Precast Piers Research Articles

Numerical Simulation Analysis of the Seismic Performance of Precast Bridge Piers

Precast technology is increasingly favoured by bridge engineers, and the seismic performance of precast bridge piers urgently needs to be addressed. Precast piers have a complex load-bearing mechanism, and their design method has not been clearly determined. Fibre plastic hinge theory can satisfactorily analyse the seismic performance of precast piers. In this study, the seismic performance of precast piers is analysed through numerical simulation of pier columns based on the pseudostatic testing of a set of existing precast piers and combined with fibre plastic hinge theory. The results show the following: With reasonable constructional measures, precast piers connected by grouted sleeves indeed have seismic performance similar to that of cast-in-place components. Finite-element programs can be employed to simulate the mechanical properties of steel rebars before yielding well but not those after yielding or under fatigue. When fibre plastic hinges are used for finite-element analysis, if the fibre cross-section is reasonably divided, the length of the plastic hinge has little influence on the results; otherwise, too densely distributed plastic hinges may lead to nonconvergence of the results in a later working condition. The plastic hinge method recommended in this paper, especially the sectional fibre-cross-section division method, can obtain the plastic hinge performance state, it can help save the test cost and make up for the shortage of test data.

Pseudostatic Behavior of Precast Piers with Composite Pier–Pile Cap Connections: Experimental Investigation

Pseudostatic Behavior of Precast Piers with Composite Pier–Pile Cap Connections: Experimental Investigation

Load transfer mechanism of precast concrete piers with demountable connections

To investigate the replacement or rehabilitation of precast concrete piers, a novel demountable steel-concrete composite connection with notched perfobond connectors was proposed for the pier-pile cap joint. In the proposed connection, a bolted mechanical connection is used to connect the longitudinal reinforcing bars and steel plate, which is bolted to the pile cap through pre-stressed anchor bolts. Pseudo-static capacity tests of two half-scale specimens were conducted with different axial compression ratios, and the experimental results were verified by nonlinear finite element analysis. The lateral force-displacement curves, failure modes of connection joint, stress of steel plates and connector-concrete slip were compared and discussed. Furthermore, the internal load transfer mechanism and characteristics were revealed. The results indicate that the precast pier with the proposed connection realizes the rapid assembly and demountability. Specimens present flexural failure, and damage appears at the bottom of the pier columns but above the steel jacket. The connection steel plates and bolted connection remain intact as expected. The stiffness, capacity and failure process in numerical analysis agree well with the experimental results. The notched perfobond connectors set on the base plates effectively transfer the force from the concrete column to the base plate, and enhance the base plate-concrete connection and bending resistance of the base plate.

Development of Assembled Precast Pier with Crimped Construction by Prestressing─Unit-Type Construction with Factory-Produced Precast Concrete Members─

Development of Assembled Precast Pier with Crimped Construction by Prestressing─Unit-Type Construction with Factory-Produced Precast Concrete Members─

Seismic performance analysis of self-centering segment piers with mortise-tenon shear connectors based on cyclic pseudo-static test

In the past decades, more and more precast piers have been used in actual engineering, which brings convenience in construction and standardization of production. However, precast piers still have some shortcomings, such as shear slip between segments and poor energy dissipation. Thus, a self-centering mortise-tenon segmental bridge pier was proposed in this paper. To research the seismic performance of the self-centering mortise-tenon segment piers, three scaled model piers with their scale ratio as 1:3 were designed and prefabricated, namely as a cast-in-place model pier (CP) and 2 self-centering mortise-tenon segment model piers (designated as MTSP1 and MTSP2) with the initial pretension of 1302 MPa and 1488 MPa, respectively. The cyclic pseudo-static tests of the three piers were carried out. The comparison analysis was made respecting to the test results including the damage form, hysteretic characteristics, skeleton curve, energy dissipation capacity, residual displacement and equivalent stiffness of the three specimens. It was shown that MTSP specimens had higher horizontal bearing capacity. While the yield load, ultimate load, displacement ductility coefficient and initial stiffness of MTSP1 and MTSP2 were higher than those of CP. The MTSP had better performance considering the above aspects. The mean value of the residual displacement of MTSP2 was lower than that of CP 21.14 % and 29. 72 % respectively, as the drift ratio reaching 5 %. The MTSP specimens had better self-centering capacity due to the increased pretension stress which reducing the residual displacement greatly. The energy dissipation reinforcements improved the energy dissipation capacity of the segmental assembled piers. Based on the ABAQUS model, the numerical simulation was carried out and compared with the experimental data. MTSP had great energy dissipation capacity and self-centering capacity. It was suggested that MTSP should be used to make up for the deficiency of segmental assembled pier and improve the seismic performance of segmental assembled pier.

