Assessment Of Monar Arch Dam UnderExtreme Seismic And Thermal Loads

Abstract

Monar dam is a double-curvature concrete arch dam in the north west of the UK constructed in the early 1960s. This paper examines the elastic response of the dam under seismic and temperature loads using a 3-dimensional finite element model that takes into account dam-foundation-water interactions. Seismic loads are applied in three main orthogonal directions using synthetic ground motions, while temperature load is based on minimum and maximum mean daily ambient air temperatures at the site. Additionally a temperature gradient exists through the thickness of the dam between the upstream and downstream faces. The study shows that temperature has a significant role in determining the final stress distribution within the dam. The results indicate that for summer loadcases a band of high tensile stress is developed on the downstream face near to the dam/rock interface. The addition of the seismic loading increases the tensile stresses from the normal summer loading by a relatively modest amount. This might, however, be sufficient to cause the development of significant cracking.