This paper demonstrates ways of finding the optimal design of an arch dam with relatively little expenditure of time.

The arch dam is situated at the Euphrates in Turkey. The dam has a volume of 2.0 million m and is 173 m in height.

This paper compares results obtained by theory of thin shells (difference method of the final design), model test, and the finite element program FLASH2. For the sake of brevity, only the load cases self-weight and hydrostatic pressure are covered. The cases buoyancy, temperature, seismic load, shrinkage, and creep could be taken into ac-count as well.

The program was later on extended with the following options:

- automatic input of geometry and load;
- plot possibilities for the presentation of radial and tangential deformations on the girthed shear surface;
- lines of equal concrete quality in function of a linear elastic failure criterion and spread of the concrete qualities on the building site
- consideration of seismic load according to Westergaard

The program was calibrated using long term control measurements of several older, very large arch dams.

The program POST which describes the post cooling process of fresh dam concrete is also part of the program system. It predicts temperatures on any point of the concrete, seasonal outlet temperatures in the cooling pipes, and residual stress on any point of the concrete. This thermodynamic program was calibrated using long term studies of a large gravity dam in Switzerland. This finite difference program can fulfil any arbitrary boundary conditions. With the help of this program it can be determined that a favourable horizontal compressive prestressing of the dam body of about 15 kp/cm2 can be achieved by artificial post cooling. With this method of cooling, the seasonal mean concrete temperatures in the middle plane of the dam rise over time to the long term annual mean of the ambient air temperature. As op-posed to natural cooling, with which the seasonal mean concrete temperatures in the middle plane of the dam fall over time to the long term annual mean of the ambient air temperature. Since the dam will contract using natural cooling, there is a risk of joints between certain cast-ing segments (monoliths) partially opening

2. Method of Calculation and Theory