A Computer Program for the Analysis and Design of Composite Timber-Steel Floor Joists Considering Local Buckling Effects
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Date
2019-05
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Addis Ababa University
Abstract
This paper reports the local buckling effect on CFS section and an analysis and design program for composite timber CFS floor joist slab was developed. Cold formed steel structural members have enjoyed an increasing popularity over recent years. These sections offer various advantages over hot rolled steel sections such as, high strength-to –weight ratio, a straight forward and versatile manufacturing process. The local buckling effect on CFS sections was studied using numerical analysis on a finite element simulation software ABAQUS. Five tests were conducted to study the local buckling effect on channel CFS sections. Results show that all specimens but one had a failure stress less than the yield strength. Indicating that the specimens with web height ranging from 64 mm to 203 mm are class 4 and one of the specimens with web height of 40 mm is different from class 4 however, Eurocode 3 Part 1-3 treats all CFS sections as class 4 which leads to conservative and uneconomical design. The classification stated on Eurocode 3 Part 1-1 classifies the sections used as class 1 for web height ranging from 40 mm to 102 mm and the one with web height of 203 mm as class 3. This contradicts with the results obtained from ABAQUS. From this it can be concluded that this classification cannot be applied for CFS sections and since all CFS sections are not class 4 there should be a classification for CFS sections alone. Furthermore, the designing program gives out sufficient sections for the given slab size and the intended purpose of the slab. Results include sufficient timber section, CFS floor joist section from database with its spacing or checks if the user inserted section of timber and CFS are sufficient or not. If transversal beam is said to be needed by the user it gives out the sufficient IPE section. Last but not least the sufficient IPE section for main beam is also provided with their corresponding weights for economical and efficient design. Based on this study cold formed steel sections tend to buckle locally as the web height increases, so while using slender sections it is better to use stiffeners or other infill materials to prevent the section form buckling locally and the classification of sections in to classes should be given attention for efficient use of the sections.
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Cold formed steel (CFS), joists, oriented standard board (OSB), local buckling