Shear strength of slender SCC beams - possible differences from VC beams

Abstract

ResumoIn comparison with vibrated concrete (VC) of the same strength class, self-compacting concrete (SCC) typically has a lower coarse aggregate content and, eventually, a smaller maximum aggregate size. This may reduce the aggregate interlock between the fracture surfaces in SCC. Since the aggregate interlock plays an important role in the shear strength of slender beams, SCC beams may have a shear strength lower than that of similar VC beams. This article summarizes experimental studies on the shear strength of reinforced SCC slender beams without and with shear reinforcement. The shear strengths of SCC beams are compared with the ones of VC beams and also to the calculated ones according to different code procedures. It is shown that powder-type SCC beams tend to have lower shear strength than similar VC beams and that the difference depends upon the concretes composition and the characteristics of the beams.Keywords: self-compacting concrete, slender beams, shear strength.Em comparação com o concreto vibrado (CV) de mesma classe de resistência, o concreto autoadensável (CAA) tipicamente apresenta menor quantidade de agregado graúdo e, eventualmente, menor dimensão máxima deste agregado. Isto pode reduzir o engrenamento de agregados entre as superfícies de ruptura do CAA. Sendo o engrenamento dos agregados um parâmetro de influência importante na resistência à força cortante de vigas esbeltas, as vigas de CAA podem ter resistência à força cortante menor que a de vigas similares de CV. Este artigo resume estudos experimentais sobre a resistência à força cortante de vigas esbeltas de CAA sem e com armadura de cisalhamento. As resistências à força cortante de vigas de CAA são comparadas com as de vigas de CV e também com as calculadas segundo procedimentos de diferentes normas. É mostrado que as vigas de CAA com menor teor de agregados graúdos tendem a ter menor resistência à força cortante que vigas semelhantes de CV e que a diferença depende da composição dos concretos e das características das vigas.Palavras-chave: concreto autoadensável, vigas esbeltas, resistência à força cortante.

Shear Performance of Concrete Beams with a Maximum Size of Recycled Concrete Aggregate

“…Capacity. e ultimate shear strength of slender beams without shear stirrups mainly depended on the concrete compressive strength and aggregate interlock between cracked surfaces [27]. Aggregate interlock is associated with type, and the maximum size is the greatest contributor to concrete shear capacity for beams without transverse shear reinforcement according to Fenwick and Pauley [51] as cited by Zhang et al [26].…”

“…Yi et al [18] concluded that for normal concrete, the maximum aggregate size has a minimal effect on the concrete tensile strength, however, the shear capacity of beams without shear stirrups is improved with an increase in aggregate size. For normal concrete, the ITZ is the weakest link [15,[19][20][21][22][23][24][25][26] in the concrete matrix, and it is essentially determined by the maximum size of the coarse aggregate [27]. e bigger the size of aggregate, the higher the shear resistance offered by aggregate interlock [27].…”

“…For normal concrete, the ITZ is the weakest link [15,[19][20][21][22][23][24][25][26] in the concrete matrix, and it is essentially determined by the maximum size of the coarse aggregate [27]. e bigger the size of aggregate, the higher the shear resistance offered by aggregate interlock [27].…”

Verification of selected calculation methods regarding shear strength in beams without web reinforcement

“…Over the years much research and many debates have taken place all around the world to better understand the shear mechanism in beams both with and without web reinforcement [1,2]. Although many experiments and analysis have been carried out, the provisions regarding calculating shear strength provide results that often differ from experimental data [3,4,5]. As it was prior proved by the Authors in the context of reinforced and prestressed concrete beams with shear reinforcement [6], the understanding of stress distribution in the support zone is still to be improved.…”