to explore the effect of the height and wall thickness of the UHPC jacket on the seismic behavior of the repaired PSBCs. The results indicated that the earthquake-damaged PSBC repaired with the UHPC jacket had an equivalent initial stiffness, 18.9% higher energy dissipating ability at 4.0% drift ratio and 16.2% larger strength compared with the undamaged column. The numerical simulation showed that the height and thickness of the UHPC jacket had an influence on the failure location and strength of the repaired PSBCs. Besides, the design method for the damaged precast column reinforced with the UHPC was confirmed by the test and finite element model, and it could be applied to the retrofit design of the damaged precast segment column.

Cyclic Bond-Slip Behavior of Partially Debonded Tendons for Sustainable Design of Non-Emulative Precast Segmental Bridge Columns

The precast segmental bridge columns incorporating resettable sliding joints have been proposed to extend the accelerated bridge construction techniques to regions of moderate to high seismicity while fulfilling the sustainability-based resilient seismic design concept. Following a rethink of the design strategy in the light of inspirations from hybrid sliding-rocking joints, the design of resettable sliding joints can accommodate a certain amount of horizontal sliding displacement and adopt partially debonded tendons in a vertical manner, probably resulting in complicated tensile-flexural loading scenarios in these tendons during earthquakes, which is rarely considered in practice. In this paper, the sustainable design of resettable sliding joints is introduced. A tailor-made setup was established and simplified cyclic bond-slip tests were conducted to validate the practicality of the proposed partially debonded tendon system. Twelve specimens were fabricated using different strands and grouting techniques, and a two-stage numerical model was proposed to interpret the experimental results of seven typical specimens. The results suggest that the deterioration of reloading stiffnesses can be captured by an additional effective length caused by bond failure, and the strands perform mostly elastically under relatively large transverse displacements. The loading stiffness of the anchorage is 26.3 kN/mm, and it has significant effects and the proposed two-stage model can satisfactorily capture the envelope of the response of the partially debonded tendons, providing practical design for the proposed partially debonded tendons used in sustainable non-emulative precast segmental bridge columns.

Dynamic response of precast segmental bridge columns under heavy truck impact

Dynamic response of precast segmental bridge columns under heavy truck impact

Experimental study and numerical simulation of precast segmental bridge column with a central RC tenon

In this study, a new connection method is proposed for improving the seismic performance of prefabricated reinforced concrete (PRC) segmental piers. In addition to the traditional grouted corrugated pipe (GCP), the new connection uses a reinforced concrete tenon (RCT) to strengthen the joint and improve the hysteretic performance of the pier under lateral loading. Experimental studies were conducted on three specimens with a scale ratio of 1:5 cast-in-place (CIP), PRC-GCP, and PRC-GCP-RCT piers. The responses of the tested specimens were compared using different performance metrics, and a comparison of the results showed that the GCP-RCT connection could provide a feasible solution because it significantly increased the lateral-load and energy-dissipation capacities of the pier. The GCP-RCT connection was also efficient in alleviating flexural damage and reducing residual displacement of the pier shaft. Moreover, three-dimensional (3D) finite-element (FE) models of the tested specimens, incorporating the contact effects between the connections of the two precast specimens, were developed in ABAQUS. Good agreement was obtained between the numerical and experimental results.

Review of experimental investigations on seismic performance of precast segmental bridge columns in seismic regions

Due to the fast construction and low interference, precast segmental bridge columns have gained increasing attention for use in non-seismic regions. However, their applications in seismic areas remain scarce due to their ambiguous dynamic performance. To estimate the seismic performance of PSBCs, existing quasi-static cyclic tests and shaking table tests are gathered and reviewed in this study. According to the structural details and material property at the joints, the PSBCs are categorized as 11 types based on the connection type, namely grouted splice sleeve couplers (GSSCs), grouted corrugated duct connections (GCDCs), wet joint connections (WJCs), mechanical bar splice connections, socket connections (SCs), unbonded post-tensioned tendon connections (UPTCs), partial precast columns (PPCs), hybrid connections (HCs), high-strength steel bars (HSBs), high-performance concrete (HPC), and external dissipators (EXDs). Based on the experimental results, the failure reason of each connection types are discussed and the effective structural details are suggested. And also, the PSBCs are divided into those with ductile and resilient connections according to the damage levels, residual drift ratios, displacement ductility coefficients, equivalent viscous damping ratios and effective stiffness parameters. With the achievements in this research, the application of PSBCs is expected to be promoted in medium-to-high seismic regions.

