Structural Analysis Wiki

The Dlubal Structural Analysis Wiki explains technical terms used in structural analysis and design. The terms are given in alphabetical order and are usually used in Dlubal Software.

836x

000264

2025-02-18

HOAI

Joint Group

Keyboard Functions

Quadrangle Surface

ULS – Ultimate Limit State

ULS stands for "Ultimate Limit State" and describes the state in which the structural component under consideration is subjected to the most unfavorable load.

The ultimate limit state design is used to ensure the stability of structural components. Exceeding this limit state may lead to the failure of the structure.

The Eurocode distinguishes various design situations for the action combinations of the ultimate limit state:

Permanent and transient action E_d

E_{d} = \sum_{j \geq 1} γ_{G, j} \cdot E_{Gk, j} + γ_{Q, 1} \cdot E_{Qk, 1} + \sum_{i > 1} γ_{Q, i} \cdot ψ_{0, i} \cdot E_{Qk, i}

E_d	Design value of loading for permanent and transient actions
γ	Safety factor
ψ	Combination coefficient

Action Combination for Permanent and Transient Loading

Accidental action E_dA

E_{dA} = \sum_{j \geq 1} γ_{GA, j} \cdot E_{Gk, j} + E_{Ad} + γ_{QA, 1} \cdot ψ_{1, 1} \cdot E_{Qk, 1} + \sum_{i > 1} γ_{QA, i} \cdot ψ_{2, i} \cdot E_{Qk, i}

E_dA	Design loading value for accidental loading
γ	Safety factor
ψ	Combination coefficient

Combination of Actions for Accidental Loading

Loading due to earthquake E_d

E_{d} = \sum_{j \geq 1} G_{k, j} " + " P " + " A_{Ed} " + " \sum_{i \geq 1} ψ_{2, i} \cdot Q_{k, i}

G_k,j	Characteristic value of the permanent action j
P	Governing representative value of prestress
A_Ed	Design value of a seismic load
Q_k,i	Characteristic value of a non-governing variable action i (a secondary action)
'+'	"is to be combined"
∑	"common effect of"

Seismic Design Situation

In RFEM and RSTAB, it is possible to automatically generate load combinations based on a design situation for various loads according to the Eurocode.