Steel Trusses in Industrial Buildings - Load Bearing Capacity and Lateral Buckling Resistance
(2024) In TVSM-5000 VSMM01 20241Structural Mechanics
Department of Construction Sciences
- Abstract
- The dissertation deals with the load-bearing capacity, in terms of stability, of a steel truss in an industrial building. It is based on previous work by Tosovic [1], in which the roof was investigated in the same type of building but the results showed that the trusses were the deficient elements.
Steel trusses are a popular choice of construction for large-span buildings due to their load-bearing capacity over large spans. However, collapse of the building type has occurred on several occasions in recent years, especially in northern Sweden, whereby faulty construction and high snow loads have been identified as potential causes of the collapse. A common truss construction in the Nordic countries was selected for the analysis. The... (More) - The dissertation deals with the load-bearing capacity, in terms of stability, of a steel truss in an industrial building. It is based on previous work by Tosovic [1], in which the roof was investigated in the same type of building but the results showed that the trusses were the deficient elements.
Steel trusses are a popular choice of construction for large-span buildings due to their load-bearing capacity over large spans. However, collapse of the building type has occurred on several occasions in recent years, especially in northern Sweden, whereby faulty construction and high snow loads have been identified as potential causes of the collapse. A common truss construction in the Nordic countries was selected for the analysis. The methodology used Abaqus, a finite element analysis software. Initially, an investigation of modelling methods was carried out with a smaller truss, the purpose of which was to find a model that provided increased efficiency in modelling without sacrificing accuracy in the result.
Using the developed modelling method, the truss was initially constructed with the columns and their connections. The result provided insight into the slenderness and buckling behaviour of the truss. By using Eurocode 3, the reduction factor of the truss was obtained in relation to the theoretical bearing capacity of the material strength.
An industrial building with three trusses and a corrugated steel roof was designed and simulations with three different load cases were used to analyse the behaviour of the building. The first case involved a uniformly distributed load over the entire roof. The other two had a distributed load on half the roof and a horizontal load on one truss to initiate second-order effects. Contrary to previous work by Tosovic [1], all results showed that the roof yielded before the truss. A thicker roof was investigated for all load cases to eliminate eigenvalues when the roof buckles. The result gave an eigenvalue for each case where the trusses buckle.
A parametric study was carried out with a model of a truss using springs along the theoretical connection of the truss to the roof. The study investigated the influence of different spring axial stiffness perpendicular to the truss direction and rotational stiffness around the truss. These are mainly stabilised degrees of freedom by the roof.
The results show that the truss’s design moment capacity, without a roof, can only be utilised about 10%. The reduction factor increased drastically to about 60% when the whole building was examined with a thicker roof.
The parametric study displayed how the axial stiffness of a roof has a greater impact than rotational stiffness on the stability of the structure, along with the influence of rotational stiffness decreasing with higher axial stiffness. Due to difficulties in obtaining values from the buckling analysis, an alternative static analysis was performed where boundary conditions replaced the springs. It resulted in reduction right below 50%. (Less) - Popular Abstract
- Steel trusses, which are commonly used in industrial buildings, are known for their strength and ability to span large distances. Despite their advantages, there have been collapses in buildings using trusses, especially in regions with heavy snowfall. This study concludes that the trusses deform by rotating sideways, known as torsional buckling, when exposed to heavy loads which heavily influences their utilisation possibilities.
To understand the structural failure of these buildings, we analysed a common Nordic design, as seen in the figure below, in collaboration with AFRY by using the advanced finite element analysis software Abaqus. Previous research investigating the building had shown the trusses to be the weakest component,... (More) - Steel trusses, which are commonly used in industrial buildings, are known for their strength and ability to span large distances. Despite their advantages, there have been collapses in buildings using trusses, especially in regions with heavy snowfall. This study concludes that the trusses deform by rotating sideways, known as torsional buckling, when exposed to heavy loads which heavily influences their utilisation possibilities.
To understand the structural failure of these buildings, we analysed a common Nordic design, as seen in the figure below, in collaboration with AFRY by using the advanced finite element analysis software Abaqus. Previous research investigating the building had shown the trusses to be the weakest component, although our findings surprisingly contradicted that conclusion.
The building and components analysed in the investigation. Two major tasks were carried out through the research: comparison of modelling approaches and evaluation of the trusses capacity. A total of four methods were used to evaluate the capacity. Initially, we examined a standalone truss to understand the behaviour of the truss itself. It gave insight into the structure’s slenderness, as it was prone to torsional buckling under lowloading conditions. However, when the truss was modelled with a roof, stability improved drastically.