Axial behavior of precast segmental hollow bridge columns confined by grouted steel tubes

To avoid the problems of the conventional precast segmental bridge columns (PSBCs) such as the concrete crushing at column ends, joint openings between segments, and torsional deformation under seismic attacks, a novel type of precast segmental bridge column confined by a grouted steel tube (TPSBC) was proposed, and herein the axial compressive behavior of the TPSBCs was investigated by testing of 14 specimens. The main parameters of the tested specimens included the diameter-thickness ratios of the steel tubes, the number of the precast segments, reinforcement arrangements in the precast hollow segments, initial prestress levels, sandwich concrete strengths, and loading forms. The effects of the parameters on the failure modes, loading bearing capacity, ductility, and steel strain development of the specimens were evaluated. The test results indicate that the proposed TPSBCs with proper configurations exhibited desirable compressive behavior with significantly improved load bearing capacity and deformability compared with the PSBCs. Based on the analysis of the confinement effects, analytical models were developed for predicting the axial bearing capacity of the TPSBCs under the different loading forms.

Comparison study of time-varying seismic fragility of precast segmental and cast-in-place bridge columns in high-speed railway bridges

In recent years, precast segmental bridge columns (PSBCs) have been widely used in high-speed railway bridges, but the lack of long-term seismic performance limits PSBCs application in harsh environments and high-intensity areas. However, the selection of high-speed rail lines in high-intensity offshore areas is inevitable. Therefore, considering the impact of environmental erosion and earthquake, it is necessary to study the seismic performance of PSBC. In order to study the application of PSBCs in offshore high-intensity areas, this paper comprehensively compares the time-varying seismic fragility of PSBCs and cast-in-place bridge columns (CPBCs) in high-speed railway bridges. Based on offshore high-speed railway columns, the finite element models of representative PSBCs and CPBCs are established and verified by experiments. Then, the verified finite models are utilized to implement the time-varying fragility analysis by considering chloride ion erosion under four damage states. The main conclusions are as follows: the exceeding probabilities of PSBCs and CPBCs are close in intact bridges under different damage states and seismic intensities. With the prolongation of bridge service time, the steel bars corrosion rate of PSBCs is faster than that of CPBCs due to the discontinuity of PSBCs segments, the exceeding probabilities of PSBCs increase more rapidly than those of CPBCs. When the columns reach the design working life, the exceeding probability and PGA (Peak Ground Acceleration) median of PSBCs are higher than those of CPBCs under four damage states. Taking the moderate damage state as an example, the maximum exceeding probability of PSBCs and CPBCs were 97.2% and 89.1%, respectively, and the PGA median of PSBCs were 24% lower than that of CPBCs at 100 years. This work provides a theoretical foundation for the better application of PSBCs in offshore high-intensity areas.

Seismic Performance of Precast Segmental Bridge Columns Reinforced with Both Stainless-Steel Bars and GFRP Bars

Abstract An innovative precast segmental bridge column (PSBC) was proposed to achieve a better durability performance in an aggressive coastal environment, which was reinforced with both longitudin...

Experimental study of durable low-friction concrete contacts for precast segmental columns with resettable sliding joints

Planar sliding joints have been introduced to precast segmental bridge columns to alleviate the detrimental effects of earthquakes. However, residual sliding movements may result from strong shaking. Resettable sliding joints comprising V-shaped or W-shaped interfaces of gentle inclinations have been proposed to achieve better resilience against seismic actions in regions of moderate to high seismicity. However, possible deterioration of the frictional performance at the concrete contact surfaces may affect the resetting performance of these joints. In this regard, the tribological features, performance and durability at the interface of resettable sliding joints in precast segmental bridge columns were investigated experimentally utilizing 3D printed moulds and computed tomography scanning technology. Various surface treatment and lubrication methods were evaluated monthly up to 360 days after casting based on a modified cyclic direct shear apparatus at high loading pressure. Results show that high-performance PTFE grease lubricant is useful in achieving and maintaining favourable coefficients of friction as low as 0.05.

