A methodology to determine optimal observation locations and its number is proposed based on Value of Information (VoI) and probabilistic spatial interpolation method known as Kriging. The risk of decision error is reduced in a decision making problem under uncertainty when new observation information is given. In the proposed method, VoI is defined as the expected reduction of decision error risk. Observation location is determined such that absolute value of VoI is maximized, whereas the number of observation is determined by minimizing the total cost, which is the sum of observation cost and VoI. In the issue that liquefaction countermeasure region along an existing river embankment is determined, locations and the number of additional boring are studied with the proposed method.
This paper presents a phenomenological material model for rubber-like solids and its numerical implementation. The model consists of a hyperelastic damage model in parallel with visco-elasto-plastic models, which include strain-dependency of the hysteretic loops. The underlying key feature of the model is an expression of free-energy of the visco-elasto-plastic model, in which the elastic strain energy is multiplied by a function of strain called hardening ratio, in order to reproduce the strain-dependency of the hysteretic loops. The formulation starts from 1D model, and it is extended into 3D models in infinitesimal and finite deformation regimes. Stress integration algorithms and consistent tangent moduli of those 3D models are also developed. Finally, the visco-elasto-plastic models are combined in parallel with a hyperelastic damage model as a new constitutive model for rubber-like solids. By comparing the proposed model with several experimental data of a rubber, it is found that the model could reproduce behavior of the rubber in various multi-axial deformations under several practical strain rates.
We have developed a method of predicting steel corrosion in reinforced concrete (RC) structures based on the electrochemical approach. The governing equation for the corresponding three-dimensional reaction-diffusion process is endowed with the Neumann boundary conditions involving anodic and cathodic reactions by which oxygen and water are consumed. We demonstrated the capability of the proposed analysis method in predicting the corrosion contents according to environmental conditions. Also, the method is applied for predicting steel corrosion around the joint of a shield tunnel segment and the results are validated in comparison with those of the accelerated test originally devised in this study. Furthermore, it was confirmed that the proposed method enabled us to qualitatively evaluate the effect of reducing the depth of corrosion by applying methods of surface repair and electrolytic protection as countermeasure work against the degradation of RC structures.