Reinforced Concrete Deck Research Articles

Fatigue performance of ECC link slab incorporated full RC girder joint-free bridges

The use of link slab (LS) made of Engineered Cementitious Composite (ECC) in the construction of joint-free bridge deck can meet structural performance requirements and enhance durability to minimize life cycle costs. Studies documented in the literature to date have been limited to composite steel-concrete I-deck girder bridges despite their commonly used reinforced concrete (RC) girder counterparts in construction. This paper deals with two span full RC deck girder joint-free bridges with ECC link slab (ECC-LS) constructed and tested under static and fatigue loading up to 1,000,000 cycles at 4 Hz subjected to mean stress level of 40% of girder ultimate load, followed by post-fatigue static loading to failure. Residual load, deflection, moment, rotation, stiffness, and energy absorbing capacity of fatigued bridge specimens are compared with its virgin (non-fatigued) counterparts to assess structural performance. Experimental moment capacities are compared with those obtained from existing analytical equations. The comparative performance of joint-fee bridge with RC deck girder is compared with its composite steel-concrete I-girder counterpart to assess its feasibility of construction.

Experimental investigation of fatigue behavior of UHPFRC – RC composite deck slabs subjected to moving wheel loading

UHPFRC has been increasingly used as a bridge deck overlay material. Since bridge decks are exposed to severe mechanical action and harsh environmental conditions, the application of UHPFRC to bridge decks is an effective and wise utilization of UHPFRC’s excellent properties such as high strength and low permeability. This paper presents the result of a full-scale fatigue test of a reinforced concrete (RC) deck slab overlaid with UHPFRC (UHPFRC – RC composite deck slab) using a moving wheel load. The fatigue behavior of the UHPFRC – RC composite deck slab was analyzed using measurement data from the experimental test and discussed. The failure mode of the UHPFRC – RC composite deck slab was punching shear accompanied by near-interface concrete cracking and double curvature bending of the UHPFRC layer. The fatigue life of the UHPFRC – RC composite deck slab was estimated using an existing S-N relation of RC deck slabs subjected to moving wheel loads and a 30 mm thick UHPFRC overlay was found to increase the fatigue life of RC deck slabs by about five times.

Use of Geopolymer and Carbon Fiber-Reinforced Polymer for Repairing Reinforced Concrete Deck Soffit.

This study aimed to assess the feasibility of utilizing geopolymer for repairing reinforced concrete beams. Three types of beam specimens were fabricated: benchmark specimens without any grooves, rectangular-grooved beams, and square-grooved beams. The repair materials employed included geopolymer material, and epoxy resin mortar, while carbon fiber sheets were used as reinforcement in select cases. The repair materials were applied to the rectangular and square-grooved specimens, with the carbon fiber sheets attached to the tension side of the specimens. To evaluate the flexural strength of the concrete specimens, a third-point loading test was conducted. The test results indicated that the geopolymer exhibited higher compressive strength and shrinkage rate compared to the epoxy resin mortar. Furthermore, the specimens reinforced with carbon fiber sheets demonstrated even greater strength than the benchmark specimens. In terms of flexural strength under cyclic third-point loading tests, the carbon fiber-reinforced specimens exhibited the ability to withstand over 200 cycles of repeated loading at 0.8 times the ultimate load. In contrast, the benchmark specimens could only withstand seven cycles. These findings highlight that the use of carbon fiber sheets not only enhances compressive strength but also improves resistance to cyclic loading.

Salt-scaling resistance of highly durable RC slabs utilizing GGBS concrete with expansive additive

In recent years, the utilization expansive additive for ground granulated blast furnace slag (GGBS) concrete has been confirmed to be indispensable to reduce the early-age thermal tensile stress, which results in successful crack mitigation in several highly durable reinforced concrete (RC) slabs in Japan. However, various investigations have cited that the application of large amounts of expansive additive might reduce the salt-scaling resistance of durable RC slabs. This study experimentally investigates the salt-scaling resistance on the top surface of highly durable RC deck slab specimens by utilizing GGBS concrete with applicable dosages of expansive additive. Test results revealed that the proposed salt-scaling method modified based on ASTM C672 with a 6 h cycle and with more severe scaling temperatures at a minimum and maximum of ± 35 °C can reasonably reduce the experimental duration and effort for practical purposes. Moreover, although the salt-scaling resistance of the highly durable RC slab specimens decreased as the dosage of the expansive additive increased, acceptable salt-scaling resistance was obtained in the specimens with 20 and 25 kg/m3 expansive additive dosages.

