Development of sustainable concrete bridge deck slab systems using corrosion-resistant GRFP bars

This research investigates the use of glass fiber reinforced polymer (GFRP) bars to reinforce the bridge deck slabs as well as jointed precast bridge deck slab in prefabricated bulb-tee pre-tensioned bridge girders. The experimental program included two phases. In phase (I), six precast slab joint details between flanges of precast bulb-tee girders were developed incorporating GFRP bars with straight ends, L-shaped ends and headed ends, embedded in a closure strip filled with non-shrink cement grout or ultra-high-performance concrete (UHPC). A total of 11 actual-size specimens representing the one-way slab system with the proposed joint details, in addition to 5 cast-in-place control specimens, were built and tested to failure to examine the structural adequacy of the proposed joint details. Based on the results from Phase (I), the best joint was selected for further tests in Phase (II) to examine its fatigue life and ultimate load carrying capacity under vehicular wheel loading. A total of 8 actual-size, GFRP-reinforced, 3500 X 2500 X 200 mm concrete deck slabs were designed for this purpose according to CHBDC specifications. Ultimate strength, fatigue behavior and fatigue life of the GFRP-reinforced deck slabs were investigated using different schemes of fatigue loading, namely: accelerated variable amplitude fatigue loading and constant amplitude fatigue loading. Overall, the experimental results indicated that GFRP-reinforced deck slabs showed high fatigue performance. A new prediction model for fatigue life of the GRFP-reinforced deck slabs was developed. The failure mode of the tested composite slabs was punching shear. Correlation between the experimental findings and the prediction models for punching shear resistance available in the literature showed that the prediction models by CSA S806-12 (2012) and El-Gamal et al. (2005) can accurately predict the punching shear capacity of the cast-in-place and precast jointed bridge deck slabs reinforced with GFRP bars. In addition, the average observed mid-depth punching shear perimeter for the cast-in-place deck slabs and the precast jointed deck slabs were measured to be 1.25 d and 1.33d away from the sides of the loaded area, respectively, which are more than twice the corresponding distance specified in ACI 440.1R-06 and CSA S806-12 for calculating the critical punching shear perimeter.

Development of sustainable concrete bridge deck slab systems using corrosion-resistant GRFP bars

This research investigates the use of glass fiber reinforced polymer (GFRP) bars to reinforce the bridge deck slabs as well as jointed precast bridge deck slab in prefabricated bulb-tee pre-tensioned bridge girders. The experimental program included two phases. In phase (I), six precast slab joint details between flanges of precast bulb-tee girders were developed incorporating GFRP bars with straight ends, L-shaped ends and headed ends, embedded in a closure strip filled with non-shrink cement grout or ultra-high-performance concrete (UHPC). A total of 11 actual-size specimens representing the one-way slab system with the proposed joint details, in addition to 5 cast-in-place control specimens, were built and tested to failure to examine the structural adequacy of the proposed joint details. Based on the results from Phase (I), the best joint was selected for further tests in Phase (II) to examine its fatigue life and ultimate load carrying capacity under vehicular wheel loading. A total of 8 actual-size, GFRP-reinforced, 3500 X 2500 X 200 mm concrete deck slabs were designed for this purpose according to CHBDC specifications. Ultimate strength, fatigue behavior and fatigue life of the GFRP-reinforced deck slabs were investigated using different schemes of fatigue loading, namely: accelerated variable amplitude fatigue loading and constant amplitude fatigue loading. Overall, the experimental results indicated that GFRP-reinforced deck slabs showed high fatigue performance. A new prediction model for fatigue life of the GRFP-reinforced deck slabs was developed. The failure mode of the tested composite slabs was punching shear. Correlation between the experimental findings and the prediction models for punching shear resistance available in the literature showed that the prediction models by CSA S806-12 (2012) and El-Gamal et al. (2005) can accurately predict the punching shear capacity of the cast-in-place and precast jointed bridge deck slabs reinforced with GFRP bars. In addition, the average observed mid-depth punching shear perimeter for the cast-in-place deck slabs and the precast jointed deck slabs were measured to be 1.25 d and 1.33d away from the sides of the loaded area, respectively, which are more than twice the corresponding distance specified in ACI 440.1R-06 and CSA S806-12 for calculating the critical punching shear perimeter.

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.

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.

Verstärkung für Fahrbahnplatten von Massivbrücken aus Textilbeton: Versuche zur Realisierung eines Demonstrators/Strengthening of Solid Bridge Deck Slabs with Textile Reinforced Concrete: Demonstrator Tests

Zusammenfassung Verkehrssteigerungen erhöhen die Anforderungen an den Brückenbestand. In einem vom Bundesministerium für Bildung und Forschung (BMBF) geförderten Verbundprojekt wurde eine dünne Ergänzungsschicht aus Textilbeton – Smart-Deck – für Brückenfahrbahnplatten mit drei Eigenschaften entwickelt: Feuchtemonitoring, präventiver kathodischen Korrosionsschutz und Erhöhung der Tragfähigkeit. Am Institut für Massivbau der RWTH Aachen (IMB) wurde die Verstärkungswirkung in Hinblick auf die Biege- und Querkrafttragfähigkeit untersucht. Nach einigen Laborversuchen zur Findung geeigneter Materialkombinationen und gezielten Untersuchung der oben genannten Funktionen der carbonbewehrten Zusatzschicht wurde ein erster Demonstrator realisiert, an dem die baustellengerechte Herstellung von Smart-Deck und weiterhin die nach realitätsnaher Herstellung erreichbaren Funktionen überprüft werden konnten. Im nachfolgenden Beitrag werden die experimentellen Untersuchungen vorgestellt, über die der Beitrag von Smart-Deck zur Tragfähigkeit der Demonstratorplatte ermittelt werden konnte. Dazu wurden Streifen mit unterschiedlichem Biegezugbewehrungsgrad entnommen und am IMB mit variierenden Laststellungen getestet.

Shear resistance of clamped deck slabs assessed using design equations and FEM analysis

Reinforced concrete (RC) slabs without shear reinforcement are commonly used in the existing bridge structures. An ability of RC slabs to distribute the concentrated loads due to the wheel pressure in transverse direction is an important property for their verification. The aim of this paper is to investigate the effect of redistribution of shear forces and bending moments on the load carrying capacity of RC slabs subjected to concentrated loads. Two methods of the assessment are used: simplified analytical formulations and linear finite element analysis (LFEA). The obtained results are consequently compared with the test results taken from three experimental campaigns. The analyses show big differences among the results obtained from the simplified analytical methods that are based on the design equations introduced in the relevant standards. Improved methods, such as LFEA combined with analytical post-processing method, reflect the structural behaviour in a better way and provide more accurate load-bearing capacity prediction of the bridge deck slabs.