The aim of this paper is to introduce and characterize, both experimentally and numerically, three classes of non-traditional 3D infill patterns at three scales as an alternative to classical 2D infill patterns in the context of additive manufacturing and structural applications. The investigated 3D infill patterns are biologically inspired and include Gyroid, Schwarz D and Schwarz P. Their selection was based on their beneficial mechanical properties, such as double curvature. They are not only known from nature but also emerge from numerical topology optimization. A classical 2D hexagonal pattern has been used as a reference. The mechanical performance of 14 cylindrical specimens in compression is quantitatively related to stiffness, peak load and weight. Digital image correlation provides accurate full-field deformation measurements and insights into periodic features of the surface strain field. The associated variability, which is inherent to the production and testing process, has been evaluated for 3 identical Gyroid specimens. The nonlinear material model for the preliminary FEM analysis is based on tensile test specimens with 3 different slicing strategies. The 3D infill patterns are generally useful when the extrusion orientation cannot be aligned with the build orientation and the principal stress field, i.e., in case of generative design, such as the presented branching structure, or any complex shape and boundary condition.

The corrosion of reinforcement is one of the major causes of deterioration of reinforced concrete (RC) structures, considerably affecting their durability and reliability. The rate of reinforcement corrosion is governed by, among other factors, the presence of chlorides on the surface of the steel. The assessment of such deteriorating effects necessitates the development of relevant models and the utilization of advanced simulation techniques to enable the probabilistic analysis of concrete structures. In this article an approach for the assessment of the durability and reliability of RC structures under attack from chlorides is introduced. The field of chloride concentration at different locations in the structure (represented in 2D space by chosen longitudinal or cross sections) is modeled as a function of time by a cellular automata (CA) technique. The results of this simulation are then utilized for the assessment of a steel corrosion prognosis using a probabilistic 1D model at chosen points, although the rate of corrosion is based on experimental results. The concentrations of chlorides and pH levels are reflected in this way. The described approach is applied to an illustrative example showing the feasibility of capturing the effect of chloride concentration on the steel corrosion rate and consequently on the assessment of the service life and/or reliability of the structure.

Life‐cycle civil engineering addresses, among other things, the growing number of deteriorating bridges and the associated economic challenges. As a consequence, government bodies, infrastructure and bridge owners as well as industry request objective and rational performance indicators for classification and intervention planning in structural engineering. This paper focuses on a methodology for analysing the damage‐based robustness margins of bridge systems under traffic loading. In particular, a series of emergent deterioration‐based damage scenarios are compared with the actual or virgin state in terms of loadbearing capacity and serviceability. Non‐linear finite element analysis based on a detailed 3D model has a high potential for capturing the available bridge capacity for different degradation phenomena and levels, serving as an input for further reliability‐based performance indicators. Notwithstanding, costs associated with fully probabilistic assessment measures are still prohibitive despite technological advances and new methods of reducing the sample size in Monte Carlo computations. In addition, considering the large uncertainties and imprecision involved, it is imperative that probabilistic schemes are preferred over deterministic assessments. The objective of this article is to present strategies for robustness‐based performance assessment using non‐linear modelling and to discuss relevant reliability‐based quantities and performance indicators in relation to structural damage using the example of specific degradation events in an existing prestressed box girder bridge. Furthermore, some strategies are developed on the basis of the new approach for general complex engineering structures.

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