Bridge Deck Slabs Research Articles

Impact of sulfate damage on the behavior of full-scale concrete bridge deck slabs reinforced with FRP bars

This paper is aimed to analyze the performance of reinforced-with-FRP, sulfate-damaged concrete bridge deck slabs under concentrated loads, using the nonlinear finite element analysis (NLFEA) method. For experimentation purposes, twenty-seven full-scale models have been prepared to simulate concrete bridge deck slabs, with a length of 3000 mm and a width of 2500 mm. The parameters of the study were: (i) type of reinforcement, as three types were tested: glass FRP (GFRP), carbon FRP (CFRP), and steel; (ii) bottom transverse reinforcement ratio (ρ = 0.38, 0.46, and 0.57); and (iii) sulfate damage level, which consisted of three levels: Level 0 (undamaged), level 1 (73 days), and level 2 (123 days). All of the slabs models were equipped with two parallel girders of steel as supporters. To be able to analyze the models' performance up till failure, the load exerted by sustained truck wheels (87.5 kN CL-625 truck) was simulated by subjecting each slab model to a monotonic single concentrated load, with a contact area of 600 × 250 mm, at the center of the models. The simulated models encountered a punching shear mode of failure. The analysis showed that the models that were strengthened with CFRP and GFRP bars exhibited a remarkable improvement in the models': ultimate load, elastic stiffness, post-cracking stiffness, elastic energy absorption, and post-cracking energy; whereas, there was less influence on the models' ultimate deflection, compared to the ones strengthened with steel.

Improvement of flexural and cyclic performance of bridge deck slabs by utilizing steel fiber reinforced concrete (SFRC)

This paper aims at investigating how the utilization of steel fiber reinforced concrete (SFRC) improves the flexural and cyclic responses of reinforced concrete bridge deck slabs. Firstly, one plain concrete slab and two SFRC slabs reinforced by mill-cut steel fibers and corrugated steel fibers, respectively, were tested under cyclic loads. The load–deflection responses, cyclic deformation behaviors, strain and crack evolutions are discussed. Subsequently, a theoretical analysis method of SFRC slab is introduced and validated. Using this method, the effects of key strength parameters of SFRC, i.e. fL, fR1, fR4, on load–deflection responses and deck slab design indices (i.e. slab height, areas of steel rebars, slab span) are clarified through parametric analysis. Results demonstrate that using SFRC in deck slabs significantly enhances the cyclic deformation performance, decreases the residual strain in the slab section, and improves the crack behavior by reducing residual crack width and increasing cracking stiffness. An increase in fL and fR1 can enhance service capacity Ps and flexural stiffness ks, as well as improve design indices under the service requirement, whilst the influences of fR4 are minor. Increasing fR1 and fR4 can enhance ultimate capacity Pu and improve design indices under the ultimate requirement, whereas the effects of fL are rather limited. Since the use of mill-cut steel fibers produces higher fL and fR1 than corrugated steel fibers, the former has better advantages to enhance Ps and ks. These results may provide references for the application of SFRC in bridge deck slabs.

Reinforced concrete slabs strengthened with externally bonded carbon fibre-reinforced polymer strips under long-term environmental exposure and sustained loading. Part 1: Outdoor experiments

Carbon fibre-reinforced polymers (CFRPs) can be used to increase the load-bearing capacity of concrete bridge deck slabs and their lateral cantilevers. In this study, experiments were performed to explore the long-term performances of loaded RC slabs strengthened on the top surface using non-prestressed and prestressed externally bonded (EB) CFRP strips. A real bridge application was simulated by applying mastic asphalt on the top surface. The effects of four years of outdoor exposure to elevated temperatures and solar radiation were considered. The results show that specimens strengthened with non-prestressed EB CFRP strips exhibit satisfactory behaviours, but a substantial increase in strain is shown in the CFRP strips over time. A slab strengthened with prestressed EB CFRP strips anchored with a so-called gradient anchorage experiences premature failure, owing to elevated temperatures and sustained loads.

Numerical Deformation Analysis of Reinforced Lightweight Aggregate Concrete Flexural Members.

