Accelerated Bridge Construction Research Articles

Modelling non-linear dynamic behaviour of rocking bridge piers with shape memory alloys

In recent years, accelerated bridge construction has led to the substantial application of precast post-tensioned segmental (PPS) bridge piers. However, PPS piers are not widely used in high-seismicity regions due to their low energy-dissipation capacity (EDC). To address this deficiency, a series of shape memory alloy (SMA)–concrete composite PPS piers were examined in this work. Non-linear static and dynamic analyses were performed on experimentally validated finite-element models of the SMA–concrete composite piers and the results were compared with those of piers without SMA bars. It was found that the length, area and post-tensioning ratio of the SMA bars affected the EDC of the piers, and an optimal design of the bars is required to reach the highest EDC possible. The effects of SMA bars on the frequency response functions of piers were investigated for the first time in this study and it was found that, unlike the piers without SMA bars, sub-harmonics and super-harmonics were not seen in the responses of the SMA–concrete composite piers, mainly the drift responses. Furthermore, the SMA–concrete composite piers experienced a significant reduction in drift responses compared with piers without SMA bars.

Mechanical behavior of splice joints for bridge columns connected by grouted sleeves

Grouted sleeves are widely adopted in accelerated bridge construction (ABC), and connecting column segments by splice joints. As a part of column structure in prefabricated bridges, mechanical behavior of splice joint under seismic load is paid less attention. 4 scaled precast columns connected by grouted sleeves (PCCGS) with low aspect ratio under cyclic lateral loading were performed, giving the damage mode, force and deformation ability of splice joints. The splice joint of specimen was then sliced to investigate the inner failure at the joint surface and obtain bond-slip of contact between steel and grout. Finite element model (FEM) with refined mesh was established to reveal the damage mechanism of splice joint and lateral force and displacement of column top. A computational model was proposed to predict the force-displacement of splice joint, innovatively considering bond and slip between rebar and sleeve. The FE model and computing model are helpful to conduct seismic designing of PCCGS.

Experimental and numerical analysis on flexural behavior of improved U-bar joint details for accelerated bridge construction

U-bar loop connection is achieving widespread applications in the precast deck panel systems for accelerated bridge construction (ABC), while the welding operations on U-bars poses massive inconvenience and serious cost to the on-site assembly of precast deck panels. To eliminate the heavy welding operations and provide guidelines for design and detailing of U-bar loop connection, a total of nine specimens associated with three U-bar joint details are designed and examined through four-point bending tests. The experimental results suggest that welded splices can be omitted without affecting the moment capacity of wet joints. A notched double-loop connection is further developed to resolve fit-up issues resulting from the interference between studs and U-bars. The joint details involve setting notches at both ends of precast panels and placing additional looped bars in the specifically designed notches. The looped bars inserted in notches overlap with U-bars embedded in precast panels, therefore achieving the continuity of longitudinal reinforcement. The U-bar joints exhibit flexural failure characteristics and satisfactory bearing capacity in the experiment. Furthermore, the influence of lap length, concrete and steel grade, and lacer bars on the flexural behavior of U-bar joints is investigated based on 182 FE models, and the minimum lap length for spliced U-bars in notched double-loop connection is thereby determined. Besides, the proposed equations provide an estimate for the minimum lap length with reasonable accuracy.

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.

Investigating the Impact of Alternative Technical Concepts for Project Delivery of Accelerated Bridge Construction

Investigating the Impact of Alternative Technical Concepts for Project Delivery of Accelerated Bridge Construction

Shake table testing of out-of-plane response of repaired bridge subassembly with simplified ABC-inspired cast-in-place joints

Accelerated bridge construction (ABC) has been utilized in precast bridge structures because of its advantage to expedite on-site construction. In ABC, one of the main concerns is the joint connection as it needs to be well designed to maintain structural integrity. A recent study at the University of Nevada, Reno (UNR) was conducted to utilize ABC pocket connection concept in cast-in-place (CIP) cap beam-column bridge joint. The cap beam was constructed by having the cap beam longitudinal reinforcement bundled outside the pocket joint allowing the placement of the column reinforcement cage uninhibited. The specimen was tested in an inverted position at one of UNR’s shake tables and found to perform well under out-of-plane ground motion excitations, and the ductility of the column was confirmed through typical plastic hinge behavior. In this study, the specimen from the recent UNR test was further utilized by removing the damaged column in the cap beam through cutting and coring. A new column was constructed in the cap beam using the same reinforcement detailing from the original specimen. The repaired specimen was tested using the same loading protocol adopted from the 1994 Northridge earthquake as the original model. The objective of this study is to demonstrate that ABC-inspired CIP joints can provide a viable repair method after major earthquakes, where damaged columns can be replaced without affecting cap beam reinforcement. The repaired specimen performed well as the plastic hinge zone was developed in the column outside the joint, close to the interface of the cap beam, as desired and required by design. The cap beam remained essentially elastic, i.e. capacity-protected as required, throughout the test which is similar to the performance of the original model. High residual drift ratios were recorded at higher earthquake motions and were attributed to the slippage of the column in the joint. The paper also concludes with recommendations for the repair of CIP cap beam-column joints emulating ABC pocket connections.

