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Structural Importance Factor Effect on Reliability-Based Design of Steel Frame System Units: Dependent and Independent Failure Cover

Structural Importance Factor Effect on Reliability-Based Design of Steel Frame System Units: Dependent and Independent Failure

Open Access
|Jun 2026

Figures & Tables

Figure 1:

Solution methodology flow chart

Figure 2:

Frame system units

Figure 3:

Fault tree diagram for the frame system unit

Figure 4:

Reliability block diagram for the frame system unit

Figure 5:

Constraints violation and final objective function for frame system elements

Figure 6:

Survivor function of frame system unit with time including and excluding the structural importance factor effect

Structural components notations

Component NotationComponent FailureComponent NotationComponent Failure
x1Flexural failureBeam failurex5Floor system failure
x2Shear failurex6Base Plate failure
x3Bolts failurex7Stability failureColumn failure
x4Weld failurex8Material failure

The importance of component (1) for a three-system component (Rausand & Hoyland, 2003)

(.,x2,x3)ϕ(1, x2, x3) − ϕ(0, x2, x3)C(11,x2,x3)
(.00)0
(.01)1{1,3}
(.10)1{1,2}
(.11)1{1,2,3}

Objective function and constraints violation of the whole unified system

IterationsObjective FunctionConstraints Violation
03114.320.3029
12983.310
22438.80
32435.230

Survivor function with and without the importance factor

Time UnitSurvivor function without the importance factor effectSurvivor function with importance factor effect% Reduction due to the importance factor impact
011NA
0.50.69590.626610 % lower
10.403750.313322.5 % lower
1.50.20740.1318636.5 % lower
20.09270.049447 % lower

Importance factor effect on optimally designed frame system components

Frame componentsIndependent Failure of separated componentsIndependent Failure of the whole system% Difference
1Number of the studs4345−4.65
2Diameter of the stud [in]0.56040.510.778
3Plastic section modulus of the beam [in3]245.7245.70.0
4Cross-sectional area of the beam [in2]4.14.3−4.878
5Moment of inertia of the beam [in4]1885.31885.4−0.0053
6Moment of inertia of the column [in4]89.238389.20.0429
7Cross-sectional area of the column [in2]2322.90.435
8Base plate width [in]14.716914.42.153
9Base plate length [in]14.758215.44.348
10Base plate thickness [in]1.36271.34.6

The importance of all the components for the frame system

ComponentComponent importance Bϕ(xn)ComponentComponent importance Bϕ(xn)
x10.0234375x50.3515625
x20.0234375x60.3515625
x30.0234375x70.1171875
x40.0234375x80.1171875
DOI: https://doi.org/10.2478/cee-2026-0055 | Journal eISSN: 2199-6512 | Journal ISSN: 1336-5835
Language: English
Page range: 833 - 850
Submitted on: Sep 26, 2025
Accepted on: Oct 27, 2025
Published on: Jun 19, 2026
Published by: University of Žilina
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year

© 2026 Baraa J. M. Al-Eliwi, Rabi M. Najem, James H. Haido, Sevar Dilkhaz Salahaddin, published by University of Žilina
This work is licensed under the Creative Commons Attribution 4.0 License.