The effect of elastic support of web on thermal profiles
Hautala, Janne (2026)
2026
Konetekniikan DI-ohjelma - Master's Programme in Mechanical Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
Hyväksymispäivämäärä
2026-04-10
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202604093805
https://urn.fi/URN:NBN:fi:tuni-202604093805
Tiivistelmä
Cold-formed steel profiles are widely used in the construction industry as members of light-framed structures. Thermal profiles are cold-formed profiles with perforated webs. The perforations create a tortuous path for heat to travel through the web, limiting heat transfer between flanges. They are used in applications where limiting thermal conduction through the structure is desired. Perforating the web also reduces its shear stiffness. As cold-formed profiles are prone to fail via shear buckling of the web, reduction in the web’s shear stiffness decreases the profile’s load carrying capacity. The purpose of this thesis was to study how supporting the thermal web against buckling affects the load carrying capacity of thermal profiles. The support was achieved by encasing the profile in elastic material, elastic in the sense that the supporting material has low stiffness in comparison to the material of the profile. The profile studied here was a Ruukki’s Termo purlin, and the supporting material used was polyisocyanurate (PIR) foam.
The effect of elastic support of web on thermal profiles was studied with use of finite element method (FEM). Prior to this study, experimental research on the supporting of Termo purlin’s web with PIR foam had been conducted at Oxford Institute for Sustainable Development (OISD) at Oxford Brookes University. In this study the numerical FEM model was validated by using the experimental data. With help of the validated FE model, analytical modeling of the behavior of the thermal profile with supported web was studied.
The FE model presented can be used to simulate the behavior of a thermal profile in good agreement with test data. For the thermal profiles studied here, supporting the web with PIR effectively changed the failure mode in bending from shear buckling of the web to buckling of the compressed flange, greatly increasing the load carrying capacity. The analytical model proposed can be used to estimate the load-deflection behavior and load carrying capacity of such a profile in the elastic region.
The effect of elastic support of web on thermal profiles was studied with use of finite element method (FEM). Prior to this study, experimental research on the supporting of Termo purlin’s web with PIR foam had been conducted at Oxford Institute for Sustainable Development (OISD) at Oxford Brookes University. In this study the numerical FEM model was validated by using the experimental data. With help of the validated FE model, analytical modeling of the behavior of the thermal profile with supported web was studied.
The FE model presented can be used to simulate the behavior of a thermal profile in good agreement with test data. For the thermal profiles studied here, supporting the web with PIR effectively changed the failure mode in bending from shear buckling of the web to buckling of the compressed flange, greatly increasing the load carrying capacity. The analytical model proposed can be used to estimate the load-deflection behavior and load carrying capacity of such a profile in the elastic region.