Optimal design of cold-formed steel portal frames for stressed-skin action using genetic algorithm

Phan, Duoc T.; Lim, James B.P.; Tanyimboh, Tiku T.; Wrzesien, Andrzej M.; Sha, Wei; Lawson, R.M.

doi:10.1016/j.engstruct.2015.02.037

Cited by 25 publications

(16 citation statements)

References 17 publications

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“…A design optimization described by Phan et al [4,5] demonstrated that topology can have a significant effect on minimizing the cost of the primary members per meter square of the building. Furthermore, unlike conventional hot-rolled steel portal frames, where the purlin spacing is typically around 1.8 m, with cold-formed steel portal frames there is often a need to have a smaller spacing in order to provide more restraint to the column and rafter members.…”

Section: Notationmentioning

confidence: 99%

Design of Top-hat Purlins for Cold-formed Steel Portal Frames

et al. 2016

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This paper considers the use of cold-formed steel top-hat sections for purlins in the UK, as an alternative to conventional zed-sections. The use of such top-hat sections could be viable for cold-formed steel portal framing systems, where both the frame spacing and purlin span may be smaller than that of conventional hotrolled steel portal frames. Furthermore, such sections are torsionally stiffer than zedsections, and so have a greater resistance to lateral-torsional buckling. They also do not require the installation of anti-sag rods. The paper describes a combination of full-scale laboratory tests and non-linear elasto plastic finite element analyses. The results of twenty-seven tests on four different top-hat sections are presented. In terms of stiffness, good agreement between the experimental and finite element results is shown. The finite element model is then used for a parametric study to investigate the effect of different thicknesses and steel grades. Design recommendations are provided in the form of charts. The use of the finite element method in this way exploits modern computational techniques for an otherwise difficult structural design problem and reduces the need for an expensive and time consuming full laboratory study, whilst maintaining realistic and safe coverage of the important structural design issues. NotationCOV Coefficient of variation; E Young's modulus of elasticity; FEA Finite element analysis; M u EXP Experimental ultimate moment capacity; M u FEA Ultimate moment capacity predicted from finite element analysis; M g,EC3 Gross moment capacity predicted from EC3; M eff,EC3 Effective moment capacity predicted from EC3; t Thickness of section; 0.2  Static 0.2% proof stress; u  Tensile ultimate strength; true  True strain eng  Engineering strain true  True stress eng  Engineering stress 1 Introduction In the UK, single-storey steel portal frames account for approximately 50% of the constructional steel used each year and 90% of all single-storey buildings [1, 2].Such buildings typically use conventional hot-rolled steel sections for the primary column and rafter framing members, which in turn support the secondary coldformed steel purlin and side rail members; these secondary members, in turn, support the cladding.For portal frames of modest span (around 12 m), the introduction of higher strength grades of cold-formed steel into the UK in the past decade, has led to coldformed steel sections being used for the both primary members as well as for the secondary members (see Fig. 1). Such cold-formed steel portal framing systems are now a viable alternative to conventional hot-rolled steel portal framing systems [3].However, unlike conventional hot-rolled steel portal frames in the UK, where the frame spacing is typically 6 m, there is scope to vary the frame spacing in the design of cold-formed steel portal frames. This is because cold-formed steel sections are lighter than hot-rolled steel sections, so structural members can be bolted and erected on site by semi-skilled workers, wit...

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Section: Notationmentioning

confidence: 99%

Design of Top-hat Purlins for Cold-formed Steel Portal Frames

et al. 2016

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“…However, design on a bare frame was carried out, neglecting the serviceability limit state. More recently, Phan et al (2015) and Wrzesien et al (2016) considered the effect of stressed-skin on cladded portal frame buildings. Through focusing only on optimising the material cost of main frame, those researchers have not considered the effect of the material cost of the secondary members (i.e., purlins, side rails and cladding) on the overall cost of the building.…”

Section: Introductionmentioning

confidence: 99%

“…The CFS framing system is designed to both ultimate and serviceability limit states using the The Steel Construction Institute recommendations for deflection limits for portal frames (see Table 1). It should be noted that the length of building is long enough to neglect the stressedskin effect through cladding system (Phan et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Optimum design of cold-formed steel portal frame buildings including joint effects and secondary members

et al. 2017

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“…Technologies 2017, 5, 81 3 of 13 stressed-skin on cladded portal frame buildings is recently considered [15][16][17][18], in which the influence of knee brace joint at eaves was investigated as a fixed configuration. Since GAs are unconstrained optimization techniques, constraint handling approaches therefore play an important role in its implementation.…”

Section: General Description Of Long-span Cold-formed Steel Portal Frmentioning

confidence: 99%

“…Also, influence of pitch of the roof and the frame spacing was investigated in term of topology variables. The effect of stressed-skin on cladded portal frame buildings is recently considered [15][16][17][18], in which the influence of knee brace joint at eaves was investigated as a fixed configuration.…”

Section: Introductionmentioning

confidence: 99%

Design Optimization of Long-Span Cold-Formed Steel Portal Frames Accounting for Effect of Knee Brace Joint Configuration

et al. 2017

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Abstract:The application of cold-formed steel channel sections for portal frames becomes more popular for industrial and residential purposes. Experimental tests showed that such structures with long-span up to 20 m can be achieved when knee brace joints are included. In this paper, the influence of knee brace configuration on the optimum design of long-span cold-formed steel portal frames is investigated. The cold-formed steel portal frames are designed using Eurocode 3 under ultimate limit states. A novel method in handling design constraints integrated with genetic algorithm is proposed for searching the optimum design of cold-formed steel portal frames. The result showed that the proposed routine for design optimization effectively searched the near global optimum solution with the computational time is approximate 50% faster than methods being popularly used in literature. The optimum configuration for knee brace joint can reduce the section size of rafter and so the lighter frame could be obtained especially for long-span portal frame. The minimum weight of main frame obtained from optimization process is approximate 19.72% lighter than a Benchmark Frame used in the full-scale experimental test.

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Optimal design of cold-formed steel portal frames for stressed-skin action using genetic algorithm

Cited by 25 publications

References 17 publications

Design of Top-hat Purlins for Cold-formed Steel Portal Frames

Design of Top-hat Purlins for Cold-formed Steel Portal Frames

Optimum design of cold-formed steel portal frame buildings including joint effects and secondary members

Design Optimization of Long-Span Cold-Formed Steel Portal Frames Accounting for Effect of Knee Brace Joint Configuration

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