Precast segmental bridge columns with resettable sliding joints —— An inspiration from ancient Chinese pagodas

The construction of bridge substructures by in-situ assembly of precast concrete segments provides significant benefits in quality control and economy, but their seismic stability is always a concern. Incidentally, prefabricated components have long been used in building tall pagodas for thousands of years in China. Among the pagodas that have survived numerous centuries, the timber pagodas are believed to be assembled structures of great research value in respect of seismic isolation design. There is indeed a certain degree of similarity between the timber pagodas and the proposed precast segmental bridge columns with resettable sliding joints. The smart seismic isolation mechanism in multi-storey timber pagodas with mortise-tenon rocking columns and distributed bracket sets has the following key features: (a) high lateral flexibility, (b) smart energy dissipation system, (c) guided self-centring behaviour, and (d) measures to enhance vertical stability. Actually, the resettable sliding joints in the present precast segmental bridge columns are so designed and distributed to obtain a similar seismic isolation mechanism. Time-history simulation results of seven conceptual models show that the columns with resettable sliding joints outperform the other counterparts especially in respect of (a) the overall seismic isolation between the top mass simulating the deck and the shaking ground, (b) the control of residual sliding displacements at segment interfaces, and (c) satisfactory energy dissipation performance.

Seismic behavior of precast segmental bridge columns reinforced with hybrid FRP-steel bars

Precast segmental bridge columns (PSBCs) are a key component in accelerated bridge construction. In order to advance the technology and improve their seismic resistance, this paper presents research on an innovative PSBC system that incorporates both fiber-reinforced polymer (FRP) bars and steel bars as longitudinal reinforcement. The system, which is referred to as an FRP-steel reinforced PSBC (FSR-PSBC), utilizes hybrid FRP-steel bars to increase the post-yield stiffness and to decrease the post-earthquake residual drift. The first part of the paper presents the results of cyclic loading tests of large-scale PSBC systems. Several important trends were observed. (1) Compared to traditional steel-reinforced PSBCs, the post-yield stiffness ratio of the FSR-PSBC system increased by up to 93%, while the residual drift ratio reduced by 68% at a large drift of 4%. (2) The FSR-PSBC specimens exhibited energy dissipation capacities comparable to their steel-reinforced counterparts. (3) Carbon FRP bars of the hybrid reinforcement significantly contributed to the increase of the post-yield stiffness and self-centering ability of the FSR-PSBC system. The second part of the paper presents a design-oriented analysis of the test results. Three possible compression-bending failure modes of the FSR-PSBC system are proposed and a desired ductile failure mode was established. Then, three damage limit states within the ductile failure process were defined in terms of the responses of materials, displacement and residual drift. The analysis presented paves the way for the development of a performance-based seismic design method for an FSR-PSBC system.

Resetting response of precast segments with gently keyed interface under seismic action

SummaryIn an attempt to promote the use of precast segmental bridge columns in regions of moderate to high seismicity, sliding planar joints have been adopted to relieve the adverse effects of seismic action. However, despite the ability to survive an earthquake, the sliding segments often result in noticeable residual relative movements afterwards, which require costly repairs. To better understand the kinetic and self‐centering performance of sliding segments with W‐shaped gently keyed interface, the concept of sliding hysteresis center curve is put forward. A bidirectional asymmetrical pure sliding model is explored for better control of the self‐centering ability, where the downslope slip caused by the energy at the post‐peak stage of an earthquake may benefit the self‐centering performance of asymmetrical sliding systems. A series of parametric studies using real earthquake records are then conducted to evaluate the effects of inclination θ and coefficient of friction μ at the interface on the dynamic response. It is found that the seismic excitations, especially the post‐peak cycles, have profound influence on the residual displacement of an asymmetrical sliding system. With proper design, a W‐shaped gently keyed sliding system can provide superior self‐centering performance without affecting its seismic isolation ability during the peak stages of earthquakes.

