Randnahe Kopfbolzen – Ermüdungsverhalten unter Querschub

Abstract

Kopfbolzen, die in neuen interessanten Konstruktionsformen nahe zum freien Bauteilrand des Betons angeordnet werden, zeigen ein anderes, durch frühe Spaltrissbildung bestimmtes Tragverhalten als die üblichen randfernen Kopfbolzen. Der effektive Randabstand hat einen bedeutenden Einfluss auf die Tragfähigkeit. Für die bisher schon in DIN EN 1994‐2, Anhang C gegebenen Bemessungsregeln bei einer randnahen Anordnung mit Beanspruchungsrichtung längs oder quer zum freien Bauteilrand werden Ergänzungen und Verbesserungen erläutert. Insbesondere werden Forschungsergebnisse zum Ermüdungsverhalten unter Querschub vorgestellt, die auch zu einer Bemessungsgleichung für die Ermüdungsfestigkeit von randnahen Kopfbolzen unter Querschub führen. Darüber hinaus wird für diesen Fall der Einfluss einer Ermüdungsbeanspruchung auf die statische Resttragfähigkeit näher betrachtet. Headed studs that cause splitting forces in direction of the slab thickness – Fatigue behaviour under transverse shear – enhancement of existing rules. Headed studs, arranged in interesting innovative composite cross sections near to the slab surface, show a different load carrying behaviour due to splitting forces than studs in standard situations without any edge influence. The effective edge distance has a significant influence on the carrying capacity. For the rules given in EN 1994‐2, Annex C for the case of headed studs close to the concrete surface with load direction either in longitudinal or transverse direction, enhancements and improvements are explained in detail. Especially research results on the fatigue behaviour of headed studs close to the concrete surface under transverse shear are introduced und a design equation for the fatigue resistance is provided. Furthermore the influence of a fatigue loading on the residual static resistance of headed stud arranged close to the concrete surface is discussed.

Experimental investigation of steel-concrete composite push-out tests with embedded corrugated web

“…Therefore, the current research program has the aim to study the structural behaviour of shear connectors having concrete dowels or horizontal headed studs for composite structures using experimental tests, also the impact of important parameters on load-bearing capacity, stiffness and failure mode. The parameters that have the greatest influence on shear strength are: the dimensions of the trapezoidal profile (plate width, inclination angle), embedding depth, concrete strength and the parameters of additional shear connectors (Kuhlmann and Raichle, 2011; Röhm, 2009; Raichle, 2015) and related design proposals can be found in (Kim et al, 2011; Novák and Röhm, 2009; Raichle and Kuhlmann, 2015). Accordingly, the research program focuses on examining these structural details.…”

“…There are additional conditions that have to be fulfilled and manually checked as follows: (a) the thickness of the concrete slab should be at least 250 mm and (b) the width of the concrete slab should be at least 900 mm. The exact determination of the coefficients can be found in (Raichle, 2015).…”

“…A total of 43 specimens having corrugated web were manufactured using embedded type shear connectors (Figure 3). The experimental specimens were designed based on numerical simulations and literature recommendations (Kuhlmann et al, 2011; Raichle, 2015; Röhm, 2009).…”

“…In 2010, Röhm and Novák (2010) tested the out-of-plane bending moment resistance of concrete dowels on an experimental basis. Röhm (2009) also developed a design formula for concrete dowels on embedded trapezoidal webs, while Raichle (2015) developed a design formula for horizontally placed headed studs on embedded trapezoidal webs. He et al (2018) performed an experimental program with finite element calculations for a connection of a hybrid structure with corrugated steel web and lower concrete slab.…”

Headed studs close to concrete edge under pull-out

“…However, there are still some aspects that require a further study, this is the case of the fatigue strength of the connection under vertical shear, corresponding to the fatigue loading derived from wheel loads. In this framework, a proposal of enhancement of the Annex C based on the works from [4], [13] has been implemented [14].…”