In the modern construction industry, lightweight aggregate concrete (LWAC) is often used to produce load-bearing structural members. LWAC can be up to 40% lighter by volume than normal strength concrete. However, the lack of adequate numerical models often limits the practical application of innovative building materials such as lightweight concrete in real projects. The present study conducted a comparative numerical deformation analysis of a full-scale bridge deck slab and girder. Using the physical model proposed by the authors and the finite element software ATENA, the deformations of full-scale lightweight and traditional reinforced concrete elements under the short-term effects of permanent and variable loads were compared. Depending on the safety and serviceability limit requirements, it was found that the amount of longitudinal reinforcement in lightweight reinforced concrete elements could be reduced compared with that in standard reinforced concrete elements with the same parameters. The results of the numerical analysis showed that the deformation analysis model proposed by the authors could serve as an alternative tool for the design of lightweight concrete flexural members with the selection of optimum geometric and reinforcement parameters limited by the stiffness condition.

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

The examination of applicability of the long basis optical stand sensors regarding the progression of deterioration of the RC bridge deck slabs

The examination of applicability of the long basis optical stand sensors regarding the progression of deterioration of the RC bridge deck slabs

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.

Comparative Evaluation of Crack Width for Reinforced Concrete Bridge Deck

Abstract: Cracking in reinforced concrete bridge decks is a massively concern in the India. Many concrete bridge decks, inobservant to the age of construction, have shown different levels and patterns of cracking. Not only does cracking of bridge decks weaken the bridge infrastructure, but also allows the inflow of corrosive agents into the reinforcement. In this study, the crack width evaluation of RC bridge deck of span of 5 m. and 9 m. is based on equations given by IRS Concrete Bridge Code 1997 for different cases like- the effect of depth variation, reinforcement diameter, clear cover, variation in live load moment, spacing of tension reinforcement and different no. of tension reinforcement bar to constant width for the same crosssection. This study concluded that crack width increases with increase in clear cover, variation in live load moment and spacing of tension reinforcement while it decreases with increase in reinforcement diameter, depth of the bridge deck and number of reinforced bars and percentage change evaluation of different parameter of 5m and 9m span bridge deck. Keyword: Crack Width, Cracking, Bridge Deck Slab, Crack Spacing.

Effect of Skew Angles on Longitudinal Girder and Deck Slab of Prestressed Concrete T Beam Girder Bridges

Abstract: The present paper shows the effects of varying skew angles on pre-stressed concrete (PSC) bridges using finite elemental method. Studies are carried out on PSC bridge decks to understand the influence of skew angle and loading on behaviour of bridges. The results of skewed bridges are compared with straight bridges for IRC Class AA Tracked loading. Also, a comparative analysis of the response of skewed PSC Slab Bridge decks with that of equivalent straight bridge decks is made. The variation of maximum longitudinal bending moment (BM), maximum transverse moment, maximum torsional moment, and maximum longitudinal stresses deflection at obtuse corner, acute corner with skew angles are studied for bridge deck. It is found that Live load longitudinal bending moments decreases with an increase in skew angle, whereas a maximum transverse moment and maximum torsional moment increases with an increase in skew angle. The benefit of pre-stressing is reflected in considerable decrease in the longitudinal bending moment, transverse moment and longitudinal stresses. The models are analysed with the help of software CSI-Bridge V 20 Version. Keywords: Skew angle effect, Longitudinal moment, Transverse moment, CSI- Bridge software, Deck slab, Finite element method.

Moving-wheel fatigue durability of cantilever bridge deck slab strengthened with high-modulus CFRP rods

Reinforced concrete (RC) slabs of highway bridge decks are gradually deteriorated due to the traffic vehicle wheel-loading. Fatigue is one of a number of possible causes for the deterioration. Cantilever RC slabs of the bridge are also damaged by fatigue loading. To increase the fatigue durability of the bridge deck slab, the near-surface mounted (NSM) technique is used with carbon fiber reinforced polymer (CFRP) rods embedded in the RC slab as an effective strengthening method. This study presents the fatigue characteristics of cantilever RC slabs strengthened with CFRP rods with a high-modulus of elasticity. A cantilever RC slab specimen with embedded CFRP rods with high moduli was constructed on a moving-wheel load testing machine and tested for approximately 11 months. The slab had a minimum thickness of 160 mm (as stipulated by the Japanese design code), and the minimum number of steel reinforcements was embedded to ensure (negative) flexural failure of the RC slab where CFRP rods were not used. During the test, the CFRP strengthened slab specimen was subjected to a negative bending moment from repeated moving-wheel loads. Very limited experimental data are available for the evaluation of the structural behavior of cantilever bridge decks subjected to wheel loads. Therefore, the moving-wheel fatigue experiment of the cantilever RC slab with NSM CFRP rods would be useful information for strengthening. The moving-wheel loading test confirmed the increase in fatigue durability of the CFRP strengthened slab as the slab specimen endured approximately 3.56 million equivalent-cycles at an initial load of 60 kN, which was 32% higher than the designed service load. The experimental investigation revealed that the ultimate failure of the cantilever slab was punching shear failure attributed to the rupture of the CFRP rods.