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 investigation of seismic behavior of UHPC connection between precast columns and footings in bridges

The lack of seismic capacity of piers leads to bridge collapse in recent earthquakes, such as the 1994 Northridge (USA), 1995 Kobe (Japan) and 2008 Wenchuan (China) earthquakes. For precast bridge piers, the performance of pier connection determines the seismic capacity of the whole bridge. Therefore, a new connection between precast bridge column and footing using ultra-high performance concrete (UHPC) is developed in this paper. The precast column and footing are connected by longitudinal rebars of the column and the footing anchored into the UHPC-filled cage. The connection allows force to be transferred from the column rebars to UHPC, then to the footing rebars by bond effects. To investigate the seismic behavior of precast bridge piers with this new UHPC connection, cyclic tests with two large-scale (1:2.5) models are carried out. One is the precast reinforced concrete (RC) specimen using the proposed new connection, and the other is the cast-in-place (CIP) RC reference. The results show that the failure modes of the specimens are similar, both denoted by crushing of the core concrete above the connection segment. No obvious damage is observed in the connection region, which demonstrates that the precast bridge pier with the proposed connection is emulative of the CIP pier. Furthermore, a finite element model is developed to simulate the cyclic response of the precast column with proposed connection. The deviation between the calculated and measured force–displacement relationships is about 5%, which indicates that the numerical model used herein can be effective to capture the performance of the precast pier with new UHPC connection.

Seismically Resilient Hybrid Precast Concrete Piers with Ultrahigh-Performance Concrete

Abstract This paper investigated a novel hybrid precast pier system that utilized ultrahigh-performance concrete (UHPC). The pier combines features of emulative and nonemulative (of cast-in-place c...

Seismic performance of grouted sleeve connected precast pier based on steel hysteretic model

The static and quasi-static behaviors of cast-in-place pier and grouted sleeve connected precast pier are simulated by ABAQUS, which are based on the steel hysteretic constitutive model. The accuracy of the finite element simulation is verified by comparing with the existing experimental results. Then the simulation results of the two types of piers are compared and analyzed. The results show that: the seismic performance of precast pier connected with grouting sleeve is similar to that of cast-in-place pier, they both have good plastic deformation capacity. When the displacement is large, grouting sleeve connected pier has higher hysteretic energy dissipation than that of cast-in-place pier, it’s suitable in high earthquake region; The steel hysteretic model can better simulate the seismic performance of reinforced concrete structure under cycle load.

THE SEISMIC PERFORMANCE OF PRECAST BRIDGE PIERS WITH GROUTED SLEEVES

The grouted sleeves embedded in precast column bodies were taken as the research object. The mechanical behavior of the column-to-footing joint and the influence on the overall seismic performance of this kind of bridge piers were theoretically analyzed. A quasi-static test of precast bridge piers with grouted sleeves was carried out. The difference between the seismic performance of the cast-in-place piers and the precast bridge piers with grouted sleeves was compared by a numerical simulation. The influence of different sleeve diameters and lengths on the seismic performance of the bridge piers was also investigated. The results show that the precast piers with grouted sleeves were easy to form a rigid region in the connecting section due to the large rigidity of the sleeves, and that the redistribution phenomenon of the curvature occurred in the columns, resulting in an increase in the curvature and rebar strain concentration adjacent to the end of the sleeves. In addition, the precast bridge piers with embedded grouted sleeves in the plastic hinge area were found to have a reduced displacement capacity as compared to cast-in-place piers with the same reinforcement. This phenomenon was more serious when a larger sleeve diameter was adopted. The larger the diameter and the longer the length of the sleeves, the more obvious the strain concentration at the joint, which resulted in the transformation of the final failure form of the pier from the traditional concrete failure in the plastic hinge area to steel fracture in the joint at the bottom of the pier.

Seismic behaviors of precast assembled bridge columns connected with prestressed threaded steel bar: Experimental test and hysteretic model

Three 1/10-scale bridge pier specimens were tested under quasi-static test. The specimens included two precast specimens (PC1 and PC2) and one cast-in-place reference specimen. The two precast bridge pier specimens were connected with prestressing threaded steel bar and steel flange at the connection between precast pier column and the foundation, and non-socket assembly scheme and socket assembly scheme are adopted, respectively. They were tested to verify the seismic performance of prefabricated piers connected by prestressed threaded steel bars and steel flanges and study which assembly scheme is better for non-socketed and socketed piers. The results show that the prefabricated pier with the combination of the prestressed threaded steel bars and steel flange has higher cracking load and smaller residual displacement, which indicates that it has good service performance and good self-resetting ability. Compared with the non-socket assembly scheme, the socket assembly scheme is superior due to its higher ductility, higher overall initial stiffness, and higher energy dissipation capacity. Therefore, the prefabricated assembled pier with the socket connection scheme of the combination of the prestressed threaded steel bars and steel flange has good service performance and seismic performance. After that, a hysteretic model for the precast assembled columns was proposed, which has a good agreement with the test results.

