Influence of specimen geometry on fracture toughnesses of concrete based on boundary effect model. (December 2021)

• Record Type: Journal Article
• Authors: Zhao, Yanhua; Yin, Nana; Xu, Bohan; Tao, Ye
• Is Part Of: Theoretical and applied fracture mechanics. Volume 116(2021)
• Publication Date: 2021-12
• Subjects: Fracture toughness -- Boundary effect model -- Three-point bending -- Compact tension -- Four-point bending; Fracture mechanics -- Periodicals; 620.1126
• DOI: 10.1016/j.tafmec.2021.103135
• Languages: English
• ISSNs: 0167-8442

Abstract

Highlights: A new approach to derive the initial fracture toughness based on boundary effect model is proposed. The specimen geometry has little influence on fracture toughnesses. Fracture toughnesses can be used to predict cracking initiation and maximum load. The ratio of two toughnesses varies slightly for different geometric shapes. Abstract: This paper presents the effect of specimen geometry on fracture characteristics of concrete in terms of fracture toughness K Ic and initial fracture toughness K Ic ini . Three commonly used specimen geometries in laboratory were adopted in the study, that is, three-point bending (TPB), compact tension (CT) and four-point bending (FPB) specimens. The Boundary Effect Model (BEM) was used to determine these two fracture parameters, where a new approach was proposed to derive K Ic ini . To do this, only the maximum aggregate size d max, the maximum load P max and the initial crack length relative to the specimen depth α 0 were required. Previous experiments from TPB, CT and FPB specimens were reutilized to acquire K Ic and K Ic ini, and then the geometry influence on these two fracture toughnesses were investigated. The results show that the gained values of K Ic and K Ic ini from TPB, CT, FPB separately or combined TPB + CT + FPB were rather close, meaning little influence from specimen geometry on fracture toughness. Additionally, the ratio of K Ic ini / K Ic was almost the same regardless of specimen geometry shape and α 0 when 0.2 ≤ α 0 ≤ 0.8.