Reinforcement Schemes for Cold-Formed Steel Joists with a Large Web Opening in Flexural Zone - An Experimental Investigation

Flexural Strength ◽

North American ◽

Web Openings ◽

Reinforcement Scheme ◽

Web Opening ◽

The objective of this investigation is to develop an economical and an efficient reinforcement scheme for large web openings in cold-formed steel (CFS) joists in flexural zones that would restore the original moment resistance of the section. This investigation considered commonly used floor joists in North American CFS construction. Tests on joists webs with no openings and with large circular and square openings located at the mid-depth revealed that large openings may reduce the flexural strength by 23%. A reinforcement scheme consisting of screw fastening of 31.75 mm x 12.7 mm (1-1/2”x1/2”) bridging channels having matching thickness as of the receiving joist, along the compression and the tensile edges of the opening utilizing a screw spacing of 31.75 mm was established. Three identical tests utilizing the proposed reinforcement scheme restored the corresponding flexural strengths of the CFS section under consideration, and the failure locations were outside the reinforced opening regions.

Reinforcement schemes for cold-formed steel joists with a large web opening in shear zone—An experimental investigation

Thin-Walled Structures ◽

10.1016/j.tws.2013.06.011 ◽

2013 ◽

Vol 72 ◽

pp. 28-36 ◽

Cited By ~ 5

Author(s):

Sandesh R. Acharya ◽

K.S. Sivakumaran ◽

Ben Young

Keyword(s):

Shear Zone ◽

Web Opening ◽

Experimental Investigation of Cold-Formed Steel Tubes Subjected to Web Crippling

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.166-169.322 ◽

2012 ◽

Vol 166-169 ◽

pp. 322-328

Author(s):

Huai Lin Peng ◽

Feng Zhou ◽

Le Wei Tong

Keyword(s):

North American ◽

Steel Sheet ◽

Steel Structures ◽

Steel Tubes ◽

Concentrated Load ◽

Web Crippling ◽

European Code ◽

Cold Formed Steel ◽

The Web

A series of tests on cold-formed steel square and rectangular hollow sections subjected to web crippling is reported in this paper. The web crippling tests were conducted under two loading conditions of end-two-flange (ETF) and interior-two-flange (ITF), which are specified in the current North American Specification for cold-formed steel structures. The concentrated load was applied by means of bearing plates, which act across the full flange width of the specimen sections. Different bearing lengths were investigated. The test specimens were fabricated by cold-rolling from steel sheet with nominal yield strength of 345MPa. The measured web slenderness values of the tubes ranged from 15.5 to 46.0. The test strengths obtained from this study are compared with the design strengths obtained using the current North American Specification, Australia Standard, European Code and Chinese Code for cold-formed steel structures. It is shown that the design strengths predicted by the specifications are either unreliable or too conservative.

BEHAVIOR OF FULLY ENCASED COLD FORMED STEEL JOISTS WITH/WITHOUT WEB OPENINGS: EXPERIMENTAL INVESTIGATION

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2018.11 ◽

2018 ◽

Vol 5 (1) ◽

Author(s):

Hanadi Elkhansa ◽

Adnan Masri ◽

Zaher Abou Saleh

Keyword(s):

Energy Absorption ◽

Failure Modes ◽

Load Capacity ◽

Composite Beams ◽

Absorption Capacity ◽

Cross Sectional ◽

Web Openings ◽

Flexural Failure ◽

This paper presents an experimental investigation on the behavior of encased light cold-formed steel joists with/without web openings. The study is carried on two sets of composite beams constructed of cold-formed steel joists using I-beam built-up sections. The first set has no web openings while the second set has circular web openings. Each set consists of three beams with various steel section-concrete reinforcing ratio. The constant parameters included in this study are the cross sectional area of the specimen, distribution of web openings in the encased steel I-joist, and the compressive strength of concrete. The tests have been conducted by applying two concentrated identical loads. Consequently, a comparative study is carried out to compare between the behavior of specimens within one set, and a comparison between the specimens of the two sets. This comparison is related to strength, stiffness, ductility, energy absorption capacity and failure modes. Based on the testing results, it is concluded that, the load capacity of the composite beams without web openings is greater than that with web openings for the same steel ratio. But the existence of web openings in the encased steel joists enhances the ductility and the energy absorption of the composite beams. Also using cold formed steel I-joists in the composite beams allow the failure mode to be ductile flexural failure.