Seismic performance of self-centering precast segmental bridge columns under different lateral loading directions

Self-centering precast segmental bridge columns (SC-PSBCs) have been intensively investigated in the past decade as one of prefabricated bridge components to expedite construction and improve seismic resilience. However, the application of SC-PSBCs is limited to the low seismicity areas due to insufficient knowledge about their seismic performance. In particular, the behavior of SC-PSBCs is not clear under multi-directional seismic excitations. In order to investigate the effect of lateral loading directions on the seismic performance of SC-PSBCs, five 1/10-scale identical SC-PSBC specimens with rectangular hollow sections were designed and tested under lateral cyclic loading and a constant vertical load. Each specimen was loaded at a specific angle with respect to the weak axis of the column section. The loading angles included 0, 30, 45, 60, and 90 degrees. The seismic performance of the specimens was evaluated and discussed using the test results. It was found that the SC-PSBC specimens were of good ductility, and the favorable self-centering capacity was obtained under orthogonal loading directions. Only considering the orthogonal loading direction in the design of SC-PSBCs is non-conservative since it may underestimate the local damage and residual displacement. The extent of prestress loss in each strand was very sensitive to the relative distance to the neutral axis depending on the loading directions. The equivalent viscous damping ratios of SC-PSBCs were in the range from 0.151 to 0.198 at a drift ratio of 4.0%.

Seismic performance of precast segmental bridge columns repaired with CFRP wraps

Precast segmental bridge columns (PSBCs) have many advantages compared with monolithic bridge columns. However, PSBCs could be severely damaged during an earthquake due to their limited seismic capacity. Rapid repair of the PSBCs and the seismic behavior of the repaired PSBCs are critical to the post-earthquake recovery of bridges with such columns. In this study, an original PSBC specimen is designed, constructed, and tested under cyclic loading. After the cyclic test on the original specimen is carried out, carbon fiber reinforced polymer (CFRP) sheets and sticky steel glue are used to repair the damaged specimen. The repaired PSBC specimen is then tested under the same loading protocol as the original specimen to compare their cyclic performance. Test results show that the concrete damage of the repaired specimen is reduced compared to the original specimen, and the repaired column has a relatively larger energy dissipation and residual displacement than those of the original column. To leverage the test results, detailed three-dimensional finite element models are developed and calibrated with the results from the experiments. Closely replicating the test results, the validated finite element models are used to replace the lab experiments for the parametric modeling of the seismic performance of bridges with PSBCs while capturing effects of CFRP. Specifically, the influence of CFRP design variables, including the CFRP cross-sectional area ratio and the CFRP height ratio, on the seismic performance of the repaired PSBCs is evaluated by using the validated finite element model. It is found that the CFRP cross-sectional area ratio has little effect on the seismic capacity of the repaired PSBCs, and the repaired PSBC with a CFRP height ratio of 2.0 is the most suitable for the repaired PSBCs investigated in this study.

Cyclic loading tests and analyses of posttensioned concrete bridge columns combining cast-in-place and precast segments

This paper investigates the seismic performance of posttensioned concrete bridge columns combining cast-in-place and precast segments to achieve optimal response to cyclic loadings and construction. For this purpose, a monolithic bridge column (MBC), a hybrid bridge column with a combination of precast segments and a cast-in-place column base (HBC), and a precast segmental bridge column (PSBC) were designed and built. The three columns were subjected to cyclic loading to assess the seismic capacity. Experimental data showed the HBC to have better performance regarding hysteretic characteristics, energy dissipation, and stiffness degradation compared to the PSBC. The HBC and PSBC both exhibited significantly higher self-resetting capacity than the MBC. The corresponding numerical simulations were conducted based on OpenSees platform, and the results were compared with the test data. Using the validated numerical model, further parametric analyses were carried out to assess the energy dissipation capacity of the HBCs. This was found to increase with the height-to-diameter ratio of the cast-in-place column base until a certain threshold. A reasonable height-to-diameter ratio of the cast-in-place region with different axial compression and longitudinal reinforcing ratios could be defined for improving the energy dissipation capacity in seismic design of the proposed HBCs.

Cyclic Load Tests on Precast Segmental Bridge Columns with Both Steel and Basalt FRP Reinforcement

AbstractThis paper presents an experimental investigation of a novel precast segmental bridge column (PSBC) that is longitudinally reinforced with both fiber-reinforced polymer (FRP) bars and conve...