Schubverhalten von Biegebauteilen ohne Querkraftbewehrung

Abstract

Shear response of reinforced concrete members without stirrups under bendingThis contribution presents a new model to determine the shear capacity of reinforced concrete members under bending without shear reinforcement. The main idea of the model is the consideration of principal stress in the region of crack tips of the flexural cracks due to bending. A potential band for the formation of a critical shear crack that tends to connect the tips of existing flexural cracks can be assumed. The width of this band decreases with the increasing of the bending moment and gets larger when the shear force becomes higher. This means the bending moment affects positively the shear capacity. With the new model the shear capacity and the crack pattern in previous shear tests with different structural systems and loading conditions can be explained, which is generally not possible with the existing models.

Shear resistance of reinforced masonry beams with and without additional concrete or prestress

“…Consideration of a partial safety factor γ was omitted since the test values were to be explained by calculation in this case (9) with f(α) masonry strength depending on direction and loading angle α. In this case a calculation rule of the fib MC 2010 for the total shear resistance for unreinforced building elements was adapted for masonry.…”

“…Since either masonry with reinforcement or with prestressing tendons was used for all test samples, the longitudinal strain ε x can be determined with Eq. The effect of the additional layer was described regarding the increase of load-bearing capacity with a geometrical interaction between concrete and masonry in Equation (11). In contrast to the calculations for reinforced concrete building elements, the internal level arm for masonry z was assumed to be z = 0.85 × d. A comparison of the calculated shear forces resistances V rechn.…”

“…(5). (11) with h c height of the additional layer of concrete f cm average compressive strength of the additional layer of concrete. with experimentally obtained values V exp.…”

“…In contrast, masonry has inhomogeneous, anisotropic properties depending on factors such as the coring pattern and the bonding overlap of the masonry elements as well as the detailing of the head joints. The SMCFT model describes the behaviour of reinforced concrete elements under shear loading on the basis of the mechanical fundamentals of [11]. In response to this criticism, a new shear concept for RM beams is currently being worked on at the Ostwestfalen-Lippe University of Applied Sciences [10].…”

“…Z. an einem neuen Schubkonzept für Mw-Balken gearbeitet[10]. Das SMCFT-Modell beschreibt das Tragverhalten querkraftbeanspruchter Stahlbetonbauteile auf der Basis mechanischer Grundlagen von[11].Der vorliegende Beitrag enthält die Ergebnisse rechnerischer Überprüfungen mit im Experiment erhaltenen Querkraftwiderständen von schlaff bewehrten und vorgespannten Mw-Balken mit und ohne Ergänzungsschicht aus Beton. Es wird als "Simplified Modified Compression Field Theory" (SMCFT) bezeichnet, welches im Rahmen von[10] für Mauerwerk unter anderem materialspezifisch ergänzt wird.…”