A multi-level structural assessment strategy for reinforced concrete bridge deck slabs

Abstract

This paper proposes a multi-level assessment strategy for reinforced concrete bridge deck slabs. The strategy is based on the principle of successively improved evaluation in structural assessment. It provides a structured approach to the use of simplified as well as advanced non-linear analysis methods. Such advanced methods have proven to possess great possibilities of achieving better understanding of the structural response and of revealing higher load-carrying capacity of existing structures. The proposed methods were used for the analysis of previously tested two-way slabs subjected to bending failure and a cantilever slab subjected to a shear type of failure, in both cases loaded with concentrated loads. As expected, the results show that more advanced methods yield an improved understanding of the structural response and are capable of demonstrating higher, yet conservative, predictions of the load-carrying capacity. Nevertheless, the proposed strategy clearly provides the engineering community a framework for using successively improved structural analysis methods for enhanced assessment in a straight forward manner.

Internal force distribution in RC slabs subjected to punching shear

“…At level III analysis according to Plos et al [16], nonlinear shell finite elements coupled with fully bonded reinforcement are used, with the capability of reflecting the bending behaviour of RC slabs directly in the FEA. Due to the symmetry of geometry and loading conditions, only a quarter of the slab was modelled (as an example, …”

“…Compared to 2D element models, a 3D element model offers a higher flexibility and accuracy in the modelling of out-of-plane behaviour of RC structures and generally results in more realistic results [16][17][18][19]. According to Shu et al [20][21][22], NLFEA using continuum finite elements (sometimes also referred to as solid finite elements) [16] is capable of not only predicting load carrying capacity, but also reflecting the structural behaviour of RC slabs, both in bending and shear aspects.…”

“…According to Plos et al [16], the modelling method at level III (shell element models) and level IV (continuum element models) are suitable. To obtain punching resistance at level III, the Critical Shear Crack Theory (CSCT) [23] can be used in combination with NLFEA.…”

“…According to Shu et al [20][21][22], NLFEA using continuum finite elements (sometimes also referred to as solid finite elements) [16] is capable of not only predicting load carrying capacity, but also reflecting the structural behaviour of RC slabs, both in bending and shear aspects. The difference between FE analyses at different levels has been discussed in a ''Multi-level Assessment Strategy for RC slabs" by Plos et al [16]. Case studies have shown that nonlinear FE methods with continuum elements normally yield an improved understanding of the structural response.…”

“…Meanwhile, Belletti et al [11][12][13] presented a nonlinear finite element (NLFE) approach which adopts multi-layered shell modelling of RC slabs and postprocessing of NLFE analyses (NLFEA) using the Critical Shear Crack Theory (CSCT) [15] to evaluate the punching shear resistance. In Belletti et al [11,12] NLFEA were carried out with the FE code ABA-QUS and the UMAT for user subroutine in which the crack model denoted as Physical Approach for Reinforced Concrete for Cyclic Loading (PARC_CL) was implemented [14][15][16].…”