## Load combinations

LOAD COMBINATIONS In Section 13.2 various forces that are likely to act on the dam have been discussed. But all these forces seldom act simultaneously on the dam. There are some combinations of the loads that may act simultaneously. Design of the dam should be based on the most adverse combination of “probable load condition”. USBR has recommended two load combinations. 1. Standard load combinations. 2. Extreme load combinations. 1. Standard Load Combinations. Under this heading three possible combinations are given. (i) Horizontal water pressure, at normal reservoir level + ice pressure + silt pressure + normal uplift pressure. But this combination is adopted where ice pressure is considerable. (ii) Horizontal water pressure at normal reservoir level + earthquake pressure + silt pressure + normal uplift pressure. (iii) Horizontal water pressure at H.F.L. + silt pressure + normal uplift pressure. 2. Extreme Load Combination. Maximum flood water elevation + silt…