Cyclic load behavior of precast self-centering hammer head bridge piers

ABSTRACT Five-hammer head bridge piers were fabricated and tested under cyclic lateral loading to evaluate the hysteretic response and the self-centering capability. The failure modes, hysteretic load-displacement loops, dissipated energy, and residual displacement were observed and analyzed. In addition, the seismic performance of proposed construction method with and without energy dissipation rebar, different level of posttensioning were studied. The test results were used to verify the Finite Element Model (FEM) developed in this study. Tested specimens were modeled using the ABAQUS platform under quasi-static loading. The analytical model considered interaction between precast elements, unbonded strands, and surrounding concrete and bond slip between column main reinforcement and concrete. Developed FEM for monolithic bridge pier showed comparable results with the experimental tests. FEM was able to predict the hysteretic behavior of modeled bridge piers with high degree of accuracy. In addition, FEM confirmed the experimental observations and showed that precast self-centering hammer head bridge piers system is capable of withstanding any large lateral displacements before achieving the peak lateral strength. Sensitivity analyses was conducted to investigate the effect of mesh size and bond-slip interaction. Finally a parametric study was conducted to study the effect of construction method, energy dissipation rebar ratio and socket depth on the hysteretic response of the modeled bridge piers. This study reveals that FE analysis using the proposed model is validated to be used in determining the appropriate range of applied posttensioning force; energy dissipation rebar ratio and recess depth.

Quantitative Definition of Seismic Performance Levels for Precast Bridge Piers with Continuous Reinforcement

For construction sites within cities, which require fast construction because of restrictions in road occupation time, or for other occasions where construction period is an important factor because of similar reasons, application of a modular construction method using precast members is efficient in terms of shortening the construction period. The substructures of bridges are normally constructed using cast‐in‐place, which has been a major cause of delays in construction. Application of a modular construction method could decrease the occupation time in the sites. A prime example is the Accelerated Bridge Construction (ABC) by the Texas Department of Transportation (TDOT) and Federal Highway Administration (FHWA). Precast members are the key components of ABC. The main purpose of this paper is to provide clear seismic performance standards for precast bridge piers. Current seismic design codes require force‐based design checks and provide qualitative evaluation of the overall structure. They do not provide specific qualitative criteria for individual structures with particular types. Previous research has been focused on reinforced‐concrete bridge piers, while lacking on research towards prefabricated bridge piers with continuous reinforcements. In order to quantitatively evaluate the seismic performance level of prefabricated bridge piers, the seismic performance was quantitatively suggested in accordance with the classification of four which are operational, immediate occupancy, life safety, and collapse prevention. These criteria are cracking of cover concrete, crushing of cover concrete, yielding of axial steels, and fracture of axial steels. Based on the given seismic performance evaluation criteria, evaluation and verification were conducted on four prefabricated bridge piers with continuous reinforcement that have undergone quasistatic cyclic experiments. The moment‐curvature analysis model was constructed for the parametric study and verified through experimental results. Based on the developed M‐Phi model, prefabricated bridge piers with continuous reinforcement, which were designed force‐based using response correction factor, were evaluated. In addition, parametric study was also conducted focusing on concrete strength, magnitude of prestress, and transverse reinforcement. Depending on the level of individual performance produced by ranges of these variables within possible runs on actual piers, the impact of 3 variables was analyzed. Furthermore, in response to changes in each variable, the impact on the relevant seismic performance level was verified through response spectrum analysis.

Seismic Evaluation of Precast Piers with Different Rebar Strength Based on Characterized Resilience Parameters

Abstract The use of precast pier segments is an integral part of many accelerated bridge construction efforts. To effectively compensate for the adverse effect caused by the concrete discontinuity between precast segments, replacing conventional rebar with high-strength steel (HSS) rebar can be an alternative to this issue. However, the primary interest in design practice is how to evaluate the seismic performance of precast piers with different rebar strength. To this end, a seismic evaluation method based on the four characterized resilience parameters was developed, which related to energy consumption, stiffness degradation, residual displacement, and drift capacity. According to the physical significance of the parameters, their desired expectations were expounded. In order to investigate the impact of rebar strength, an experimental program of the two precast piers was conducted, and the hysteretic curves were obtained. By comparatively analyzing the envelope curves of the two precast piers, the characterized resilience parameters were calculated and evaluated. It conclusively showed that the precast pier with HSS rebar was better than the one with conventional rebar at large. The proposed method based on the characterized resilience parameters is an effective tool to evaluate the seismic performance of bridge piers.