Evaluating in-service structural behaviour of an operational railway bridge using fibre optic sensing and structural model updating

Multi-girder prestressed concrete bridges are a very common structural form for bridges around the world. Their continued use is expected in the future given the advantages these structures have with respect to speed of construction, reduced maintenance and improved material efficiency. However, the in-service behaviour of these types of structures, such as their load distribution characteristics, support boundary conditions and the contribution of secondary elements, is still not well understood, and few studies have investigated these areas in depth. Gaining better insight into these aspects of bridge behaviour will enable more realistic structural assessment and thus facilitate more targeted maintenance and refurbishment of these bridges. This paper evaluates the in-service structural behaviour of an operational prestressed concrete railway bridge, which has been monitored using a dense network of fibre optic strain and temperature sensors since it was constructed in 2015. In particular, the normalised curvature profiles and the neutral axis positions across the composite solid slab bridge deck may be used to extract information about the bridge’s transverse load distribution behaviour, support boundary conditions and the stiffness contribution of secondary elements. Using this information, structural model validation and updating were performed with the goal of providing a more realistic assessment of structural behaviour and structural capacity. The proposed methodology and workflow in this study provide new insights into the real performance of multi-girder prestressed concrete bridges and thus can be used to improve their operation, maintenance, assessment and refurbishment.

Sustainability Levels in Comparison with Mechanical Properties and Durability of Pumice High-Performance Concrete

In the production of cement and concrete, mechanical and durable properties are essential, along with reasonable cost and sustainability. This study aimed to apply an evaluation procedure of the level of sustainability of mixtures of high-performance concretes (HPC) with various eco-friendly supplementary cementitious materials (SCM). The major supplementary cementitious materials (SCMs), namely, volcanic pumice pozzolan (VPP), Class C and F fly ash, ground granulated blast furnace slag of grade 120, silica fume, and metakaolin, were included. Twenty-seven concrete mixtures were analyzed using a previously presented comprehensive material sustainability indicator in a cost-effective variant. The results indicated that the rank of the concretes differed at 28, 56, and 91 days after concreting. In addition, the study showed no correlation of strength and diffusion parameters with sustainability indicators. Finally, this study will contribute to the optimal selection of mixtures of HPC with VPP in terms of sustainability, cost, and durability for future implementation in reinforced concrete bridge deck slabs and pavements. The values of sustainability indicators for pumice-based mixtures were compared with those for other SCMs, highlighting the sustainable performance of volcanic ash-based SCM.

RC 슬래브 교량 바닥판의 철근노출 및 부식에 대한 상태평가와 안전성 분석

본 논문은 국내 교량의 23.5 %를 차지하고 공용연수 30년 이상 된 교량의 55.2 %를 차지하는 RC 슬래브 교량에 대해서 바닥판 하부 표면손상에 의한 철근노출과 철근부식에 따른 상태평가 등급과 구조적 안전성을 분석하였다. 대상 RC 슬래브 교량은 실제 교량을 대상으로 설계도면을 참고하여 수치해석 모델을 구성하였다. 철근노출면적률과 부식률은 한국시설안전공단 정밀안전진단 세부지침의 상태평가 등급 기준을 참고하여 교량 바닥판 하부 인장철근 위치에서의 콘크리트 피복 탈락을 가정하여 총 35가지의 철근 부식 시나리오를 적용하였다. 각 시나리오별 해석 결과를 바탕으로 교량의 안전율과 내하율을 산정하여 안전성평가 및 철근노출면적률과 철근부식률에 대한 영향을 분석하였다. 안전율과 내하율은 철근노출면적률의 변화에는 영향이 거의 없었고, 철근부식률 증가에는 선형감소를 보였다. 선형추세선 분석을 통해 철근부식률이 4 %까지는 A등급, 10.77 %까지는 C등급, 16.74 %까지는 D등급, 그 이상일 때는 E등급으로 평가되었다. 노후화된 교량이 지속적으로 증가되고 있는 상황에서 육안조사에 의한 상태평가 결과와 철근부식에 따른 안전성평가 결과와의 비교 분석이 더욱 필요할 것으로 판단된다.