Static and fatigue behaviour of ECC link slabs in reinforced concrete girder Joint-Free bridges

Engineered Cementitious Composite (ECC) has been recommended for application in bridge deck link slabs to minimize long-term life cycle costs through enhanced durability. However, ECC link slab experimental tests documented in the literature to date have been limited to steel superstructure, despite the use of reinforced concrete (RC) girders as common practice in bridge construction. RC deck girder isolated ECC link slab specimens were tested under static and fatigue load up to 400,000 and 1,000,000 cycles with mean fatigue stress level varied from 40% to 55% of ultimate load. The fatigue-damaged specimens were then statically loaded to failure. Residual load, deflection, moment, rotation, stiffness, and energy absorbing of fatigued link slab specimens were compared with virgin specimens to determine the level of deterioration. Experimental results were compared with those obtained from analytical calculations for reinforced concrete girder joint-free bridges with EC link slabs.

Early damage detection of fatigue failure for RC deck slabs under wheel load moving test using image analysis with artificial intelligence

Reinforced concrete (RC) bridge decks suffer from cracking damages caused by traffic loading and environmental-related defects, such as the alkali-silica reaction (ASR). These require inspections involving measuring crack width and density followed by essential maintenance and repair works, however, there are no signs for fatigue failure. In this study, the out-of-plane shear deformations which cause small delaminations (pits) along surface cracks are proposed as an early indicator for fatigue failure. Thus, un-damaged and ASR-damaged RC deck slabs are tested under moving wheel loading and, using image-recognition for surface cracks detection, the pits along surface cracks are captured using an artificial intelligence (AI) model. The results show that, while both crack and pit density increase over the fatigue life of un-damaged slabs, there is an earlier sudden increase in pit density. In the case of the ASR-damaged slab, surface cracking is almost constant over the fatigue life until a sudden increase just prior to failure. Pit density, however, increases over the fatigue life with an earlier rapid increase before failure. The density of pits along cracks would be, therefore, a significantly earlier indicator of fatigue failure than crack density, offering the potential for more efficient and automatable bridge inspections.

Full-scale fatigue simulation of the deterioration mechanism of reinforced concrete road bridge slabs under dry and wet conditions

This study investigates the deterioration process and mechanism of reinforced concrete (RC) slabs in road bridges under dry and stagnant water (wet) conditions. Previous studies used a simple-plate model (SPM) to predict the fatigue life of RC decks by considering conservative assumptions for safer assessment under different environmental processes. To obtain a more detailed analysis and clarify the deterioration result and mechanism, a full-scale superstructure of a realistic bridge is used in this study. The simulation results reveal differences between the full-scale model (FSM) and SPM due to size effects and boundary conditions. The findings also demonstrate that the failure mechanism in the FSM simulations differs between dry and wet conditions. In dry cases, damage easily occurs at the bottom surface of the bridge slab. However, in wet cases, horizontal cracks and disintegration occur below the top surface near the upper rebar layer of the slab during the early stage over a very short time period, which cannot be visually investigated according to current bridge slab inspection regulations. These results successfully reproduce the deterioration phenomenon that occurred on site, which indicates the credibility of the simulation. Then the effect of two wheel-loading on RC slabs is studied to assess the slab continuity at adjacent panels. This study provides a useful reference for more rational design and maintenance of RC slabs of road bridges.

A Comparison between Ultrasonic Guided Wave Leakage and Half-Cell Potential Methods in Detection of Corrosion in Reinforced Concrete Decks

This article presents the advantages and limitations of a recently developed Ultrasonic Guided Wave Leakage (UGWL) method in comparison to the well-known Half-Cell Potential (HCP) method in their ability to detect corrosion in reinforced concrete (RC) bridge decks. This research also establishes a correlation between UGWL data and chloride content in concrete RC slabs. Concrete slabs submerged in a 10% NaCl solution were monitored using both methods over a period of six months. The chloride content from the three cores (0.84, 0.55, and 0.18%) extracted from the slab after the 6-month long process all exceeded the chloride threshold values suggested in ACI 318, which is 0.05 to 0.1% by weight of concrete. Further, the UGWL method detected changes due to corrosion approximately 21 days earlier than the HCP method.

