Tension versus flexure: Reasons to modify the formulation of MC 2010 for cracking

Abstract

This paper critically evaluates the cracking model of MC 2010 with a view to the drafting of MC 2020. It emphasizes that there are differences in cracking behavior in tension and bending, which are not adequately recognized in the current model. Based on the analysis of experimental evidence, it shows that the current model has a significant skew in prediction performance when tension and flexure tests are considered separately. Based on these observations, modifications are proposed to account for the variation of tensile stresses

Calculation of maximum crack width for practical design of reinforced concrete

“…The proposed solution was validated by comparison of computational results with experimental observations from the literature, in particular from References 6, 7, 10, 17, 19, 29‐32, 44‐49. In contrast to the usual approach of assessing selected studies, the herewith aimed validation was made upon a rather broad database containing results of different studies with different conditions.…”

“…In this model understanding, A c,eff represents the spreading of the bond force from the reinforcement location into the member, whereby new macroscopic cracks are always formed as soon as the cracking force of the effective area is built up by bond action. The determination of A c,eff according to MC2010 33 and EC2‐1 37 is suitable for this purpose while other definitions depending predominantly on the diameter of the reinforcement, as proposed in References 51, are not permissible. Although it is of little importance for practical application, but for scientific work the application requirement of h /6 > d 1 should be fulfilled before using h c,eff = ( h − x )/3 for flexural members, as illustrated in Figure 8.…”

Rissbreitennachweis und Mindestbewehrung nach EC 2 – aktuelles Modell versus Vorschlag für die Revision

“…Bei der Definition von A c,eff im neuen Vorschlag wird zunächst in Anlehnung an den Vorschlag in [17] von der Wirkungszone eines Einzelstabs ausgegangen, wobei diese als Quadrat mit einer Kantenlänge des Zehnfachen des Stabdurchmessers f festgelegt wird. Ist der Stababstand größer als 10 f, so muss bei der Berechnung ein für sich wirkender Einzelstab betrachtet werden ("isolated bar" mit A c,eff = h c,eff • 10 f).…”

“…Bedeutung ist. Nachdenklich stimmt an dieser Stelle, dass die Versuche in [33] auch in die Kalibrierung von [17] eingeflossen sind, und nach letztem Informationsstand ohne zwischen guten und schlechten Verbundbedingungen zu unterscheiden.…”

“…B. gen, die sich mit der statistischen Auswertung von alten und neuen Versuchen mit Variation verschiedener Randbedingungen beschäftigen, vgl. u. a [14][15][16][17]…”