It is convenient to classify individual loads as primary, secondary, or
exceptional. Classification in this manner assists in the proper appreciation
of load combinations to be considered in analysis. The classification is made
in terms of the applicability and/or the relative importance of the load.
- Primary loadsare identified as universally applicable and of prime
importance to all dams, irrespective of type, e.g. water and related
seepage loads, and self-weight loads.
- Secondary loadsare generally discretionary and of lesser magnitude
(e.g. sediment load) or, alternatively, are of major importance only
to certain types of dams (e.g. thermal effects within concrete dams).
- Exceptional loadsare so designated on the basis of limited general
applicability or having a low probability of occurrence (e.g. tectonic
effects, or the inertia loads associated with seismic activity).
1.7.2 Schedule of loads
The primary loads and the more important secondary and exceptional
sources of loading are identified schematically on Fig. 1.8, a gravity dam
section being used for this purpose as a matter of illustrative convenience.
Quantification of loads is left to Chapters 2 and 3.
Not all the loads identified may be applicable to a specific dam; an
element of discretion is left in formulating combinations of loading for
analysis.
36 ELEMENTS OF DAM ENGINEERING
Fig. 1.8 Schematic of principal loads: gravity dam profile
