scholarly journals Serviceability and flexural strength of lightweight floor made of cold formed steel joists.

2021 ◽  
Author(s):  
Quzzafi Rehman
Keyword(s):  
Finite Element ◽  
Flexural Strength ◽  
Ultimate Strength ◽  
Parametric Study ◽  
Finite Element Modelling ◽  
Dynamic Properties ◽  
Element Modelling ◽  
Floor Systems ◽  
Cold Formed Steel ◽  
Experimental Findings

The use of cold-formed steel (CFS) is becoming popular in residential and commercial building as a cost-effective alternative to traditional wood materials. CFS provides high strength-to-weight ratio, resulting in permitting lighter structure and longer spans. If proper design considerations are not made, this longer span and lighter structure can result in vibration serviceability issues that may affect building occupant comfort. The available design methods to calculate the dynamic properties of floor systems (i.e. Canadian Wood Council Method, CWC; Applied Design Council Design Method, ATC; and Eurocode, EC5) are used for the design of light-frame timber-based systems, CFS C-shape joists, and structural steel and concrete floor systems. The applicability of such methods to I-shape CFS joists is as yet unavailable. In addition, the North American Code for Cold-formed Steel structural Members (CSA-S136-07) provides specifications of ultimate and serviceability limit state design of C-shape joists rather than I-shape joists. As such, this research was divided into three parts. Part 1 presented the results of laboratory and field study on the vibration of a recently developed CFS I-shape joist called “iSPAN.” The main objective of the first part was to understand the dynamic characteristics of iSPAN floor system, recommend an adequate model for predicting the dynamic response and modal properties of floor systems, and correlate its results with engineered wood I-joists in order to aid the design process. Part 2 presented comparison between the experimental findings and available code provisions for the design of CFS joists at ultimate and serviceability limit states. The effect of web utility holes was also considered on the dynamic properties, and ultimate strength of iSPAN joists. Part 3 presented a finite-element modeling and its verification with the experimental findings of the tested samples. Also, part 3 extended the finite element modelling to analyse I- and C-shape CFS joists to determine their ultimate strength and serviceability, with and without the presence of utility holes in the webs. Since CSA-S137-07 does not provide design provisions for the edge-stiffened (i.e. lipped) holes, a practical-design-oriented parametric study, using the finite-element modelling, was conducted on CFS I- and C-shape members with circular, slotted and tri-slotted, edge-stiffened, holes under flexural loading. The optimized profile of the edge-stiffened holes was obtained using the elastic-buckling analysis. The post-buckling finite-element analysis was then utilized to determine member flexural strength as affected by utility hole geometry and web depth. Results showed that the edge-stiffened holes can significantly improve the flexural strength of CFS joists. The data generated from the parametric study was used to develop new design provisions to predict the flexural strength of such joists with the presence of edge-stiffened holes.

scholarly journals Serviceability and flexural strength of lightweight floor made of cold formed steel joists.

2021 ◽  
Author(s):  
Quzzafi Rehman
Keyword(s):  
Finite Element ◽  
Flexural Strength ◽  
Ultimate Strength ◽  
Parametric Study ◽  
Finite Element Modelling ◽  
Dynamic Properties ◽  
Element Modelling ◽  
Floor Systems ◽  
Cold Formed Steel ◽  
Experimental Findings

