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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

Table 1:

Structural components notations

Component NotationComponent FailureComponent NotationComponent Failure
x1Flexural failureBeam failurex5Floor system failure
x2Shear failurex6Base Plate failure
x3Bolts failurex7Stability failureColumn failure
x4Weld failurex8Material failure
Table 2:

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}
Table 3:

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
Figure 5:

Constraints violation and final objective function for frame system elements

Table 4:

Objective function and constraints violation of the whole unified system

IterationsObjective FunctionConstraints Violation
03114.320.3029
12983.310
22438.80
32435.230
Table 5:

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
Table 6:

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
Figure 6:

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

DOI: https://doi.org/10.2478/cee-2026-0055 | Journal eISSN: 2199-6512 (formerly 1336-5835) | 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.