Redistribution effects in linear elastic analyses of continuous composite steel-concrete beams according to Eurocode 4

Abstract

Different analytical methods, with different levels of approximations and accuracy, are available for analysis of continuous composite steel-concrete beams. The Eurocode 4 recommends few simple methods for calculation of creep, shrinkage, cracking of concrete and shear lag effects that are explained in the paper. Through the numerical examples of four continuous composite steel-concrete beams, the proposed methods of analyses are evaluated and compared. Practical recommendations for analysis of this type of girders are formulated

Part I: Modified Buckling Factor for Columns in Braced and Unbraced Frames with Composite Girders

“…Nowadays, steel-concrete composite structures are commonly employed in the construction of buildings [17][18] [19] and have a large market share in numerous countries [20] [21].Actually, the reasons for this are based on a variety of advantages that may be achieved by combining two distinct materials into a single component: Significantly increased span width-to-height ratio, high load capacity, high rigidity, lower dead weight, fast construction process, superior structural safety at a reasonable cost, and acceptable fire performance [17] [18] [19].…”

“…There have been a number of studies dedicated to developing models for evaluating composite beam behavior, the majority of which concentrated on beams with positive bending moments. A few studies focused on the ultimate bearing capacity of composite beams under hogging moment and the crack growth in concrete slabs [17] [23]. It's crucial to understand how composite beams behave structurally under negative moments.…”

“…Furthermore, nonlinear analysis as well as computer software are essential for the study of composite structures since they are so complicated. Even so, modern design standards like Eurocode 4 (EC4) use linear-elastic analysis with some changes to account for current nonlinearities and make design simpler [17]. When the extreme-fiber tensile stress in concrete reaches twice the mean value of the axial tensile strength specified by EN 1992-1-1 [25], concrete cracking decreases flexural stiffness in hogging moment zones but not in sagging regions.…”

“…Composite girders are regarded fully connected [28]. As a result, the zone of cracked concrete estimated by "cracked" analysis was significantly less than the length expected in 15% cracked analysis [17].…”