Analytical Pushover Method and Hysteretic Modeling of Precast Segmental Bridge Piers with High-Strength Bars Based on Cyclic Loading Test

AbstractCompared to cast-in-place bridge piers, precast piers can accelerate bridge construction, but their use in seismic systems is challenging. High-strength bars (≥500 MPa) incorporated with p...

Three-Dimensional Information Delivery for Design and Construction of Prefabricated Bridge Piers

This paper reports on the development and fabrication of precast bridge piers with unique creative shapes and more accurate geometry control methods using building information modelling, a new form of information processing and collaboration in which data are embedded within 3D models. Panelized formworks were created by digital fabrication from the 3D design models and attached to common steel formworks. During fabrication of precast segments, key parameters for geometry control were captured by laser scanning. The design models from the algorithm modelling were compared to fabrication models to provide error adjustment during assembly. Before assembly of the segments at a construction site, instructions for geometry control were provided to ensure the final target geometry of the bridge piers. Information delivery from design to maintenance can be achieved by 3D information models and a new format for drawings that includes QR codes and 3D models.

Behaviour of a column–bent cap connection for a precast DSCT column

Considerable progress has been made in bridge construction technology with regard to reducing construction times and incorporating green technologies. In the past, the time required to fabricate a tubular pier represented approximately 50% of the total construction time needed to build an entire bridge, and many researchers have therefore shown interest in studying the construction methodology of precast piers. In this work, a column–bent cap joint for a prefabricated double-skinned composite tubular pier was developed and its application was verified through testing. Test methods, including a cyclic eccentric loading test and a static compressive loading test, were developed to evaluate the performance characteristics of the column–bent cap connection. The major parameters were analysed and a standard model for the column–bent cap connection was developed through cyclic and static testing of structural elements.

Comparison study on hysteretic energy dissipation and displacement components between cast‐in‐place and precast piers with high‐strength bars

Precast piers incorporated with high‐strength bars (≥500 MPa) have great potential to accelerate bridge construction and enhance seismic performance. Four large‐scale pier column specimens using high‐strength bars by cast‐in‐place (CIP) and precast construction were experimentally studied. The distinctions of damage pattern between CIP and precast piers were characterized by plastic hinge and toed hinge, which expounded the smaller damage in precast piers. In contrast with CIP piers, the energy dissipation of precast pier was reduced by approximately 50–60% after pier yielding. An appropriate reinforcement ratio was essential for CIP piers to maintain enough displacement ductility and prevent premature fracture of energy dissipation bars. In terms of displacement components, the plastic term of precast pier was much smaller than that of CIP pier, and the gap opening‐induced displacement predominates after pier yielding. The toed hinge was elaborated to disclose the displacement mechanism in precast piers. The experimental findings in this paper can provide additional input for seismic design of precast piers with high‐strength bars.

Proposal of a New Partially Precast Pier Cap System and Experimental Verification of its Structural Performance

The purpose of this study is to suggest a new partially precast pier cap system and to experimentally verify its structural performance. The optimum shape and reinforcement detail of the partially precast pier cap were first derived and an improved manufacturing process in the precast plant and on-site was suggested. The new pier cap system offers benefits in terms of economy and quality management, and it can be constructed more rapidly than the conventional pier cap and fully precast pier cap. The specimens were manufactured at a one-half size of the original scale for structural tests. The tests highlighted that the loads at cracking, yielding and failure of the partially precast pier cap were almost identical to those of the conventional pier cap. Consequently, this study verified that the partially precast pier cap system can be applied for actual design and construction of the pier caps.

Seismic CFST Column-to-Precast Cap Beam Connections for Accelerated Bridge Construction

Concrete-filled steel tubes (CFSTs) frequently are a more efficient and economical structural solution then conventional reinforced concrete and structural steel. For the same size member, CFSTs offer increased strength and stiffness as well as accelerated construction. CFSTs may be used for bridge columns that will yield under earthquake loading, but this requires robust connections capable of sustaining large cyclic loads. To facilitate accelerated bridge construction, precast cap beams and girders are commonly used. Although CFST column-to-foundation connections have been studied, CFST column-to-precast cap beam connections have not. This is the focus of this research study. In contrast to cast-in-place (CIP) components, precast pier cap connections require additional design considerations including construction methodology and limits on geometry. To investigate this connection an integrated analytical and experimental research program was performed. Initially, continuum finite-element methods were used to conduct a parametric study; the results from that study determined the values of the study parameters and selection of the experimental specimens. Three different connection types were studied: (1) an embedded ring CFST, (2) a welded dowel, and (3) an interior reinforced concrete connection. Large-scale, pseudostatic tests were conducted. Results from the experimental investigation showed that the three connection types provide excellent deformability under reversed-cyclic loading and minimized damage in the cap beam.