Analysis of Buttress Dams

With the improvement in the designs of these dams, the apparent flaws have also surfaced, which are being tackled, at individual level……(Chadwick, Introduction to Buttress Dams)An American engineer used such type of dam construction in his projects during the 20th Century and hence, these dams are also called Ambursen dams. The terrain condition is also responsible for choosing the building of this type of dams as the land at the particular site may not be able to support the size and weight of other types of dams. As the name suggests, the dam has the support of many buttresses at different intervals, while these are concrete slabs with reinforced steel that act as a strong seal against the flow of water from the water bodies like a river. As buttress dams can be of many types, the two main types are flat slab and multiple arch dams.While in the flat slab type dams, the flat front faces the water upstream. in multiple types, the front of the dam has several arches which face the upstream. A picture of this dam is given in the Annexure, at the end of this paper, as figure 1.Buttress normally is a structure, which has a composition of a system of curved beams. Each beam in such a composition is responsible for transmitting part of the water load and its dead weight to the dam foundation. The columns are proportioned in such a way that they develop uniform compressive stress, while they should be curved to avoid any load being eccentric at a particular point. Buttresses of large dams are normally built with contraction joints, which caters to the development of secondary tensile stress in the structure….(Buttresses)While discussing the physics involved in designing the buttress dams, the concerned engineers consider the same forces here as they would do while building an arch or a gravity dam. Accordingly, three types of forces would come into play while building a buttress dam. These are the forces exerted by the water and concrete plus the normal force exerted in the upward direction by the earth.