Shear Behavior of Low-Aspect-Ratio Precast Bridge Columns with Grouted Sleeve Connection Considering the Effect of Axial Load Ratios

To promote accelerated bridge construction (ABC), precast bridge columns are now being more widely used in engineering applications. Researchers have often studied the seismic performance of precast bridge columns, but the study of shear performance is quite limited. The main purpose of this study is to investigate shear behavior of low-aspect-ratio precast columns with grouted sleeve connections considering the effect of axial load ratios. Cyclic quasistatic tests of four 1/4-scaled reinforced concrete precast column specimens were conducted to investigate their seismic performance. The experimental results showed that large axial load reduced ductility factor of columns, but increased lateral force capacity. A predicting method for lateral force capacity of precast bridge columns based on a strut-and-tie model in the sleeve region was developed. The method can realistically predict the lateral force capacity and take into the influence of axial load on lateral force capacity of precast columns with grouted sleeve connection.

Experimental and Numerical Investigation of Prefabricated Concrete Barrier Systems Using Ultra-High-Performance Concrete

The functionality and crashworthiness of concrete barriers in bridge systems can be affected by the deterioration of the connection between bridge decks and concrete barriers. A set of details for barrier-to-deck connections for accelerated bridge construction (ABC) applications are proposed. Component-level testing was carried out on a conventional cast-in-place (CIP) detail and two versions of connections using ultra-high-performance concrete (UHPC). The use of UHPC allows for shorter development length and lap splice length for dowel bars and the material characteristics provide strength and durability to the connection. Two connection details were proposed: (1) UHPC connection within the barrier segment (U-shape connection) and (2) UHPC connection in a recess inside the bridge deck (recessed connection). Besides simplified details, the construction sequence of the proposed recessed connection is suitable for ABC applications. It is observed that the proposed U-shape connection detail is emulative of the equivalent CIP concrete barrier system. However, the recessed connection system can undergo significantly larger deflections at ultimate load compared with the CIP barrier system and exhibits a preferred mode of failure while the deck does not undergo significant damage. The results of the component testing were used to calibrate non-linear finite element models. Using validated models, numerical analyses were performed to investigate the structural performance of conventional 15 ft long barrier modules connected to the deck overhang using the recessed connection. The model was subjected to the end-loading configuration and it was found that the proposed barrier system meets the strength requirement for the corresponding test level.

Cyclic load tests and finite element modeling of self-centering hollow-core FRP-concrete-steel bridge columns

This paper presents experimental and numerical investigations of the seismic performance of a novel self-centering (SC) hollow-core (HC) fiber-reinforced polymer (FRP)-concrete-steel (SC-HC-FCS) bridge column. This new structure is fabricated by mounting external energy dissipators (ED) and applying unbonded post-tensioned (PT) basalt FRP (BFRP) tendon to the conventional HC-FCS column that consists of an outer FRP tube and an inner steel tube, with the space between filled with concrete. The SC-HC-FCS column combines the advantages of accelerated bridge construction and self-centering. The effects of the initial prestress force values and the configuration of the energy-dissipated aluminum bar on the column performance are studied. Based on the experimental and numerical results, it is found that the proposed SC-HC-FCS column shows adequate self-centering and energy dissipation capacities. However, it is required to properly select the configuration and material properties of the aluminum bar as energy dissipators to further refine the seismic resistance of the SC-HC-FCS column.

