Slab Bridge Research Articles

Effect of blast load on the structural integrity of steel arch bridge slab

In order to know the safety margins and the critical zone of an important infrastructure such as a bridge, the response of the construction typology to extreme forces must be investigated. In this sense, in the literature, few numerical and experimental data are available concerning the response of steel bridges under explosive loads. The purpose of this work is to develop a coherent model, using the finite element analysis method, to verify the behaviour of such a structure and to focus on the collapse mechanism. As a case study, a typical network arch bridge was defined and meshed. Information about stresses, strains and displacement were collected as a function of the position and intensity of the slab damage. Finally, some useful observations were collected regarding the slab response, damage mechanisms and the role of the concrete class.

Research of strength and condition of cement-concrete pavement on bridges by non-destructive methods

The article presents the results of determining the strength of non-destructive methods of cement concrete pavement on bridges. According to the results of the research, a differential curve, a reliability curve and the inverse value of the accumulated frequency of compressive strength of cement concrete are constructed. It is established that the cement concrete of the investigated objects corresponds to the strength class according to the normative documents. However, the results of visual, instrumental and thermal imaging inspection of areas on the bridges revealed a number of defects in the cement-concrete pavement and pavement slabs, which can lead to loss of the pavement structure strength. In particular, it was found that the destruction of the inspected reinforced concrete slabs of bridges mainly occurs under the influence of corrosion and loss of the working part volume of the steel reinforcement, unsatisfactory condition of the compensation seams on the supports. It is determined that cracks in reinforced concrete slabs occur due to low resistance of concrete to bending loads, due to which steel reinforcement is exposed to aggressive environments. In turn, it was proved that structural cracks in concrete occurred due to excessive loading, which led to overstrain of the structure, and non-structural cracks - due to internal stresses caused by thermal loads and various linear expansions of materials. Thermal imaging study revealed a significant difference in temperature in the pavement structural elements, which in the future leads to the destruction of cement-concrete pavement. It was found that the peeling of the protective layer of metal reinforcement on the studied bridges is caused by the phenomenon of electro-chemical corrosion.
 The experience analysis of cement-concrete pavement of the studied objects allows to prepare proposals for the construction of cement-concrete pavement of bridges and overpasses using modern materials, in particular, non-metallic reinforcement.

Fatigue Performance of Rib Beam Bridge Slabs Reinforced with Polyurethane Concrete Based on the Damage Theory

In this paper, the rib beam bridge slabs were taken as the research object. Static load and fatigue tests were carried out on the benchmark bridge slabs to determine the ultimate load capacity and fatigue life of the bridge slabs. Then, the bridge slab was pre-damaged and reinforced with polyurethane concrete. A fatigue test was carried out on the reinforced bridge slab to study the fatigue performance. Based on the damage theory, the fatigue damage reinforcement finite element models of the bridge slabs under different damage degrees were established. The fatigue performance of the reinforced bridge slabs was systematically studied. The results show that the fatigue damage of the reinforced bridge slab developed in stages. Compared to the unreinforced bridge slab, the fatigue damage of the reinforced bridge slab was significantly reduced at each stage. According to the least square method and numerical analysis results, a residual-bearing-capacity model including damage degree and fatigue cycles of the reinforced bridge slabs is proposed, which can be used as a reference in bridge slab reinforcement design.

Estimating the Load Rating of Reinforced Concrete Slab Bridges Without Plans

This article documents the development of a multiple regression model for the estimation of the inventory rating of reinforced concrete slab bridges. Given the lack of information on the superstructure elements in the National Bridge Inventory, the authors developed a data set by using the information found in as-built drawings provided by multiple state departments of transportation. The data consisted of 50 reinforced concrete slabs for which their inventory rating was computed. Various model combinations were considered, and their estimated errors were evaluated by performing a repeated tenfold cross validation. A five-variable model that included the year built, the span length, the slab thickness, the support type, and the skew was selected based on the lowest mean error and variance. The model had an adjusted coefficient of determination (adjusted R2) of 0.817, which was considerably higher than a previously developed model. The difference in adjusted R2 is attributed to the inclusion of slab thickness as an independent variable as well as to the quality of the data used.

