Contribution to Theme A of the Benchmark Workshop: Effect of Concrete Swelling on the Equilibrium and Displacements of an Arch Dam

The Kariba dam is undergoing concrete expansion as a result of an alkali-aggregate reaction. The model adopted to simulate the process is explained in the paper; it is based on the model first proposed by Ulm et al, as later modified by Saouma and Perotti. It has been implemented in the commercial finite element code Abaqus and applied to solve the benchmark problem. The parameters of the model were calibrated using the data recorded up to 1995. The calibrated model was then used for predicting the evolution of the dam up to the present date. Apart from this prediction the paper offers a number of conclusions, such as the fact that the stress level appears to have a major influence on the expansion process; and it presents some suggestions to improve the formulation of the benchmark, such as providing temperature data and widening the locations and conditions of the data employed in the calibration

Effect of Concrete Swelling on the Equilibrium and Displacements of an Arch Dam

The Kariba dam is undergoing concrete expansion as a result of an alkali-aggregate reaction. The model adopted to simulate the process is explained in the paper; it is based on the model first proposed by Ulm et al, as later modified by Saouma and Perotti. It has been implemented in the commercial finite element code Abaqus and applied to solve the benchmark problem. The parameters of the model were calibrated using the data recorded up to 1995. The calibrated model was then used for predicting the evolution of the dam up to the present date. Apart from this prediction the paper offers a number of conclusions, such as the fact that the stress level appears to have a major influence on the expansion process; and it presents some suggestions to improve the formulation of the benchmark, such as providing temperature data and widening the locations and conditions of the data employed in the calibration

Identification of pressures and maintenance in railway tunnels

This paper describes an interactive set of tools used to determine the safety of tunnels and to provide data for the decision making of its mainteinance. Although, no doubt, there are still several drawbacks in the difficult procedures in use it is clear that the way is promising and future improvements both in experimental and analytical methods will increase our understanding of this matter.

Flight dynamics and stability of kites in steady and unsteady wind conditions

The flight dynamics and stability of a kite with a single main line flying in steady and unsteady wind conditions are discussed. A simple dynamic model with five degrees of freedom is derived with the aid of Lagrangian formulation, which explicitly avoids any constraint force in the equations of motion. The longitudinal and lateral–directional modes and stability of the steady flight under constant wind conditions are analyzed by using both numerical and analytical methods. Taking advantage of the appearance of small dimensionless parameters in the model, useful analytical formulas for stable-designed kites are found. Under nonsteady wind-velocity conditions, the equilibrium state disappears and periodic orbits occur. The kite stability and an interesting resonance phenomenon are explored with the aid of a numerical method based on Floquet theory.