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Mean effective width (B eff ) from all SP1 cyclic tests in each group (bar chart) and overall average effective width from all groups (dashed lines) at section B.
Source publication
The objective of this paper is to revise the effective slab width of integral bent cap beams in reinforced concrete box-girder bridges. Currently, a conservative code-based value of 12 times the slab width plus the cap beam width is used to define the beam's top and bottom flange widths to account for the box-girder slab contribution as part of the...
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Citations
... Later studies by Moustafa and Mosalam (2016) explained experimentally a procedure for determining the effective width based on the equivalent strain block concept. The strain distribution was obtained by distributing many strain gauges around the load. ...
For any slab deck bridge, the ultimate loading strength is obtained based on the distribution of that loading to a slab effective width that recommended in the adopted specifications. In this study, a simplified procedure with a design equation is presented. This procedure depends on the determination of the moments developed in a slab deck bridge and thus the slab effective width that loading is distributed to. The study employs the Iraqi military tracked load. The procedure applies to right, simply supported slab deck bridges with and without edge stiffening beams based on the aspect ratio that represents the ratio of the slab width to length. A 3D finite element analysis by a well-known programme ABAQUS was conducted to analyse the whole bridges and to give the values of moments that will be used in the derivation of an equation to calculating the slab effective width. Furthermore, a comparison between the effective width of this study and the AASHTO and LRFD specifications was conducted. It is found that this method gives some conservative results in comparison with AASHTO and LRFD standards because other standards have some limitations, besides not to take in consideration all the parameters required.
... The bent cap and slab reinforcing bars in both compression and tension sides were extensively instrumented with strain gages to determine the strain distribution. A simple procedure was devised to determine the effective slab width based on the concept of an equivalent strain block [9,16]. The strain distribution was experimentally obtained and spatially extended at the two tails to determine the intercepts at zero strains. ...
... Fig. 10b shows the strain distribution along the cross-section at one of the critical sections in the bent cap bottom reinforcement and adjacent soffit slab transverse reinforcement. The strain results were used to estimate the equivalent effective slab width at two critical bent cap sections (Figs. 9, 10) using the same procedure previously used in the experimental program [16]. The summary of effective width results are discussed in a following section. ...
The objective of this paper is to revise the design methodology of integral bent cap beams in reinforced concrete box-girder bridges. In particular, this paper provides new provisions for estimating integral bent caps effective slab width and moment capacity and study the design implications of these provisions. Currently, a conservative code-based value of 12 times the slab thickness plus beam width is used to define bent caps top and bottom flange widths to account for the box-girder slab contribution as part of the bent cap analysis and seismic capacity design. The paper presents an overview of a large-scale experimental study and full-scale bridge finite element study that investigated integral bent cap effective slab widths. A strain-based approach for estimating the effective width suggests that 18 times the slab thickness is a more accurate representation of the box-girder slab contribution to the bent cap stiffness and capacity. It is shown that using the revised effective width while considering the slab reinforcement within this effective width is more accurate than current code provisions to estimate the moment capacity of bent caps and perform capacity checks. A design case study is presented to demonstrate the implications of using the proposed revised design methodology on the seismic capacity checks for a typical California box-girder prototype bridge under different design scenarios. It is concluded that the integral bent cap revised design methodology can lead to a more economical reinforcement design in case of high seismic demands in light of AASHTO seismic design provisions.
