Papers by Author: Max A.N. Hendriks

Abstract: Several reliability methods available in literature combined with various modelling approaches are compared in this current work in the context of two experimental reinforced concrete (RC) beams. One beam failed in bending while the other beam failed in shear due to diagonal tension. The structural behaviour is described by analytical models and nonlinear finite element models. The changes in predicted reliability of these structures with increasing loads are evaluated by different reliability methods and the results are compared

Abstract: The last decades the concrete-ice abrasion process has been well known as a concrete surface degradation mechanism due to ice sliding. The topic is especially relevant for concrete gravity based structures in the Arctic offshore. The article presents a numerical model in which the onset of wear in the concrete-ice abrasion process is simulated. The simulations are performed on meso-scale, which means that concrete is modelled as a three-phase material in which paste, aggregates and the interface transition zone are distinguished. Lattice modelling is adopted for the numerical modeling. Hertzian contact theory which predicts excessive tensile stresses on the concrete surface due to sliding of ice asperities is used as an analytical basis for the numerical model. It was concluded that such model is able to capture both surface and subsurface cracking in the concrete.

Abstract: The paper presents a model that splits the material cross section into a number of parallel fractions each of them having a different elastic-perfectly brittle characteristic. The idea is that the summation of all parallel fractions provides an approximation of the overall continuum softening curve. Softening is interpreted as a gradual reduction of the cross-sectional area, which it actually is from a physical point of view. Disorder and heterogeneity are introduced by assigning the fractions i different values of Young’s modulus E_i , strength f_i and area A_i such that the overall fracture energy is consumed properly. The model blends well with a scaled sequentially linear solution procedure at global level tracing structural failure via successive snapping/cracking of critical fractions. Examples are included for tension, compression, combined tension-shear and combined tension-compression. The tension-shear case shows the ability of the model to capture a gradually shifting crack orientation. Preliminary structural examples are included in this paper and further results will be presented at the conference. These relate to push-over analysis of Groningen masonry building stock subjected to man-induced earthquakes from gas depletion, a currently serious problem in The Netherlands. The results show an increased robustness and stability of the post-peak response as compared to conventional incremental-iterative procedures.

Abstract: The architectural heritage is subjected to various risk factors like the lack of maintenance, the material decay and the external solicitations. Nowadays, due to the ever-increasing demand for urban space, a relevant cause of structural damage that the historical buildings experience is the ground settlement due to excavation works. In the city of Amsterdam, for example, the construction of the new North-South metro line will involve an area characterized by the presence of many ancient masonry buildings. A fundamental phase of the design of this kind of projects is the assessment of the risk of subsidence which can affect the existing structures. The actual method to perform this assessment provides for a preliminary screening of the buildings located in the area surrounding the excavation, in order to evaluate which structures are at risk of settlement induced damage. It is based on the simplification of the building as a linear elastic beam and the assumption of the absence of interaction between the soil and the structure. An improved classification system should take into account the main parameters which influence the structural response, like the nonlinear behaviour of the building and the role played by the foundation in the soil-structure interaction. In this paper, the effect on the damage mechanism of the excavation advance and the location of the tunnel with respect to the building is evaluated. Numerical analyses are performed in order to understand the effect of different settlement profiles of the ground. A coupled model of the structure and the soil is evaluated, taking into account a damage model for the masonry building and the nonlinear behaviour of the soil-structure interaction. This paper demonstrates the importance of 3D modelling; neglecting the tunnel advance can lead to an underestimation of the damage.