Multifractal analytical method and experimental study on crack evolution of dismantled RC hollow-slab beam

Reinforced concrete is the earliest and most commonly used bridge construction material and there are a large number of RC bridges in service all over the world. Due to a long-time operation and external load, most concrete bridges suffer from various degrees of damage. The most common method used in the maintenance of these bridges is visual inspection, which is highly subjective, lacks quantitative means and provides little information about the mechanical properties of the structure. Therefore, this paper conducts a set of failure experiment of the reinforced concrete hollow slab beams based on multifractal theory, and then proposes a convenient damage detection method for reinforced concrete beam bridges based on crack distribution images. Firstly, this paper introduces the basis of multifractal theory and an example of its application to the cracking characteristics of concrete beam members. Then a set of failure experiment on demolished members of in-service reinforced concrete hollow slab bridges was conducted, and two high-precision industrial cameras were used to record the full process of crack development on the surface of the beams. Then the multifractal theory was used to quantitatively characterize the crack distribution characteristics of the beams during the load process. The function relationship between the fractal dimension and the bending moment and the main mechanical properties (mid-span deflection, maximum crack width) of the test beam was analyzed and the damage index based on fractal dimension is calculated. The results show that the multifractal theory performs appropriate in describing the crack distribution of the beam, the points on the multifractal spectrum continuously move to larger values as the bending moment increases, and the generalized fractal dimension values have similar conclusions. The functional correlation between main mechanical properties and the fractal dimension is strong. Based on the experiment results, the damage classification criteria for reinforced concrete bridges are proposed referred to the IAEA guidelines. Three damage classes and corresponding the range of values of fractal dimension (FD) and the damage index (DI) are given. These findings provide a useful tool for exploring the cracking performance and rapid detection of reinforced concrete bridges.

Research on Widening Design Methods of Old Hollow Slab Bridges

Research on Widening Design Methods of Old Hollow Slab Bridges

The effect of soil improvement and auxiliary rails at railway track transition zones

Railway track transition zones are areas where there is a sudden change in the track-ground structure. They include changes between ballasted and slab track, bridge approaches, and tunnel entry/exits. They are often the location of rapid track deterioration, and therefore this paper investigates the use of auxiliary rails and soil improvement to minimise train-track-ground dynamic effects. To do so, a 3D finite element model is developed using eight-node solid elements and a perfectly matched layer absorbing boundary condition. A moving train load is simulated using a sprung mass model to represent train-track interaction. After presenting the model, it is validated against field data collected on both a plain line and at a transition zone. Once validated, a sensitivity study is performed into auxiliary rails and soil improvement. It is found that auxiliary rails can improve the dynamic characteristics of the track across the transition, and that more widely spaced auxiliary rails provide greater benefit compared to closely spaced ones. Regarding soil improvement, a large benefit is found, and for the material properties under investigation, the effect of soil stiffening is greater than using auxiliary rails.

Quantification of influence of monitoring duration on measured traffic action effects on fatigue of RC deck slabs of road bridges

The safety of existing bridges may be assessed using data from monitoring. The fatigue damage induced during observation period is extrapolated to the total service duration of a structure, and the reserve capacity is estimated. However, due to the randomness of road traffic, there exists a risk of underestimation of damage using a short-term monitoring campaign. This paper analyses the influence of monitoring duration on the obtained results using datasets collected during two long-term (>3 years) dynamic monitoring campaigns. Two road bridges with different nature of traffic are considered: (a) a heavily loaded two-lane highway viaduct and (b) a road viaduct with a bi-directional traffic. The deck slabs of both bridges are monitored using strain gauges installed on reinforcement bars. The daily, seasonal, year-to-year and COVID-19 lockdown-induced variations of measured action effects and calculated equivalent fatigue damage are discussed. The resampling method is used for simulation of possible short-term monitoring campaigns during the period considered, with different order of heavy vehicles arriving. The Extreme Value Theory serves to answer what is the required monitoring duration for reliable results. Possible ways of considering the monitoring duration in the fatigue damage calculation are discussed, and the methodology for damage extrapolation proposed.

Push-out tests on studs with UHPC cover embedded in UHPC-NSC composite slab

To cope with the volumetric cost of the ultra-high-performance concrete (UHPC) and enhance performance of studs in steel–concrete composite bridges, a novel bridge slab system has been developed. In this system, the slab was made of UHPC and normal strength concrete (NSC), and the studs were covered with UHPC. Since the static behavior of studs with UHPC cover embedded in UHPC-NSC composite slab is different from in the NSC or UHPC slab, an experimental study is needed to investigate the ultimate strength of studs, as well as the relative slip and failure patterns. The mainly parameters considered include stud diameter, stud height, and stud root with or without UHPC cover. The experimental results reveal that the mechanical behavior of studs in the proposed composite slab system was successfully improved. The ultimate strengths of the studs with a diameter of 19 mm and 22 mm covered with UHPC embedded in UHPC-NSC composite slab are only 3.8 % and 2 % less than that in UHPC slab, respectively. The relative slips of stud with UHPC cover in the UHPC-NSC composite slab are larger than 6 mm, which satisfy the ductility demand in EC4. The results also show that the current design codes underestimate the actual shear strength of the stud with UHPC cover in the UHPC-NSC composite slab. Finally, an equation is proposed to predict the shear stiffness of a stud with UHPC cover embedded in the UHPC-NSC composite slab based on the energy equivalent model, and verified by the experimental results. The calculation value agrees well with the experimental result for a stud diameter≥16 mm.

