Finite element study of effective width in steel-concrete composite beams under long-term service loads

Abstract

In this work, a finite element-based approach is presented to study the effective width variation in non-pre-stressed steel-concrete beams under the serviceability stage, including time dependent effects such as concrete creep, shrinkage and cracking. For this purpose, the viscoelasticity theory in conjunction with a nonlinear cracking monitoring algorithm is used to trace the nonlinear viscoelastic response of the structure along time. The present numerical model is fully three-dimensional and permits the inclusion of partial interaction at the slab-beam interface. A comprehensive study is carried out on the long-term response of a composite girder bridge previously studied by other researches. Then, previous results are revised and extended herein. Potential shortcomings of some standard codes related to the effective width evaluation are also investigated. It is demonstrated that the slab effective width varies sharply along the beam axis in the short-term, while it approaches to the actual slab width in the long-term. For the studied example, the common assumption of using only the middle layer of the reinforced concrete (RC) slab for the effective width calculation is revised with a through-thickness integration procedure. The influence of some creep and shrinkage models as well as the ultimate tensile concrete strain on the effective width response is also assessed. Finally, a simple formula is proposed to evaluate the short-term slab effective width for the studied example.

Numerical assessment of effective width in steel-concrete composite box girder bridges

“…These elements were pre-dimensioned according to the recommendations of AASHTO (2017). Furthermore, research has shown that the main parameters that influence the effective width are the slab height, span length, load type and application, the distance between beams and webs in the cross section and the steel-concrete interaction degree (Castro et al, 2007;Dezi et al, 2006;Gara et al, 2011;Hu et al, 2009;Reginato et al, 2018;Silva and Dias, 2018;Yuan et al, 2016;Zhu et al, 2015). Therefore, the parametric analysis variables were:…”

“…For the effective width study, the normal stresses in the slab were analyzed at the beginning of the concrete slab plastic behavior because the effective width cannot be measured when such an element reaches the plastic behavior. In this situation there is a uniform stress distribution and it would not be possible to analyze the shear lag effect (Amadio and Fragiacomo, 2002; Reginato et al, 2018).…”

“…The shear lag effect has been investigated by several authors who developed equations for determining the effective width of slabs in steel-concrete composite beams (Abbu et al, 2014; Amadio and Fragiacomo, 2002; Castro et al, 2007; Gara et al, 2011b; Lasheen et al, 2018; Reginato et al, 2018; Silva and Dias, 2018; Yuan et al, 2016; Zhu et al, 2015). It is worth mentioning the work of Abbu, Ekmekyapar and Ozakça (2014) that addressed steel-concrete composite bridges specifically in the box section configuration; and the research by Yuan et al (2016) and Zhu et al (2015), who investigated steel-concrete composite bridges and proposed expressions to determine the effective width.…”

Numerical Investigation of Distribution Laws of Shear Force in Box Girder Webs

“…Box girder is an important type of bridge structure. For box girder, many scholars have conducted research on shear lag, effective width [1][2][3][4][5], and live load distribution factors [6][7][8].…”

Some Aspects of Numerical Modeling of Steel-Concrete Composite Beams with Prestressed Tendons

“…Internal unbonded tendons may slip in relation to the surrounded concrete along its entire length, whereas external tendons only slip at deviator devices located along the longitudinal direction of the steel beam. The model is based on the enhacement of a previous model called VIMIS, developed by the authors, and which have served as FE tool for other numerical studies , Dias et al 2015, and Reginato et al 2018. The strategy for including internal and external prestressing and some aspects of the numerical modeling of composite beams are then commented in the following sections.…”