Quasi-static strength of bridge fingerplates under various design parameters

Fingerplate expansion devices are commonly used to account for movements and rotations of two bridge deck slabs. Under high traffic volumes, these devices experience premature damage that affects the structural integrity of the bridge superstructure. In this paper, a group of experimental tests and 3D elastic–plastic finite element models (FEMs) were conducted to study the structural behavior and modes of failure of this type of joints. The experimental results were also used to validate the FEMs, from which additional FEM models were employed to study the effects of various design parameters. The parametric study results showed that the finger thickness did not influence the response in the absence of stiffeners. On the other hand, the presence of stiffeners increased the finger joint stiffness while decreased the device ductility. Welding zones were the sites of crack initiation in most of the studied cases. The numerical results showed that the locations of the highest stress concentrations were in the weld between the fingerplate and the supporting beam top flange and in the weld between the stiffeners and the top flange.

Extended CSDT model for shear capacity assessments of bridge deck slabs

The shear strength evaluation of reinforced concrete bridge deck slabs by accurate models can indicate strength reserves and avoid costly operations necessary for the extension of their lifetime. This article introduces an approach that extends the Critical Shear Displacement Theory model (CSDT) for reaching higher levels of approximation of the shear strength for slabs subjected to concentrated loads close to the support. A database with 141 tests of wide reinforced concrete members under concentrated loads close to the support failing in one-way shear was built. The tests represented typical loads in bridge slabs and were assessed through a combination of CSDT with different models of effective shear width. In other analyses, the entire database with 214 test results of slabs failing by different mechanisms was evaluated and a general effective shear width model was proposed (GESW). The best results, which are a function of the effective shear width model used, reached a mean ratio between experimental and predicted shear capacities of 1.06 with a coefficient of variation of 14%, which is similar to that reported by some studies including linear and non-linear finite element analyses. Furthermore, this level of accuracy was insensitive to the shear slenderness and support conditions of the tests. The extended CSDT predicted the shear capacity of bridge deck slabs in preliminary analyses more precise than semi-empirical models provided in the current design codes, and the level of accuracy is comparable to methods using Linear Elastic Finite Element Analyses (LEFEA). Moreover, our proposed combination of the CSDT with a general effective shear width model (GESW) provides reasonable levels of accuracy for slabs under concentrated loads regardless of the failure mode of the tests. Therefore, the proposed approaches can be applied to bridge deck slabs, which are subjected to a variety of loading and support conditions.

Flexural response of Ultra-High-Performance Concrete (UHPC) hybrid bridge deck connections made with local materials

Although using of UHPC improves the mechanical properties of concrete, it is not widespread used, due to several factors; for instance, its high material cost, special curing requirements, and lack of widely accepted design guidelines. This study aims to find an appropriate Ultra-High-Performance Concrete (UHPC) mixture, using locally available materials. In addition, the flexural response of this locally made UHPC mixture in hybrid bridge deck connections has been studied. The effect of different parameters such as percentage of silica fume, fine aggregate type, glass powder content and steel fiber volume fraction were investigated. The compressive strength results showed that a 28 days-strength of 140.3 MPa (20.35 ksi) has been achieved by using basalt as fine aggregate and 20% silica fume by weight. To investigate the applicability of this locally produced UHPC in bridge joints closure, two full scale, 8 ft. clear span, hybrid bridge deck slabs with UHPC closure were constructed and tested under monotonic loading. The load–deflection behavior of the hybrid connection confirmed that the deflection increased linearly until the initiation of cracks, after that it was increased non-linearly up to the failure of the connection. UHPC experienced less strain than high strength concrete (HSC) under compression. The hybrid connection produced with local UHPC showed moment capacity increase by more than 80% compared to NSC. The Moreover, a moment–curvature analytical model of hybrid bridge deck connection was developed to predict ductility, curvature, and stress distributions in closure connections. The model was able to predict initial stiffness and ultimate flexural moments of UHPC composite connections very well.

Flexural and Shear Tests on Reinforced Concrete Bridge Deck Slab Segments with a Textile-Reinforced Concrete Strengthening Layer.