Determining Orders of Modes Sensitive to Hinge Joint Damage in Assembled Hollow Slab Bridges

Determining Orders of Modes Sensitive to Hinge Joint Damage in Assembled Hollow Slab Bridges

Full-range Experimental Analysis of Flexural Performance of an Existing PC Hollow Slab

Prestressed concrete (PC) hollow slab bridges are the most common type of short and medium span highway bridges in China. With the increasing load and environmental degradation factor, the flexural capacity of hollow slab bridges in service for many years can no longer meet the new safety regulations. Further research on the flexural capacity of these hollow slabs is necessary to ensure their safety. Experiments on the flexural bearing capacity of a full-scale damaged PC hollow slab are conducted. Elastic, cracking, re-cracking, and destruction tests are conducted to determine the deflection, strain, crack width, bearing capacity, stiffness, failure mechanisms, and dynamic characteristics of the slab. The strain measurements of the steel bar and prestressing tendons in the four-stage bending test indicate new failure characteristics of the PC hollow slab. After the steel bar yields, the concrete stress is redistributed, and the concrete on the top of the hollow slab exhibits tension, compression, and shear, providing science-based information to improve the ultimate bearing capacity of the slab. The cracking load (ultimate load) obtained from the full-scale bending test is 23% (72%) higher than the design value of the main slab’s internal force in normal service limit state (loading capacity limit state). The ultimate displacement in the midspan of the slab is 1/47 of the calculated span length, and the slab exhibits ductile failure characteristics, indicating very good ductility and sufficient strength of the slab after a 23-year service life. This study can provide a reference for the safety assessment and maintenance of numerous hollow slab bridges that have been in service for many years in China.

Detecting Hinge Joint Damage in Hollow Slab Bridges Using Mode Shapes Extracted from Vehicle Response

AbstractHinge joint damage is the main defect affecting the safety of assembled hollow slab bridges. The timely discovery of hinge joint damage is significant for guaranteeing the structural safety...

Demountable Bolted Shear Connector for Easy Deconstruction and Reconstruction of Concrete Slabs in Steel–Concrete Bridges

Welded headed studs are used to connect steel girders and concrete slabs in steel composite bridges. However, environmental problems related to welded shear connectors have been reported, including noise and dust generation during the replacement and demolition of damaged or worn concrete slabs. To overcome these issues, demountable shear connectors that enable easy replacement of damaged or worn concrete slabs must be developed. However, conventional bolted shear connectors mainly use embedded nuts, which cannot be used in structures such as bridges because initial slip occurs and the stiffness and shear resistance strength are relatively low. To address these issues, this paper proposes a bolted shear connector that integrates the embedded nut part into the stud bolt and has a tapered shape at the bottom of the expansion column. For performance verification in regard to static shear strength and slip displacement, push-out tests were performed according to Eurocode-4, and the performance of the proposed stud bolt was compared to those of conventional welded headed studs and embedded nut-style bolted shear connectors. In addition, an analytical review was performed using the ABAQUS program for the 1/4 axisymmetric model of the push-out test. As a result of applying the material nonlinear model and the surface contact analysis, the load-slip displacement of each analysis model showed a tendency extremely similar to the experimental results. The proposed demountable bolted shear connector exhibited excellent shear performance and can be used as a satisfactory replacement for conventional welded studs because it meets slip displacement and ductility standards.

Flexural Analysis Combined with Freeze-thaw Depth for Reinforced Concrete Beams and Columns

This study presents a kinematic model for flexural analysis of RC beams and columns subjected to freeze-thaw action based on upper bound theorem. The developed model enables analytical derivation of the contribution of damaged concrete when actual deterioration profile is idealized as an assemblage of undamaged and damaged zones based on freeze-thaw depth obtained from concrete core specimens. The accuracy of the analysis is verified by comparing its predictions with available 21 RC columns and beams failing in flexure after freeze-thaw exposure. The predicted results show good agreement with the test results within error of 6% on average. Thereafter, the developed analysis predicts the ultimate moment capacity of a RC beam, which was taken from an existing bridge slab replaced because of the combined effect of frost damage and fatigue. Results demonstrate that the present analysis could support a rational decision-making regarding the need for repair or rehabilitation. This paper is the English translation from the authors’ previous work [Kanazawa, T., Nakamura, T., Sakaguchi, J. and Kawaguchi, K., (2021). “Flexural analysis combined with freeze–thaw depth for RC linear members.” Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures), 77(4), 177-186. (in Japanese)].