Investigation of the Pier Response during the Lateral Slide of Multi-Span Bridges

Lateral slide-in bridge construction—also referred to as slide-in bridge construction (SIBC)—has gained increasing attention as a viable accelerated bridge construction (ABC) approach. Although SIBC has been successfully employed on multiple single-span bridge projects, the use of SIBC on multi-span bridges is rare. Adding more spans creates a more complex system that requires connections (and other details) that were previously not needed in a single-span slide. Also, it is a concern that the multi-span bridge would need to slide on piers, which creates possible uplift and overturning scenarios. As such, it was vitally important to understand the structural response of the substructure during the bridge sliding. Although much general information on lateral slides as an ABC method was available, very little literature had been published related explicitly to such construction for multi-span bridges. The objective of this research was to develop durable design details to be used with the lateral slide concept with a focus on pier connection details and evaluate the performance of the bridge pier during the sliding. To achieve the goal, relevant information was collected and evaluated by conducting a literature review on various details and construction approaches for previously completed lateral slide projects. Further, a three-span, 300 ft long steel girder bridge on IA 1 southwest of Iowa City, Iowa, U.S., was monitored using gauges during the slide-in. The results indicated that the current slide-in practice works well with the multi-span steel girder superstructure and the wall pier. No significant response from the substructure was visually observed during the slide-in, and no cracking occurred on the concrete deck or piers. This indicated that the superstructure with steel girders and concrete diaphragms could be built with the lateral slide-in method. The significant strain was measured from the pile strain gauges. However, the piles were functionally adequate to carry the vertical load, and the moment carried by each pile was minimal. An uplifting action was captured on Pier 1. However, this effect was minimal on Pier 2.

Structural Behavior of Bridge Deck Slabs Made with GFRP-Reinforced Lightweight Self-Consolidating Concrete

The use of lightweight self-consolidating concrete (LWSCC) has significantly increased due to enhanced mix designs and its projected lower overall costs than normal-weight concrete. Accelerated bridge construction (ABC) has become a common alternative to conventional construction techniques. The use of LWSCC in ABC will reduce structural loads and expedite transportation and installation of precast bridge elements. Limited research, however, has investigated LWSCC bridge elements reinforced with glass fiber–reinforced polymer (GFRP) bars. This paper reports on the performance of full-scale edge-restrained bridge deck slabs (simulating slab-on-girder bridges) fabricated with LWSCC reinforced with GFRP bars. The test specimens included three edge-restrained slabs and one unrestrained slab for comparison. The test specimens were 3,000 mm long × 2,500 mm wide × 200 mm thick and were tested up to failure under a concentrated load simulating the footprint of a standard CL-625 truck wheel load (87.5 kN) defined in current design codes. The investigated parameters were (1) reinforcement ratio; (2) top reinforcement; and (3) effect of edge-restraining. The cracking behavior, ultimate capacity, deflection, and concrete and reinforcement strains of the specimens were presented and discussed. In addition, the punching-shear capacity of the tested specimens was assessed with the currently recommended design equations. The test results indicate that the overall performance of LWSCC deck slabs reinforced with GFRP bars is similar to such structures made with normal-weight concrete.

Numerical Modeling of Column Piers with Recessed Spliced Sleeves and Intentional Debonding for Accelerated Bridge Construction

The grouted splice sleeve (GSS) connection is considered to be an effective bending moment–resisting connection between precast RC members. This connection type has been used extensively in nonseismic regions. The application of such a connection type in moderate or high seismic regions has been investigated and considered for multistory moment frame buildings and highway bridges. A computational modeling strategy is proposed at local and global levels for developing an appropriate computational model for such a connection type using a recessed GSS connection with intentional debonding. A computational model capable of predicting the structural response under cyclic loading was developed using established material models and a forced-based beam-column element considering low-cycle fatigue of reinforcing bars, bar-slip, intentional debonding of reinforcing bars, and plastic hinge length. The proposed model for recessed GSS connections with intentional debonding was experimentally validated. The proposed model was subsequently used to obtain the seismic response of a three-column bridge bent to near- and far-field earthquakes in terms of the overall maximum drift ratio and the drift ratio at the maximum seismic force.

Experimental study of CFST embedded precast concrete bridge column-foundation connection with studs

Accelerated bridge construction (ABC) is increasingly gained attention worldwide based on its advantage of high-quality precast elements, less environmental effect, quick construction speed, and minimum traffic block. The seismic performance of prefabricated bridge structures is mainly dependent on the feasibility of connections. To efficiently bear the load from the gravity of other elements and deformation ability in high seismic areas, in this study, an innovative contrete-filled steel tube (CFST) embedded precast concrete bridge column-foundation connection with studs was put forwards. Two 1:2 scale specimens were designed to verify the seismic performance of the proposed connection type. One is a precast specimen with the bridge column-foundation connection, the other is the conventional cast-in-place (CIP) specimen as a reference. The experimental observations and seismic properties were analyzed and compared with those of the CIP specimen, such as failure mode, load-displacement curves, energy dissipation, etc. The finite element model of the precast specimen with bridge column-foundation connection was established and the validated model was used to conduct the parametric study. The precast specimen with bridge column-foundation connection has a larger capacity, ductility, energy dissipation, and equivalent viscous damping ratio than the CIP specimen. Axial compression ratio, embedded depth, and concrete strength affect the seismic performance of the precast specimen with the bridge column-foundation connection. The proposed CFST embedded precast concrete bridge column-foundation connection can be applied to ABC technology in high seismic areas.

