STR-840: Investigation of Live Load Moment and Shear for the Design of Bridge Deck Slab Cantilevers with Unstiffened Edge or Built with TL-5 Barrier Wall (original) (raw)
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10th International Conference on Short and Medium Span Bridges, 2018
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This paper presents the results of six tests on R/C bridge cantilever slabs without shear reinforcement subjected to concentrated loading. The specimens represent actual deck slabs of box-girder bridges scaled 3/4. They were 10 m long with a clear cantilever equal to 2.78 m and with variable thickness (190 mm at the tip of the cantilever and 380 mm at the clamped edge). Reinforcement ratios for the specimens were equal to 0.78% and 0.60%. All tests failed in a brittle manner by development of a shear failure surface around the concentrated loads. The experimental results are investigated on the basis of linear elastic shear fields for the various tests. Taking advantage of the experimental and numerical results, practical recommendations for estimating the shear strength of R/C bridge cantilever slabs are proposed.
Proceedings of the International Conference on Civil, Structural and Transportation Engineering, 2024
This sensitivity study investigates the effect of intermittent construction joints on the moments, shear, and tensile forces on the barrier wall and deck slab overhang in slab-on-girder bridges due to transverse vehicle impact loads. This study used the threedimensional finite-element modeling of a 30 m long, TL-5, single-slope concrete barrier mounted over a 1 m length deck overhang. Spacing between intermittent expansion joints was taken at 3, 4, 5, and 6 m compared to the continuous barrier wall that equals the overhang length in the direction of traffic. The results from this research are pivotal in formulating robust empirical design equations in the future, marking a significant advancement in engineering practices for reliable bridge design. Results show that intermittent expansion joints, with spacings from 3 to 6 meters, cause an increase in the transverse moment at the inner side of the barrier wall for interior loads. However, the presence of these joints does not significantly alter the shear force at the barrier base or the tensile force at the inner side of the barrier wall, indicating that the primary impact of expansion joints is on the moment rather than shear or tensile forces. At the barrier end location, the presence of intermittent expansion joints over 3 m to 6 m spacings has an insignificant effect on the transverse moment and tensile force in the deck overhang at the inner side of the barrier wall (except for the 3 m spacing) and the shear force at the barrier base at the barrier end due to transverse vehicle impact load.
Wheel Load Distribution in Straight and Skewed Concrete Slab Bridges Stiffened with Railings
International Journal of GEOMATE, 2020
This paper presents the parametric investigation of the influence of railings on the wheel load distribution in simply-supported, one-span, three-and four-lane straight and skewed reinforced concrete slab bridges using the finite element method. A total of 96 bridge cases were modeled using finite-element analysis (FEA) and bridge parameters such as span length, slab width, and skew angle are varied within practical ranges. Typical railings built integrally with the bridge were placed on both edges of the deck slabs. AASHTO HS20 truck loadings were positioned transversely and longitudinally to produce maximum longitudinal live load bending moments in the slabs. The FEA wheel load distribution and bending moments were compared with reference straight bridges without railings as well as to the AASHTO Standard Specifications for Highway Bridges and the AASHTO LRFD Bridge Design Specifications. AASHTO overestimates FEA moments for almost all bridge cases and this overestimation increases with the increase in the skew angle, and it is more significant in the presence of two railings. Also, it was found that the reduction in slab moment due to skewness and railings is cumulative. The presence of railings can be considered to be a possible method for strengthening and rehabilitating straight and skewed concrete slab bridges.
