Advances in Methodology for Fatigue Assessment of Composite Steel–Concrete Highway Bridges Based on the Vehicle–Bridge Dynamic Interaction and Pavement Deterioration Model

Abstract

Fatigue cracking is one of the most prominent causes of mechanical failure limiting the service life of existing steel and composite steel–concrete bridges and is among the central concerns of structural and bridge engineers. In this context, the current work presents some recent advancements in an existing methodology for fatigue analysis developed by the authors throughout the years. The methodology is specifically devoted to the fatigue assessment of composite steel–concrete bridges employing the local hot-spot S-N approach and a coupled vehicle–pavement–bridge system considering progressive pavement deterioration with stochastically generated roughness profiles. Two different methodologies were used to solve the dynamic equilibrium equations: the modal superposition method to solve the bridge dynamic equations and a direct integration method to solve the vehicle dynamic equations. From a computational point of view, the present approach is more efficient and detailed than previous versions, as it allows a significant reduction in the analysis time and the use of complex bridge and vehicle finite element models. In this regard, a case study of a highway composite steel–concrete bridge spanning 40 m was selected in order to demonstrate the usefulness of the presented improved methodology by carrying out a fatigue analysis. The results of this investigation (displacements and stresses) are presented, aiming to verify the factors that directly influence the structural response and, consequently, the service life of steel–concrete composite highway bridges.

Structural Assessment of Composite Highway Bridges Considering Vehicle‐bridge Dynamic Interaction

“…In this context, with the purpose of contemplate the pavement progressive deterioration, Paterson and Attoh-Okine [12] have developed a model considering the International Roughness Index (IRI) with the values at any time after starting the road surface service, which is calculated by Eqs. (3)(4):…”

“…In this scenario, although an assessment of the dynamic effects of vehicles on steel and composite highway bridges is extremely necessary, bridge design has been traditionally carried out through static or quasi-static analyses, considering equivalent loads based on design standards, with a dynamic amplification factor, which conservatively simulate the dynamics effects of vehicles traffic [2], [3]. Therefore, in these recent years, many studies have been developed with the aim of improving the provisions of design standards.…”

“…With regard to the phenomenon of fatigue, according to Fisher et al [4], the structural details with welded joints are considered as the most fragile points of steel and composite highway bridge designs, and almost 90% of all fatigue cracking cases are the result of out-ofplane distortion or other unforeseen secondary stresses in fatigue-sensitive details. Still in relation to fatigue failure in welded joints, this process is subdivided into four stages: cyclic hardening, crack initiation, crack propagation and final failure [3]. Although welded joints are evaluated in current design codes using primarily the Nominal Stress Method (NSM), in this paper, for a better accurate stress definition, the Hot-spot Stress Method (HSM) was used.…”