The use of cold-formed steel (CFS) is becoming popular in residential and commercial building as a cost-effective alternative to traditional wood materials. CFS provides high strength-to-weight ratio, resulting in permitting lighter structure and longer spans. If proper design considerations are not made, this longer span and lighter structure can result in vibration serviceability issues that may affect building occupant comfort. The available design methods to calculate the dynamic properties of floor systems (i.e. Canadian Wood Council Method, CWC; Applied Design Council Design Method, ATC; and Eurocode, EC5) are used for the design of light-frame timber-based systems, CFS C-shape joists, and structural steel and concrete floor systems. The applicability of such methods to I-shape CFS joists is as yet unavailable. In addition, the North American Code for Cold-formed Steel structural Members (CSA-S136-07) provides specifications of ultimate and serviceability limit state design of C-shape joists rather than I-shape joists. As such, this research was divided into three parts. Part 1 presented the results of laboratory and field study on the vibration of a recently developed CFS I-shape joist called “iSPAN.” The main objective of the first part was to understand the dynamic characteristics of iSPAN floor system, recommend an adequate model for predicting the dynamic response and modal properties of floor systems, and correlate its results with engineered wood I-joists in order to aid the design process. Part 2 presented comparison between the experimental findings and available code provisions for the design of CFS joists at ultimate and serviceability limit states. The effect of web utility holes was also considered on the dynamic properties, and ultimate strength of iSPAN joists. Part 3 presented a finite-element modeling and its verification with the experimental findings of the tested samples. Also, part 3 extended the finite element modelling to analyse I- and C-shape CFS joists to determine their ultimate strength and serviceability, with and without the presence of utility holes in the webs. Since CSA-S137-07 does not provide design provisions for the edge-stiffened (i.e. lipped) holes, a practical-design-oriented parametric study, using the finite-element modelling, was conducted on CFS I- and C-shape members with circular, slotted and tri-slotted, edge-stiffened, holes under flexural loading. The optimized profile of the edge-stiffened holes was obtained using the elastic-buckling analysis. The post-buckling finite-element analysis was then utilized to determine member flexural strength as affected by utility hole geometry and web depth. Results showed that the edge-stiffened holes can significantly improve the flexural strength of CFS joists. The data generated from the parametric study was used to develop new design provisions to predict the flexural strength of such joists with the presence of edge-stiffened holes.

Numerical Study of the Effect of Geometry and Boundary Conditions on the Collapse Behaviour of Stocky Stiffened Panels

2012 ◽  
Vol 154 (A2) ◽  
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Ultimate Strength ◽  
Material Properties ◽  
Finite Element Modelling ◽  
Numerical Study ◽  
Fe Analysis ◽  
Stiffened Panels ◽  
Element Modelling ◽  
Geometric Configurations

This study aims at studying different configurations of the stiffened panels in order to identify robust configurations that would not be much sensitive to the imprecision in boundary conditions that can exist in experimental set ups. A numerical study is conducted to analyze the influence of the stiffener’s geometry and boundary conditions on the ultimate strength of stiffened panels under uniaxial compression. The stiffened panels with different combinations of mechanical material properties and geometric configurations are considered. The four types of stiffened panels analysed are made of mild or high tensile steel and have bar, ‘L’ and ‘U’ stiffeners. To understand the effect of finite element modelling on the ultimate strength of the stiffened panels, four types of FE models are investigated in FE analysis including 3 bays, 1/2+1+1/2 bays, 1+1 bays and 1 bay with different boundary conditions.

The Effects of Crack Growth History on Fracture Toughness

2019 ◽  
Author(s):  
M. A. Probert ◽  
H. E. Coules ◽  
C. E. Truman ◽  
M. Hofmann
Keyword(s):  
Fracture Toughness ◽  
Finite Element ◽  
Crack Growth ◽  
Parametric Study ◽  
Finite Element Modelling ◽  
Crack Tip ◽  
High Yield ◽  
Element Modelling ◽  
History Effects ◽  
Apparent Fracture Toughness

Abstract The introduction of cracks into loaded versus unloaded components has a significant effect on the apparent fracture toughness within finite element modelling. The history effects of crack introduction can be beneficial to defect assessment procedures that do not consider prior plasticity specifically from crack introduction. It is assumed that as strain energy is released due to plastic deformation during crack formation a reduction in the energy available for crack propagation under fracture conditions is experienced. This can be characterized by the formation of a plastic wake behind the crack tip and leads to significant increases in load at critical J and other crack growth parameters for modelling situations. However experimental evidence validating this apparent fracture toughness increase are needed. A beneficial increase in apparent fracture toughness can prolong the life of components that might be taken out of service prematurely if history effects are not considered. This paper discusses a series of experimental and modelling approaches that have been taken to assess the magnitude of the benefit in increase of apparent fracture toughness by the manipulation of crack introduction history effects. An initial parametric study of material properties on the effect of introducing cracks into loaded and unloaded components indicates that most benefit be derived from high hardness, high yield materials such as Aluminum 7000 series alloys. Further work has been carried out with experimental C(T) specimens of Aluminum Alloy 7475 T7351. Cracks were introduced by fatigue into the samples. One set of specimens was fatigued with a low mean load and the other with a high mean load, this was achieved by keeping a consistent ΔKI between specimens and changing the load ratio one set of specimens. Fracture test results indicate that the influence of prior plasticity on fracture initiation is much subtler in experimental trials than in the finite element model. Crack growth resistance curves and neutron diffraction results measuring the residual stress created ahead of the crack tip by this method are be discussed and contrasted with the parametric study and finite element modelling of the two different crack introduction scenarios.