International Journal of GEOMATE, 2017
The American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (AASHTO LRFD) do not account for the presence of railings as integral parts of highway bridges. This paper presents the parametric investigation of the influence of railings stiffness on the wheel load distribution in simply-supported, one-span, one-and two-lane reinforced concrete slab bridges using the finite-element analysis (FEA). A total of 80 bridge cases are modeled and bridge parameters such as span lengths and slab widths were varied within practical ranges. Various railings built integrally with the bridge deck are placed on both edges of the concrete slabs. The FEA wheel load distribution and bending moments are compared with reference bridge slabs without railings as well as to the AASHTO design procedures. According to the FEA results, the presence of railings reduces the longitudinal bending moment in slabs by 25% to 60% depending on the stiffness of the railings. The results of this investigation will assist structural and bridge engineers in better designing or evaluating concrete slab bridges in the presence of railings. This can also be considered to be a possible alternative for strengthening existing concrete slab bridges.
Influence of Railing Stiffness on Wheel Load Distribution in Two-Span Concrete Slab Bridges
Proceedings of International Structural Engineering and Construction, 2019
The American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications or LRFD do not account for the presence of railings in the analysis and design of concrete slab bridges. This paper presents a parametric investigation of the influence of railing stiffness on the wheel load distribution in simply-supported, two-equal-span, and one- and two-lane reinforced concrete slab bridges using the finite-element analysis (FEA). A total of 160 bridge cases were modeled and bridge parameters such as span lengths and slab widths were varied within practical ranges. Various railing stiffness were investigated by assuming railings built integrally with the bridge deck and placed on both edges of the bridge. The FEA wheel load distribution and longitudinal bending moments were compared with reference bridge slabs without railings as well as to the AASHTO design procedures. Accordingly, the presence of railings reduced the FEA negative moments by a range of 54% to...
Parapet Stiffness Effect on Load Carrying Capacity of Multi-Lane Concrete Slab Bridges
Proceedings of International Structural Engineering and Construction, 2020
Bridge specifications do not consider the effect of parapet stiffness in the analysis and design of reinforced concrete slab bridges. This paper performs a parametric investigation using finite element analysis (FEA) to study the effects of parapet stiffness on live load-carrying capacity of two-span, three-and four-lane concrete slab bridges. This study analyzed 96 highway bridge cases with varied parameters such as span-length, bridge width, and parapet stiffness within practical ranges. Reinforced concrete parapets or railings, built integrally with the bridge deck, were placed on one and/or both sides of bridge deck. The longitudinal bending moments calculated using the FEA results were compared with reference bridge cases without parapets, as well as AASHTO Standard and LRFD specifications. The FEA results presented in this paper showed that the presence of concrete parapets reduces the negative bending moments by 15% to 60% and the positive bending moments by 10% to 45%. The r...
Dynamic Behavior of Deck Slabs of Concrete Road Bridges
This paper treats the dynamic effect of traffic actions on the deck slabs of concrete road bridges using the finite-element method. All the important parameters that influence bridge-vehicle interaction are studied with a systematic approach. An advanced numerical model is described and the results of a parametric study are presented. The results suggest that vehicle speed is less important than vehicle mass and that road roughness is the most important parameter affecting the dynamic behavior of deck slabs. The type of bridge cross section was not found to have a significant influence on deck slab behavior. The dynamic amplification factor varied between 1.0 and 1.55 for the bridges and vehicles studied. These results should be validated by further work.
Recommendations for the Shear Assessment of Reinforced Concrete Slab Bridges from Experiments
Structural Engineering International, 2013
Upon assessment of existing reinforced concrete short-span solid slab bridges according to the recently implemented Eurocodes that include more conservative shear capacity provisions and heavier axle loads, a number of these structures were found to be shear-critical. The results from recent experimental research on the shear capacity of slabs indicate that slabs benefit from transverse load distribution. Recommendations for the assessment of solid slab bridges in shear are developed on the basis of these experiments. A load spreading method for the concentrated loads is proposed and the applicability of superposition of loading is studied. The resulting most unfavourable position for the design trucks is provided and implemented in the so-called Dutch "Quick Scan" method (QS-EC2). Cases of existing bridges are studied with the previously used QS-VBC as well as with the QS-EC2 that includes the recommendations. As a result of the assumed transverse load distribution, the shear stress to be considered at the support based on the recommendations becomes smaller.