Numerical analysis and design method of UHPC grouted RC column- footing socket joints

Socket connection is an effective connection method for assembling precast columns and adjacent components in accelerate bridge construction(ABC). In order to further enhance the efficiency of this connection type, an extensive numerical study of reinforced concrete(RC) column-footing socket joints was conducted by experimental data. The force transmission mechanism, the influence of parameters on the strength and failure state of the socket joints are revealed. It was found that the socket depth, longitudinal rebar ratio and axial load ratio have notable effect on the mechanical performance of the socket joints compared with other parameters. Base on the numerical simulation and experimental results, a calculation method for the moment capacity of socket joints was developed, which can accurately predict the moment capacity and failure mode of RC column-footing joints with socket connections. A design method of RC column-footing socket joints was also given for practical engineering.

Analysis and design of mechanically spliced precast bridge columns

Reinforcement continuity in concrete members is traditionally achieved through lap splicing. An alternative is to use couplers to mechanically connect bars. Mechanical bar splices have been used in conventional and accelerated bridge construction (ABC) applications usually in capacity-protected and/or non-seismic members. Nevertheless, couplers are not currently allowed in the US national design codes to be used in the plastic hinge region of bridge columns in high seismic regions mostly due to uncertainty on their structural effects. This ban has also prevented the use of couplers as an ABC bent connection. A comprehensive analytical study was carried out to determine the effects of bar couplers on the RC bridge column seismic performance, specifically displacement capacities and demands. Modeling methods were proposed and validated against multiple test data. Subsequently, more than 950 pushover and nonlinear dynamic analyses were carried out on mechanically spliced circular and square bridge columns using the validated models. The results from the pushover analyses showed that couplers can reduce the columns displacement ductility capacity up to 45 %. A trend between the coupler length, rigidity, and the column displacement ductility capacity was established. Furthermore, the effect of couplers on the column displacement demands was found to be less than 10 % compared with unspliced columns. Finally, available design methods for mechanically spliced RC bridge columns were evaluated using test data for eight large-scale bridge columns.

Genetic Programming–Based Drift Ratio Limit Models for Segmental Posttensioned Precast Concrete Piers

Segmental posttensioned precast concrete (SPPC) is a promising approach to accelerated bridge construction (ABC). However, an impediment to the performance-based design of SPPC piers lies in the challenge of defining appropriate damage states and corresponding engineering demand parameter (EDP) limits. To address this, in this study, genetic programming (GP), a form of artificial intelligence, is used to develop drift ratio–based EDP limit models in order to identify the onset of four damage levels that are particularly introduced herein for SPPC piers. In this respect, a finite-element model using ABAQUS is developed and experimentally validated to simulate the response of SPPC piers under seismic loading. The model is then utilized to generate a data set of 316 cases, all within the feasible design space of SPPC piers. This data set is subsequently used to develop GP-based predictive equations that map the relationship between different SPPC pier design parameters (e.g., posttensioning strand ratio, concrete compressive strength, and gravity load level) and EDP (i.e., drift ratio) limits. The performance of the developed equations is evaluated through different measures, including fitness function and performance index. Ultimately, parametric and sensitivity analyses are conducted to demonstrate that the GP-based equations are robust enough to characterize the four damage states for SPPC piers.

Design Verification of a New Socket Partially Embedded Connection between Precast Rectangular Columns and Stepped Pile Caps

Socket connections are suggested to connect a precast column with adjacent members in accelerated bridge construction owing to their large construction tolerance. However, a typical socket-embedded connection always causes a heavy footing or pile cap due to the required embedment length, which is not preferable in the seismic design of a bridge system. In this paper, a new type of socket connection, namely, the partially embedded connection between a precast rectangular column and a stepped pile cap, is proposed to overcome this defect. Three half-scale specimens, that is, a cast-in-place specimen and two such designed socketed specimens with different step heights, were fabricated and tested to verify the new socket connection design concept. Experimental results showed that all specimens formed the approximate plastic hinges at the column bases and only minor damage occurred in the pile caps and the connecting regions; the hysteretic curves of the socketed specimens were approximately the same as that of the cast-in-place specimen, which proves that this new socket partially embedded connection is reliable to transfer the horizontal bending moment from columns to pile caps in a column–pile cap system and, meanwhile, can not only reduce the pile cap volume but also achieve the expected seismic performance.