Strengthening of defected closure strips for full-depth RC deck slabs using CFRP sheets

Two configurations of closure strips between precast reinforced concrete (RC) slab panels were fabricated and filled with either non-shrink grout or ultrahigh-performance strain-hardening cementitious composite (UHP-SHCC) material. The strips were then strengthened with externally bonded carbon-fibre-reinforced polymer (CFRP) sheets in order to compensate the drawback associated with decreasing the amount of connected steel reinforcing bars required to transfer the bending moment between panels. In total, 12 specimens divided into three groups were cast and tested under short-term non-reversed repeated patch loads simulating wheel load at the central joint. The test results showed that the UHP-SHCC filling material enabled the connected panels to exhibit more ductile behaviour compared with the panels whose closure strips were filled with non-shrink grout. On the other hand, the CFRP strengthening sheets for the first configuration of the closure strip failed to restore the ultimate capacity of the un-strengthened monolithic specimen. However, the second configuration, using UHP-SHCC filling material, enabled the connecting panels to restore lost capacity, with a performance improvement of about 14% compared with the un-strengthened monolithic specimen.

Structural condition assessment of reinforced-concrete bridges based on acoustic emission and strain measurements

A reliable novel monitoring approach is developed to assess the structural condition of reinforced-concrete bridge elements. The approach is based on combining acoustic emission technique and strain gauge measurements, and it is illustrated by a case study of a composite steel–concrete viaduct in service since 1957. Monitoring was performed on its reinforced-concrete deck slab under traffic and environmental loading for one year. The monitoring setup and procedure are presented. The variation of acoustic emission signals is evaluated regarding strain and temperature measurements. Parametric study, pencil-break test, statistical analysis, crack classification and b-value analysis are performed to assess the structural condition. The acoustic emission activity of the reinforced-concrete slab is evaluated for 1 year under operational conditions. From the monitoring approach, it was possible to identify the nature of the cracking activity in the concrete slab as a function of traffic loading and temperature and to assess in time the condition of the slab-girder connection.

Effects of Redecking from RC Deck to Orthotropic Steel Deck on Seismic Resistance of Elevated Girder Bridges

Due to the rapid deterioration of reinforced concrete decks (RCD) under the combined effects of deck overloads, weather and salts, the orthotropic steel decks (OSD) that are light weight and require less construction time are being used increasingly to replace old deteriorated decks. In this paper, a numerical investigation was carried out to study the effect of reduction in superstructure weight on the earthquake resistance of elevated girder bridges when an existing RCD was being replaced by an OSD. Firstly, an eigenvalue analysis was carried out to study the effect of superstructure weight on the global vibrational characteristics of the bridge and then, the evaluation of seismic performances of both the bridge models were carried out by performing a series of non-linear dynamic analysis with input earthquake data in the longitudinal and transverse directions separately and simultaneously. The behavior of the pier bases was examined by monitoring the displacement responses and plastic strains during earthquakes. It was found that the bridge model with OSD exhibits a shorter period of vibrations and a huge improvement in the seismic performance of the bridge was observed by replacing the existing RCD with the OSD. The analysis results could be useful in finding a solution for seismic retrofit of existing girder bridges.

The Optimum Reinforced Concrete Deck Stiffness of Cable-Stayed Bridge Decks

This paper aims to find optimum deck stiffness and optimum girder profile in terms of vertical deformation and cable stresses. The feasibility of this study was achieved by analyse and develop eighteen models twice using ABAQUS software; six different deck stiffness and three different girder profile. A nonlinear static finite element analysis was performed on the previous models. The results show that the maximum stress found at maximum deck stiffness and the maximum cable stress found at maximum girder cross section. Also, the deflection decreased dramatically with the increase of deck stiffness. Therefore, the relationship between the vertical displacement and deck stiffness is inverse. Referring to the data obtained and collected from these analytical models the concrete deck slab with 50 MPa grade is the optimum grade in terms of strength and serviceability requirements.

