Musolas, A.; Egozcue, J. J.; Crusells, M. Stochastic environmental research and risk assessment Vol. 30, num. 8, p. 2287-2301 DOI: 10.1007/s00477-015-1179-1 Data de publicació: 2016-12 Article en revista
Environmental risk management consists of making decisions on human activities or construction designs that are affected by the environment and/or have consequences or impacts on it. In these cases, decisions are made such that risk is minimized. In this regard, the forthcoming paper develops a close form that relates risk with cost, hazard, and vulnerability; and then focuses on vulnerability. The vulnerability of a system under an external action can be described by the conditional probability of the degrees of damage after an event. This vulnerability model can be obtained by a simplicial regression of those outputs, as a response variable, on explanatory variables. After a theoretical explanation, the authors present the case study of a nuclear power plant containment building. Once a given overpressure is registered inside the containment building, three possible outputs are to be considered: serviceability, breakdown, and collapse. The study consists of three steps: (a) modelling the containment building using the finite element method; (b) given an overpressure, simulating uncertain parameters related to material constitutive equations in order to obtain the corresponding proportions; (c) performing a simplicial regression to obtain a meaningful vulnerability model. The simulation provides normalized-to-unity outputs under the overpressure conditions. The obtained vulnerability model is in definite correspondence with previous results in nuclear power plant safety analysis reports.
The following paper deals with active control implementation in cable-stayed bridges. Recent developments in structural active control of cable-stayed bridges are focused on the adaptability to dynamic effects produced by earthquakes or extreme winds (El Ouni et al., 2012; Pakos and Wojcicki, 2014; Domaneschi et al., 2015a,b). Nevertheless, no attention has been paid to the static or quasi-static case. As stated by Housner et al. (1996), Song et al. (2006) or Gilewski and Al Sabouni-Zawadzka (2015), active control could also be useful to diminish fatigue in the day-to-day performance of this type of bridges by decreasing stresses adaptively. Indeed, the following paper shows that excitation periods produced by traffic loads and natural periods of vibration of this type of bridges are sufficiently distant one another so as to conclude that a quasi-static analysis can be performed. Filling this gap, the following paper proposes a structural analysis procedure to include active control systems in the design process of cable stayed bridges, as well as suggestions which ought to be considered in order to include these cases into codes. The results of the paper, studying both non-cumulative and cumulative load cases, show a reduction in unbalanced bending moment referred to the Neutral Moment State of around 25%, depending on the load case. As a result, active control systems compensating quasi-static loading patterns can certainly help engineers optimise the design of these emblematic structures.