Experimental investigation of built-up double-Z members in bending and compression

Cold-formed steel members have been used extensively in low and midrise residential building construction. The usage of cold-formed steels as primary structural members has been increased due to its high load to weight ratio. Coldformed steel built-up sections are commonly used as compression elements to carry larger loads and over longer spans when a single individual section is insufficient. However, not much research has been done on built-up sections. This paper aims to investigate the compressive capacity of pin-ended cold-formed steel built-up lipped channel sections using finite element analysis (FEA). In the study, cold-formed steel built-up lipped channel consists of two identical C-channel sections oriented back to back with spacing between them and having a ratio of I xx = I yy which are connected by battens at top and at bottom throughout its lengths at regular intervals according to code based provisions. A non-linear finite element model is developed and verified against theoretical results. The thickness of the members is thin and hence they are susceptible to buckling, shell elements S4R are used in FE modeling. The theoretical analysis is based on effective width method and direct strength method and the results are generally conservative for cold-formed steel built-up channel sections.

Section: Literature Reviewmentioning

confidence: 99%

An Investigation of the Compressive Strength of Cold-Formed Steel Built up Channel Sections

Ananthi

Palani

Iyer

2014

“…El Aghoury et al (2012) proposed an empirical equation to calculate the compression load-carrying capacity of battened columns made of four equal slender angles. Georgieva et al (2012a, 2012b, 2012c) carried out experimental and numerical investigations on innovative built-up CFS sections made of U and Z profiles and assessed the applicability of direct strength method ( DSM ) on flexural and compression ultimate capacity of the members and also presented the effect of fastener flexibility on the strength of the built-up CFS members. Piyawat et al (2013) developed an axial load capacity equation for doubly-symmetric built-up cold-formed sections.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on behaviour and design of cold-formed steel built-up column composed of lipped sigma channels

Anbarasu¹

2019

This article aims at investigating the structural response and predicting the ultimate resistance of cold-formed steel built-up columns composed of lipped sigma sections with pinned ends. For this purpose, a numerical model is established by using the finite element code ABAQUS. The finite element models include geometric, material nonlinearity. The effects of initial local and overall geometric imperfections have been taken into consideration in the finite element modelling. The results of the nonlinear finite element analysis were validated with the available experimental results present in the literature. A parametric study was carried out using the developed finite element model to study the effect of member slenderness, height-to-width ratio and depth of trapezoidal stiffener on the ultimate resistance of cold-formed steel closed built-up columns. On the basis of the parametric results, presented herein, appropriateness of the current direct strength method in the North American Specification for cold-formed steel columns is assessed. Based on such comparison, design expression is proposed to provide reliable design strength prediction of cold-formed steel built-up column composed of lipped sigma sections and verified through reliability analysis.

“…El Aghoury et al (2013) investigated the behaviour of built-up columns made of four equal angles and proposed an empirical equation to calculate the compression load carrying capacity of battened columns. Georgieva et al (2012aGeorgieva et al ( , 2012bGeorgieva et al ( , 2012c conducted extensive experimental and numerical study on innovative built-up CFS sections made of U and Z profiles, evaluated the applicability of DSM on flexural and compression capacity of the members and also discussed the flexibility of fasteners' effect on the capacity of the built-up CFS members. Piyawat et al (2013) developed a simplified axial load capacity equation for doubly symmetric built-up cold-formed tubular and Isections subject to both global and distortional buckling.…”

Section: Introductionmentioning

confidence: 99%

Behaviour of cold-formed steel built-up I-section columns composed of four U-profiles

Anbarasu¹,

Venkatesan²

2018

This work reports numerical results concerning the cold-formed steel built-up I-section columns composed of four U-profiles under axial compression. A finite element model is developed by using the software program ABAQUS. The developed model includes geometric, material nonlinearities and geometric imperfections. The finite element model was verified against the experimental results reported in the cold-formed steel built-up open section columns. In the parametric study, the sections are analysed with several cross-sectional dimension ratios and lengths, in order to assess their influence on the buckling behaviour and ultimate strength of cold-formed steel built-up I-section columns. After presenting and discussing the numerical parametric results, the article shows that the current direct strength method in the North American Specification for cold-formed steel compression members design curve fails to predict adequately the ultimate strength of some of the columns analysed and addresses the modification proposed on current direct strength method curves, providing improved predictions of all the numerical ultimate strength available. The proposed method is also assessed by reliability analysis.