Validation of a method for estimating the extent of segregation on bridge slab using ground penetrating radar with deep learning

Validation of a method for estimating the extent of segregation on bridge slab using ground penetrating radar with deep learning

Shear strengthening of concrete T-beams with lateral layers of UHPC

Concrete T-beams are commonly used in building slab systems and bridge decks. They may require strengthening in shear when they are deteriorated or when loading requirements increased. This research project studied the shear behaviour of concrete T-beams using cast-in-place Ultra High-Performance Concrete (UHPC) layers as a lateral strengthening method avoiding beam depth modification. Three UHPC strengthened beams together with one reference reinforced concrete beam were tested in monotonic three-point bending. Parameters investigated include the thickness of UHPC layers and the presence of steel anchors at the UHPC-concrete interface. A digital image correlation (DIC) technique was used to investigate the strain distribution of T-beams during the testing. Strain distribution, failure modes and strengthening effects provided by the UHPC lateral strengthening were analyzed. Results show that UHPC strengthening can substantially improve the stiffness and shear capacity of concrete T-beams, 25 and 50 mm lateral layers increased by 102% and 113% the T-beam shear capacity, respectively. Typical bending-shear behaviour were observed on each strengthened beam with UHPC layers. A final shear failure was observed in the T-beam with 25 mm UHPC layers and 50 mm UHPC layers without anchors, while a combination of shear and bending failure was noted in the T-beam with 50 mm UHPC layers and steel anchors. The steel anchors at the UHPC-concrete interface can further increase the ultimate shear capacity and beam stiffness, but at a limited extent. Therefore, experimental results confirmed that cast-in-place UHPC lateral layers are an effective way to strengthen existing concrete T-beams with inadequate shear capacity

Repair effect and ultimate load-carrying capacity of reinforced concrete beams with steel plate bonding quarried from existing bridge slabs by re-injection of resin

Repair effect and ultimate load-carrying capacity of reinforced concrete beams with steel plate bonding quarried from existing bridge slabs by re-injection of resin

Corrosion-Fatigue Life Prediction Modeling for RC Structures under Coupled Carbonation and Repeated Loading

The coupled action of concrete carbonation and repeated loading strongly influences the safety of reinforced concrete (RC) structures and substantially reduces service life. A novel corrosion-fatigue life prediction model for RC structures under coupled carbonation and repeated loading was developed. The effect of fatigue damage on concrete carbonation and carbonation-induced corrosion rate was considered, and the acceleration of fatigue damage accumulation due to reinforcement corrosion was considered in this approach. The proposed corrosion-fatigue life prediction model was illustrated by a 6 m-span RC slab in a simply supported slab bridge for the highway, and the effects of traffic frequency, overloading, carbonation environment grade, and environmental temperature and relative humidity on corrosion-fatigue life were discussed. The results indicate that the proposed model can predict the corrosion-fatigue life of RC structures simply and conveniently. Traffic frequency, overloading, carbonation environment grade, and environmental temperature and relative humidity can decrease the corrosion-fatigue life of the RC slab by up to 66.86%, 58.90%, 77.45%, and 44.95%, respectively. The research is expected to provide a framework for the corrosion-fatigue life prediction of RC structures under coupled carbonation and repeated loading.

Strengthening of fatigue cracks in steel bridges by means of adhesively bonded steel patches

ABSTRACT Steel bridges with orthotropic decks are a common construction method for long-span bridges. The type of construction was developed in the 1960s, and the early structures in particular show increasing crack damage. The reasons for this are, on the one hand, design deficiencies and, on the other hand, massively increased traffic loads. Therefore, there is a need for rehabilitation methods that neither weaken the cross-section, like bolted solutions, nor introduce thermal stresses, like welds, but so far there are no reliable and economic alternatives. This paper summarizes the state of the art on possible damage categories of orthotropic bridge slabs and presents a new rehabilitation alternative using bonded steel patches for crack rehabilitation. It is reported from an ongoing research project how to determine numerically the effectiveness of the bonded steel patches. For this purpose, simple analytical calculations are first used to determine the determining factors and to record their influence. Subsequently, nonlinear numerical calculations with the Drucker-Prager material model are used to identify the stress distributions in the bonded joints in order to optimise the patch geometries. To this end a stiffness factor is presented that can be used to classify such patch bonds and categorize them in terms of their effectiveness.

Fatigue durability of reinforced concrete bridge deck repair methods

In recent years, the aging of existing reinforced concrete deck slabs of road bridges in Japan has been attributed to the deterioration of the concrete on the upper surface, and partial replacements have been carried out as a measure to extend service life. This study comparatively verifies the effectiveness of the partial cross-section replacement method, using a wheel load running test and focusing on the combination of the removal method of the existing concrete and the repair material. An appropriate method of partial replacement of existing reinforced concrete deck slabs is also proposed.