Quantification of traffic and temperature effects on the fatigue safety of a reinforced-concrete bridge deck based on monitoring data

For assessment of existing reinforced-concrete bridges, only few rules and recommendations are available, and engineers meanwhile apply design codes for new bridges to evaluate the fatigue safety of existing bridges leading to non-realistic approaches and conclusions. Design codes for new structures are often based on the worst scenarios, and they are not made to assess existing structures with specific loadings and material properties. Direct monitoring provides an important source of information about the actual structural loading and response. This article presents an integral approach to identify fatigue damage of a reinforced-concrete deck as a function of the relevant actions for fatigue using monitoring data. This includes a long-term monitoring system to measure strain and temperature in the most loaded parts, an inverse method using monitoring data to reconstruct traffic actions from the structural response, and a simulation of traffic loading and its effects using a compiler and a finite element model to estimate fatigue damage. The presented approach can be used as a base on how to monitor and analyze recorded data to evaluate the fatigue safety of existing reinforced-concrete slabs in road bridges.

Effect of Crack Orientation on Fatigue Life of Reinforced Concrete Bridge Decks

In visual inspection of bridges at sites, much attention is given to the density and width of cracks of concrete, but little attention is paid to crack orientation for the diagnosis of bridge performance. In this research, the effect of crack orientation on the remaining fatigue life of reinforced concrete (RC) bridge decks is investigated for crack patterns with a wide range of possible crack orientations. The data assimilation technology of multi-scale simulation and the pseudo-cracking method, which are widely validated for fatigue-lifetime simulation, are utilized in this study. The impact of the crack direction on fatigue life is found to be associated with the coupled flexure-shear mode of failure, and the mechanism to arrest shear cracking by preceding cracks is quantitatively estimated. This mechanism is similar to the stop-hole to prevent fatigue cracks in steel structures, and it enables us to enhance the fatigue life of RC decks. It is demonstrated that the crack orientations that approximate the longitudinal and transverse directions of RC decks are the ones that most extend remaining fatigue life. Finally, the higher risk cracking locations on the bottom surface of RC decks are discussed, presenting information of use to site inspectors.

Fatigue Life of RC Bridge Decks Affected by Non-Uniformly Dispersed Stagnant Water

Stagnant water on reinforced concrete (RC) decks reduces their life significantly compared to the case of dry states. Fully submerged states have been investigated as the most severe case, which is however rarely experienced in reality. Currently, it is possible to simulate concrete–water interactions for lifetime prediction of RC decks. In this study, fatigue lifetime is systematically computed for various locations of stagnant water at the upper layer of RC decks. It is found that the patterns of wet and dry areas have a great influence on the remaining fatigue life even though the same magnitude of cracking develops. Then, a hazard map for the wetting locations with regard to the remaining fatigue life is presented based on the systematically arranged simulation. Finally, a nonlinear correlation is introduced for fatigue life prediction based upon site inspected wetting locations, which can be detected by non-destructive testing technology.

Novel Application of PVDF Sensors for Vehicle Weight Identification in Reinforced Concrete Deck Steel Bridges

Novel Application of PVDF Sensors for Vehicle Weight Identification in Reinforced Concrete Deck Steel Bridges

Experimental Research on Prestressed Carbon Fiber Reinforced Plastic Reinforced Concrete Decks

A new type of bridge deck structure with prestressed Carbon Fiber Reinforced Plastic Reinforced (CFRP) tendons was designed. Flexural performance tests on the prestressed concrete bridge deck with CFRP tendons were conducted. The cracking and ultimate loads of such bridge deck and the stress states and failure modes of the CFRP tendons were systematically analyzed. Results showed that the bending force process of unbonded prestressed CFRP tendon bridge deck with ordinary steel bars in the tension zone can be divided into three stages, namely, initial elastic loading state, elastic-plastic stage from the appearance of cracks to ordinary steel yielding in the tensile area, and rapid deformation development and destruction stage during tension bearing of the CFRP tendons. The failure modes of unbonded prestressed CFRP tendon bridge deck were caused by the rapid deformation development due to the low modulus of CFRP tendons, and the extension of cracks and crushing failure of concrete were due to the decreased area of effective compressive concrete. The fractures were mostly equidistant parallel cracks. The cracks slowly developed in the early stage, whereas they rapidly developed after ordinary steel yielding.

