Lars Jorgenson

• Danish

Lars Jorgensen was born in Denmark in 1876 and received his engineering education in Germany. He immigrated to the United States at the turn of the century and worked briefly as a draftsman at General Electric in Schenectady, New York. By 1903 Jorgensen had relocated to Los Angeles and an engineering position with Edison Electric. In 1905 he moved to Pacific Gas and Electric in San Francisco, and was there for two years. He joined the engineering consulting firm of F. G. Baum in 1907 and remained there until 1914, when he founded his own firm, the Constant Angle Arch Dam Company. Jorgensen patented the concept of the constant angle arch dam, a type of thin arch dam which was reportedly both stronger and more economical to construct than a thin arch constant radius dam. He based the constant-angle arch dam upon the fact that in a constant radius - i.e., a simple cylindrical section - arch dam, there would be only one arch near the top of the dam that was the correct shape for true arch action and stability. The other sections would have central angles which were either too large or too small. A constant-angle arch dam utilizes the principle of drawing correct arches for each contour level and then stacking them to form a dam. If the dam is a tall one, this can result in the top sections overhanging the bottom. To the observer the resulting structure thus resembles a section of a cone or an ellipsoid rather than a section of a cylinder. - HAER No WA-24