Finite Element Investigation on Ultimate Strength of Bolted Connections

2012 ◽  
Vol 166-169 ◽  
pp. 1157-1163
Author(s):  
Wael Elleithy ◽  
Choon Kiat Lim
Keyword(s):  
Finite Element ◽  
Ultimate Strength ◽  
Finite Element Modelling ◽  
Stress Distributions ◽  
Bolted Connections ◽  
Element Analysis ◽  
Bolted Connection ◽  
Element Modelling ◽  
Load Distributions ◽  
The Finite Element Analysis

In this paper, the ultimate behaviour of bolted connections and the effect of various configurations of bolted connections on the ultimate strength are thoroughly investigated. Through finite element modelling, the stress distributions, bolt load distributions, and the effect of bolt sizes and bolt arrangements are studied in detail. The finite element analysis results show that the square shape arrangement of a bolted connection has a higher ultimate strength than that of the diamond shape arrangement. The ultimate strength of bolted connection increases as the bolts size increase until a limitation of improvement in strength is reached.

NUMERICAL STUDY OF THE EFFECT OF GEOMETRY AND BOUNDARY CONDITIONS ON THE COLLAPSE BEHAVIOUR OF STOCKY STIFFENED PANELS

2021 ◽  
Vol 154 (A2) ◽  
Author(s):  
M C Xu ◽  
C Guedes Soares
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Ultimate Strength ◽  
Material Properties ◽  
Finite Element Modelling ◽  
Numerical Study ◽  
Fe Analysis ◽  
Stiffened Panels ◽  
Element Modelling ◽  
Geometric Configurations

This study aims at studying different configurations of the stiffened panels in order to identify robust configurations that would not be much sensitive to the imprecision in boundary conditions that can exist in experimental set ups. A numerical study is conducted to analyze the influence of the stiffener’s geometry and boundary conditions on the ultimate strength of stiffened panels under uniaxial compression. The stiffened panels with different combinations of mechanical material properties and geometric configurations are considered. The four types of stiffened panels analysed are made of mild or high tensile steel and have bar, ‘L’ and ‘U’ stiffeners. To understand the effect of finite element modelling on the ultimate strength of the stiffened panels, four types of FE models are investigated in FE analysis including 3 bays, 1/2+1+1/2 bays, 1+1 bays and 1 bay with different boundary conditions.

Experiments and finite element modelling of screw pattern of self-drilling screw connections for high strength cold-formed steel

2019 ◽  
Vol 145 ◽  
pp. 106393 ◽  
Author(s):  
Krishanu Roy ◽  
Hieng Ho Lau ◽  
Tina Chui Huon Ting ◽  
Rehan Masood ◽  
Ankur Kumar ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
High Strength ◽  
Element Modelling ◽  
Cold Formed Steel

Parametric Study of Concentrated Contact of Rigid Indenter with Elastic-Plastic Material

2016 ◽  
Vol 368 ◽  
pp. 29-32
Author(s):  
Dušan Zíta ◽  
Jaroslav Menčík
Keyword(s):  
Finite Element ◽  
Rigid Body ◽  
Rough Surface ◽  
Parametric Study ◽  
Finite Element Modelling ◽  
Plastic Material ◽  
Contact Problems ◽  
Element Modelling ◽  
Elastic Plastic ◽  
Elastic Plastic Material

This paper shows the results of finite element modelling of contact problems between perfectly rigid body with rough surface and an indenter from elastic-plastic material. In the first phase, spherical indenter from elastic – plastic material is considered, which is pressed into a body with a rough surface. Results show the influence of the amplitude and distances of various undulations at the rough surface to response surface.

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