Damage detection method for RC members using local vibration testing

A portable vibrator was used to conduct forced vibration testing of concrete members to determine damage locations and conditions within structural concrete. In particular, a local vibration testing method was proposed, along with a numerical means for characterizing the test results. In reinforced concrete (RC) beam specimens with a void, the local resonant frequency decreased over the void region as its length increased. This implies that the void locations and conditions can be identified from the resonant frequency distribution obtained from local vibration testing. Furthermore, in RC beam specimens reinforced with carbon fiber sheets, internal voids can be also identified using the testing method, even though one face of the RC member is covered with the sheets.From the experimental data, the effective region of the local vibration testing is approximately equal to the sectional height. The wave propagation analyses were conducted using a finite difference time domain (FDTD) method, and a simple local calculation model was proposed. Through comparisons with the experimental results, it is shown that the local model can estimate void location and length with good accuracy. From statistical comparisons between the experimental and calculated resonant frequencies, in the intact regions, the mean value of the resonant frequency ratio and its coefficient of variation were 1.03 and 2.8%, respectively. These low values demonstrate the accuracies of both experimental testing method and simple calculation model. On the other hand, in the void region, these values were 0.97 and 17.5%, respectively.As a practical example, the local vibration tests were conducted on a portion of a deteriorated RC deck, which was removed from a bridge structure. In the tests, it was shown that the local resonant frequency is decreased by horizontal cracking within the deck section. Moreover, the resonant frequency distribution of the removed deck was determined. The coefficient of variation of the resonant frequency in intact regions was 5.2%, which is not far from the value (2.8%) obtained for the cast specimens. This indicates that the proposed testing method can be applied for the detection of damage within RC decks.

Finite element modelling of demountable precast reinforced concrete deck slabs with external confining system

This paper investigates the enhanced loading capacity and structural behaviour of a transversely confined precast reinforced concrete (RC) deck slab with deconstructable post-installedfriction-grip bolted (PFGB) shear connectors. A detailed 3D non-linearcontinuum-based finite element (FE) model of the deconstructable composite deck with external confining systems (i.e. cross-bracings or ties) and PFGB shear connectors is developed and analysed using the commercial software ABAQUS. The non-linearity of the contacts/interfaces, geometrical and material non-linearities are considered in the FE models. The developed FE models are validated against experimental results and it is shown that the proposed FE model can adequately predict the enhancing effect of arching action in a transversely confined deconstructable precast RC deck slab. Lastly, a parametric study is carried out and effect of different parameters such as compressive strength of concrete, yield strength and proportion of reinforcing bars, clearance between concrete slab and PFGB shear connectors and pretension stress in the PFGB shear connectors on the stiffness and strength enhancement provided by the arching action are evaluated and discussed.

Quantitative Evaluation of Risk Factors Affecting the Deterioration of RC Deck Slab Components in East Japan and Tokyo Regions Using Survival Analysis

The investigation described in this paper aims to determine the factors in the deterioration of reinforced concrete (RC) bridge deck slab components, quantitatively evaluate them using survival analysis, and thus facilitate optimal decision-making. To consider bridge deterioration across Japan, bridge inspection data from the East Japan and Tokyo regions were selected based on their different deterioration phenomena and processes. Data cleaning and selection were conducted to increase the accuracy and reliability of the analysis. Using the Kaplan–Meier (KM) estimator and Cox multivariate regression model, the hazard risk of each variate was quantitatively estimated. For East Japan, winter precipitation and de-icing salt greatly increased the deterioration rate, indicating that high humidity and a high salinity environment were the main reasons for deterioration. However, for the Tokyo region, traffic loading resulted in high risk, indicating that fatigue failure was the main risk factor. In both areas, the slab edge showed a high deterioration rate; therefore, edge waterproofing should be improved to enhance durability. Additionally, the risk score of each bridge component was calculated and mapped using geographical coordinate information. Inspection, repairs, and rehabilitation can be more efficiently conducted using this information.