Different modelling techniques were used to model the influence of the roof. The studies gave mixed results, one given in the following figure, proving the influence of modelling when simulation structural behaviour. It could be concluded that the bolts attaching the roof to the truss limited movement, increasing the truss
utilisation by around sixfold compared to the standalone structure, showing how much the roof impacts the stabilisation of the structure. A parametric study revealed that the axial stiffness of the roof has the most significant impact on overall stability. While rotational stiffness along the truss also contributes, its effect is less crucial.
Result using one of the three methods, where a model consisting of three trusses and the roof was made.
Our study presents several key insights for improving the stability of steel trusses in industrial buildings:
- Roof Impact and Sensitivity: Attaching a roof significantly stabilises the slender truss, increasing its load-bearing capacity. Properly designed roofs are crucial for preventing structural failures, more so since the component seem to fail first.
- Axial vs. Rotational Stiffness: Enhancing the axial stiffness of the roof is more effective than increasing rotational stiffness in preventing buckling.
- Modelling approach: The modelling techniques significantly affected the results of the analyses where different approaches to the roof-truss interaction gave contrasting outcomes.
Our research provides insight into structural failure possibly causing the weakness of the industrial buildings. More so, it proves the importance of modelling approaches and sensitivity analyses when performing simulations. Through continued research, further optimisations could be made on the truss design, and conclusions on the effects of certain modelling choices be drawn. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9170307
- author
- El-Sherif, Adam LU and Gardshol, Hanna LU
- supervisor
-
- Erik Serrano LU
- organization
- course
- VSMM01 20241
- year
- 2024
- type
- H3 - Professional qualifications (4 Years - )
- subject
- keywords
- Civil Engineering, Structural Mechanics, Steel Trusses, Industrial Buildings, Load Bearing Capacity, Lateral Buckling Resistance
- publication/series
- TVSM-5000
- report number
- TVSM-5274
- ISSN
- 0281-6679
- language
- English
- id
- 9170307
- date added to LUP
- 2024-07-16 12:55:39
- date last changed
- 2024-07-16 12:55:39
@misc{9170307,
abstract = {{The dissertation deals with the load-bearing capacity, in terms of stability, of a steel truss in an industrial building. It is based on previous work by Tosovic [1], in which the roof was investigated in the same type of building but the results showed that the trusses were the deficient elements.
Steel trusses are a popular choice of construction for large-span buildings due to their load-bearing capacity over large spans. However, collapse of the building type has occurred on several occasions in recent years, especially in northern Sweden, whereby faulty construction and high snow loads have been identified as potential causes of the collapse. A common truss construction in the Nordic countries was selected for the analysis. The methodology used Abaqus, a finite element analysis software. Initially, an investigation of modelling methods was carried out with a smaller truss, the purpose of which was to find a model that provided increased efficiency in modelling without sacrificing accuracy in the result.
Using the developed modelling method, the truss was initially constructed with the columns and their connections. The result provided insight into the slenderness and buckling behaviour of the truss. By using Eurocode 3, the reduction factor of the truss was obtained in relation to the theoretical bearing capacity of the material strength.
An industrial building with three trusses and a corrugated steel roof was designed and simulations with three different load cases were used to analyse the behaviour of the building. The first case involved a uniformly distributed load over the entire roof. The other two had a distributed load on half the roof and a horizontal load on one truss to initiate second-order effects. Contrary to previous work by Tosovic [1], all results showed that the roof yielded before the truss. A thicker roof was investigated for all load cases to eliminate eigenvalues when the roof buckles. The result gave an eigenvalue for each case where the trusses buckle.
A parametric study was carried out with a model of a truss using springs along the theoretical connection of the truss to the roof. The study investigated the influence of different spring axial stiffness perpendicular to the truss direction and rotational stiffness around the truss. These are mainly stabilised degrees of freedom by the roof.
The results show that the truss’s design moment capacity, without a roof, can only be utilised about 10%. The reduction factor increased drastically to about 60% when the whole building was examined with a thicker roof.
The parametric study displayed how the axial stiffness of a roof has a greater impact than rotational stiffness on the stability of the structure, along with the influence of rotational stiffness decreasing with higher axial stiffness. Due to difficulties in obtaining values from the buckling analysis, an alternative static analysis was performed where boundary conditions replaced the springs. It resulted in reduction right below 50%.}},
author = {{El-Sherif, Adam and Gardshol, Hanna}},
issn = {{0281-6679}},
language = {{eng}},
note = {{Student Paper}},
series = {{TVSM-5000}},
title = {{Steel Trusses in Industrial Buildings - Load Bearing Capacity and Lateral Buckling Resistance}},
year = {{2024}},
}