Review of Accelerated Bridge Construction Systems for Bridge Superstructures and Their Adaptability for Cold Weather

The application of Accelerated Bridge Construction methods (ABC) to build, renovate and rehabilitate aging bridges is most likely to reduce the economic and social impacts of projects. This is especially relevant in countries with severe winter climates, where bridge construction is typically interrupted during the winter period. The objective of this study is to present the state of the art related to elements, systems, connections and materials used for bridge superstructures in ABC projects and to highlight their adaptability to cold or northern climate countries. The literature review and presentation of results are based on the gathering of Prefabricated/Precast Bridge Elements and Systems (PBES) used for ABC projects in North America and which are also used in many countries around the world. Following this inventory, and after grouping the PBES, connections and materials, the authors were able to identify the possibility of adapting the ABC method for countries with cold and northern climates. Products that can be used down to −6 °C for connections are presented, and future research orientations are proposed.

Shear performance of high-strength friction-grip bolted shear connector in prefabricated steel–UHPC composite beams: Finite element modelling and parametric study

As a competitive alternative for accelerated bridge construction (ABC), prefabricated steel–ultra-high-performance concrete (UHPC) composite beams containing high-strength friction-grip bolt (HSFGB) shear connectors offer numerous advantages, including reduced on-site construction time and ease of replacing/removing deteriorated components. However, the failure mechanism of HSFGBs in UHPC remains unclear due to the lack of internal stress analysis, which hinders the design of these innovative composite beams. To clarify the shear performance of HSFGBs in prefabricated steel–UHPC composite beams, an effective finite element model (FEM) considering the non-linearities of materials and geometry was developed through ABAQUS. Based on the experimentally verified model, the internal stress transfer mechanisms of HSFGBs and the failure mechanism of precast UHPC were revealed. According to the extension parametric analysis results, a stronger HSFGB presented better shear performances in terms of ultimate shear strength, initial shear stiffness and slip capacity. Adopting oversized holes with appropriate bolt-to-hole clearance can improve the constructional efficiency without considerable strength and stiffness reduction. HSFGBs with low bolt pretension exhibited unfavorable initial shear stiffness, while smaller slip capacity in high bolt pretension conditions. A smaller ductility was observed as the steel beam tensile strength and slab concrete strength increased. Additionally, the ACI 318–19, Eurocode 3, and AASHTO LRFD specifications underestimated the shear strength of HSFGBs, whereas the Eurocode 4 presented acceptable predictions in determining the ultimate shear capacity of HSFGBs in prefabricated steel–UHPC composite beams.

Effects of stud aspect ratio and cover thickness on push-out performance of thin full-depth precast UHPC slabs with grouped short studs: Experimental evaluation and design considerations

Steel-precast ultra-high-performance concrete (UHPC) composite beams containing grouped short studs in thin full-depth slabs are an economical and eco-friendly alternative for accelerated bridge construction (ABC). Nevertheless, there is limited information on the push-out performance of thin full-depth precast UHPC slabs with grouped short studs. To this end, this study examined the impacts of stud heights disturbing from 35 mm to 85 mm, stud diameters ranging from 16 mm to 22 mm, and cover thicknesses varying from 15 mm to 65 mm on the push-out performances of such members. The test results indicated that increases in stud height yielded insignificant enhancements in the shear stiffness, strength, and ductility of grouped short studs embedded in thin full-depth precast UHPC slabs. Similarly, variations in the stud height and cover thickness exerted negligible influence on the structural performance. Notwithstanding, larger cover thicknesses or larger stud diameters allow the stud to exhibit attractive shear behaviors. Based on these results, a lower limit of 1.84 for stud aspect ratios (i.e. the ratio of stud height to stud diameter) and 15 mm for cover thickness were recommended. Finally, more accurate formulas were developed to predict the shear capacity of studs by capturing weld collar contributions and to simulate the load-slip relationship of grouped short studs embedded in thin full-depth precast UHPC slabs by considering the effects of slab thickness.