Lastcombinaties

Lastcombinaties are a concept in structural engineering used to form specific scenarios in which different loads act on a structure simultaneously. By combining the effects of several loading conditions into a finite set of cases, engineers assess how a structure will behave under worst‑case or representative conditions and ensure safety and performance.

The loads involved typically include permanent (dead) loads, variable (live) loads, and environmental actions such as wind, snow, and temperature effects. In some standards seismic actions or construction loads are also considered. The goal is to capture both the magnitude and the interaction of these loads, rather than relying on any single load case.

In design practice, lastcombinaties are part of design codes and standards. They are used for different design objectives, most notably the ultimate limit state (ULS), which concerns strength and stability, and the serviceability limit state (SLS), which concerns deflections, cracking, and overall usability. A deterministic approach is usually followed: a predefined set of load cases, each with specific multipliers or factors, is evaluated, and the most critical combination governs the design. The exact rules and multipliers vary by code and country, with common principles that some loads act simultaneously at their maximum, others at stated partial effects, and some combinations prioritizing different dominant loads.

Standards that address lastcombinaties include Eurocodes, ASCE 7, and national building codes. The concept also accommodates variations such as long-term effects, repeated loads, and accidental or extreme scenarios, depending on the applicable code. In Dutch-language practice, lastcombinaties are a fundamental part of formal design procedures for structural safety and performance.