Concrete compressive strength: From material characterization to a structural value

Abstract

The compressive resistance of concrete in new structures is usually characterized on the basis of tests performed on concrete cylinders or cubes under relatively rapid loading conditions. Although efficient for material characterization, these tests do not acknowledge a number of phenomena potentially influencing the compressive resistance of concrete in actual structures. For this reason, when performing a structural analysis, strength reduction factors are usually considered in codes of practice modifying the uniaxial strength of material tests. In this paper, a detailed investigation of the influence of material brittleness and internal stress redistributions on the structural response of reinforced concrete members is presented. This work is based on a number of theoretical considerations and supported by the experimental results of more than 400 reinforced concrete columns tested with or without eccentricity and gathered from the literature. The results show the pertinence of considering a brittleness factor in the calculation of the structural resistance of reinforced concrete columns and compression zones of beams. The results of this work are eventually formulated in terms of code‐like proposals, currently considered in the draft of the new Eurocode 2 (prEN 1992‐1‐1:2018).

Compressive strength of core specimens drilled from concrete test cylinders

“…It can be seen from Figure 9 that the compressive strength increased in most test specimens from the casting surface to the bottom. This finding is in agreement with the findings of Moccia et al (2020) 50 . A similar phenomenon is also seen in density results in Figure 9, but with the difference that the cores taken closest to the casting surface in many cases have a higher density than the next core below.…”

An intelligent nanomesh-reinforced graphene pressure sensor with an ultra large linear range

“…Inspired by the commonly used reinforced concrete structure, whose mechanical properties can greatly improve the compressive strength of concrete, [30][31][32][33][34] we herein propose and fabricate a nanomesh-reinforced graphene pressure sensor (NRGPS) based on the PU nanomesh and laser scribed graphene (LSG). The PU nanomesh can be regarded as the skeleton of reduced graphene, which is similar to the steel bars in reinforced concrete.…”

Frühzeitiges Versagen bei hochfesten Stahlbetonstützen mit großen Stabdurchmessern

“…Aufgrund der Querdehnungsbehinderung des Betonkerns entstehen angrenzend an die Bügelbewehrung Querzugspannungen, welche lokal die Betondruckfestigkeit in der Betondeckung abmindern [21–23]. Matz und Empelmann begründen in [24] die Entstehung der horizontalen Querzugspannungen aufgrund der Umlenkung der Längsdruckspannungen im Bereich der Querbewehrung.…”

“…Je größer die Umschnürungsbewehrung, desto früher entsteht diese Versagensfläche bezogen auf die Querschnittstragfähigkeit. Da die Rissfläche nicht allein für ein Ablösen der Betondeckung vom Kernquerschnitt verantwortlich sein kann, wurden weitere Gründe präsentiert, die zusätzlich auftreten.Aufgrund der Querdehnungsbehinderung des Betonkerns entstehen angrenzend an die Bügelbewehrung Querzugspannungen, welche lokal die Betondruckfestigkeit in der Betondeckung abmindern[21][22][23]. Matz und Empelmann begründen in[24] die Entstehung der horizontalen Querzugspannungen aufgrund der Umlenkung der Längsdruckspannungen im Bereich der Querbewehrung.…”