Flexural strength of cold-formed steel joists with reinforced web openings

Canadian Journal of Civil Engineering ◽

10.1139/l06-064 ◽

2006 ◽

Vol 33 (9) ◽

pp. 1195-1208 ◽

Cited By ~ 7

Author(s):

K S Sivakumaran ◽

Ming Yin Ng ◽

Steven R Fox

Keyword(s):

Flexural Strength ◽

Local Buckling ◽

Cost Effective ◽

Base Thickness ◽

Web Openings ◽

Face To Face ◽

Cold Formed Steel ◽

Large Opening ◽

Flexural Tests ◽

Effective Reinforcement

The floor joists of cold-formed steel (CFS) structures often require large web openings. Reinforcement of such openings may mitigate the detrimental effects of such web openings. This paper is based on an experimental investigation that considered 203 mm deep (base thickness 1.89 mm) galvanized, lipped channel sections with circular, square, and rectangular openings and two associated reinforcement schemes (screw fastening of 31.8 mm × 1.1 mm thick bridging channel). Since the focus of this investigation was on the flexural strength of such joists, the test specimens were simply supported and were subjected to two equal point loads at equal distance from the supports. Two lipped channel sections were set face-to-face to form the test specimen assembly. Based on 11 sets of three identical flexural tests, it was determined that (i) the tension zones of the web with a large opening need not be reinforced, (ii) closely spaced screw fastening of reinforcements (bridging channel) is essential, and (iii) the reinforcements need to be fastened as close as possible to the compression edges of the opening to minimize local buckling of these edges. This paper demonstrates that it is possible to establish cost-effective reinforcement schemes for CFS sections with large web openings.Key words: cold-formed steel, joists, flexural strength, web openings, reinforcements, experimental.

Experimental investigation of post-fire mechanical properties of Q235 cold-formed steel

Thin-Walled Structures ◽

10.1016/j.tws.2020.106651 ◽

2020 ◽

Vol 150 ◽

pp. 106651 ◽

Cited By ~ 2

Author(s):

Chong Ren ◽

Liusi Dai ◽

Yuner Huang ◽

Wenfu He

Keyword(s):

Mechanical Properties ◽

Experimental investigation of cold-formed steel channels with slotted webs in shear

Thin-Walled Structures ◽

10.1016/j.tws.2016.01.012 ◽

2016 ◽

Vol 102 ◽

pp. 30-42 ◽

Cited By ~ 15

Author(s):

N.V. Degtyareva ◽

V.V. Degtyarev

Keyword(s):

Experimental investigation of concrete-filled cold-formed steel elliptical stub columns

Tubular Structures XVI ◽

10.1201/9781351210843-14 ◽

2017 ◽

pp. 109-115 ◽

Cited By ~ 3

Author(s):

S. Yi ◽

B. Young

Keyword(s):

Cold Formed Steel ◽

Stub Columns

Buckling behavior of cold-formed steel columns at both ambient temperature and simulated fire conditions

Fire Research ◽

10.4081/fire.2017.16 ◽

2016 ◽

Author(s):

Hélder D. Craveiro ◽

João Paulo C. Rodrigues ◽

Luís M. Laím

Keyword(s):

Ambient Temperature ◽

Cross Sections ◽

Failure Modes ◽

Steel Columns ◽

Buckling Behavior ◽

Wide Range ◽

Cold Formed Steel ◽

Simulated Fire ◽

Fire Conditions

Cold-formed steel (CFS) profiles with a wide range of cross-section shapes are commonly used in building construction industry. Nowadays several cross-sections can be built using the available standard single sections (C, U, Σ, etc.), namely open built-up and closed built-up cross-sections. This paper reports an extensive experimental investigation on the behavior of single and built-up cold-formed steel columns at both ambient and simulated fire conditions considering the effect of restraint to thermal elongation. The buckling behavior, ultimate loads and failure modes, of different types of CFS columns at both ambient and simulated fire conditions with restraint to thermal elongation, are presented and compared. Regarding the buckling tests at ambient temperature it was observed that the use of built-up cross-sections ensures significantly higher values of buckling loads. Especially for the built-up cross-sections the failure modes were characterized by the interaction of individual buckling modes, namely flexural about the minor axis, distortional and local buckling. Regarding the fire tests, it is clear that the same levels of restraint used in the experimental investigation induce different rates in the generated restraining forces due to thermal elongation of the columns. Another conclusion that can be drawn from the results is that by increasing the level of restraint to thermal elongation the failure of the columns is controlled by the generated restraining forces, whereas for lower levels of restraint the temperature plays a more important role. Hence, higher levels of imposed restraint to thermal elongation will lead to higher values of generated restraining forces and eventually to lower values of critical temperature and time.