Many older bridges feature capacity deficiencies. This is mainly due to changes in code provisions which came along with stricter design rules and increasing traffic, leading to higher loads on the structure. To address capacity deficiencies of bridges, refined structural analyses with more detailed design approaches can be applied. If bridge assessment does not provide sufficient capacity, strengthening can be a pertinent solution to extend the bridge’s service lifetime. For numerous cases, applying an extra layer of textile-reinforced concrete (TRC) can be a convenient method to achieve the required resistance. Here, carbon fibre-reinforced polymer reinforcement together with a high-performance mortar was used within the scope of developing a strengthening layer for bridge deck slabs, called SMART-DECK. Due to the high tensile strength of the carbon and its resistance to corrosion, a thin layer with high strength and low additional dead load can be realised. While the strengthening effect of TRC for slabs under flexural loading has already been investigated several times, the presented test programme also covered increase in shear capacity, which is the other crucial failure mode to be considered in design. A total of 14 large-scale tests on TRC-strengthened slab segments were tested under static and cyclic loading. The experimental study revealed high increases in capacity for both bending and shear failure.

Nonlinear finite element analysis of full-scale concrete bridge deck slabs reinforced with FRP bars

Bridges with reinforced concrete deck slabs are more vulnerable to environmental-induced deterioration mainly due to corrosion. Carbon and glass fiber reinforced polymer (FRP) bars are getting attention as an alternative to steel bars to enhance the overall performance of the concrete bridge deck slabs and minimize corrosion-induced deteriorations. This study presents a 3D nonlinear finite element analysis (NLFEA) simulating the response of full-scale concrete bridge deck slabs reinforced with FRP bars. A control slab model was developed initially and properly calibrated and validated against published independent experimental results. A parametric study was then conducted through creating 27 NLFEA models with different parameters: concrete compressive strength, reinforcement type (glass FRP, carbon FRP, and steel), and bottom transverse reinforcement ratio. Monotonic single concentrated load was applied at the center of the concrete deck slab over a contact area of 600 mm × 250 mm, simulating the footprint of sustained truck wheel load. The CFRP and GFRP bars reinforcement of bridge deck slabs had superior effects on the ultimate load, elastic stiffness, post cracking stiffness, elastic energy absorption and post cracking energy and a little impact on ultimate deflection compared with steel reinforcement. Punching shear failure with a very similar cracking pattern was observed almost in all slabs and the bottom transverse reinforcement ratio is the main parameter affecting the tensile strains. For all slabs reinforced with GFRP and CFRP bars, the maximum measured strains in the bars at failure were less than 50% of their ultimate strain. Increasing concrete compressive strength will increase the ultimate load capacity and corresponding deflection of the slab.

Safety of Eurocode Model for Prediction of Shear Strength of Bridge Deck Slabs

Deck slabs of box girder bridges designed according to the theory of allowable stresses are mostly without shear reinforcement. In the case of new bridges, designed according to Eurocodes, significantly increases an application of shear reinforcement. This raises a question: are bridges built before implementation of the Eurocodes safe? The paper deals with safety analysis of the models for prediction of the shear capacity using results of more than 40 tests carried out on clamped slabs subjected to concentrated load. The analyses have shown that methods based on an effective shear width provide unsafe results for shear span to effective depth ratio larger than 3. A significant improvement of the model's safety has been attained by limiting the distance of critical section from the inner edge of the loaded area.

Effective methodology of sustainability assessment of concrete mixtures

Sustainability approach is a key conceptual principle to be considered in cement and concrete production all around the world. This study aims to enhance the methodology of a versatile effective sustainability assessment in a simple manner. The feasibility of proposed methodology is demonstrated on selected field application related to reinforced concrete bridge deck slabs where strength and durability are of prime interest. Various high-performance concrete (HPC) mixtures suitable for effective utilization in science and practice are selected as an example of the sustainability evaluation. The focus is paid to a complex sustainability assessment considering major important indicators: performance, durability, eco-costs and concrete mixtures costs and they are combined efficiently into one complex indicator applied at the early stage of design process. The enhancement in the form of such a general approach allows the consideration of these indicators and its normalization with the reference values is proposed. The results of experimental investigation on twenty-four various HPC mixtures are utilized to demonstrate the feasibility of proposed approach considering concrete’s compressive strength and its resistance against chloride-induced corrosion to serve as both performance and durability indicator. The results indicate the sustainability level of concrete mixtures and demonstrate the optimum possible choice of concrete mixtures with best performance/eco-costs/durability and economy trade off in the view of sustainability assessment.