Nachlast

Nachlast is a term used in German-language engineering to denote a load that is applied after an initial or reference state. The word combines nach- meaning after and Last meaning load, and it describes loads that arise later in time or in a sequence rather than being present from the outset.

The concept is used across disciplines to indicate additional loading that must be considered beyond the primary or starting load. In structural and civil engineering, Nachlast refers to subsequent loads that affect a structure during its life, such as loads from operation, environmental changes, or time-dependent effects that accumulate after the initial construction. In geotechnical and foundation-related contexts, the term can describe extra pressures that develop after excavation, backfilling, or other alterations to the soil and loading conditions, which influence the stress state on foundations and retaining elements.

In design practice, Nachlast is typically treated as part of load combinations used to verify safety and performance. Engineers assess how these post-application loads interact with existing loads, apply appropriate safety factors, and ensure that the structure or component can tolerate the cumulative effects over its service life. Identifying potential sources of Nachlast involves analyzing the sequence of events, anticipated changes in use, and environmental or operational conditions that unfold after the initial state.

Terminology varies by field and standard, but the core idea remains: Nachlast denotes an additional or later-applied load that must be accounted for in calculation, verification, and maintenance planning to ensure reliability and safety.

See also Last (load), load combinations, and safety factors in engineering design.