A Stress-Strain Model for Unconfined Concrete in Compression considering the Size Effect

Abstract

In this study, a stress-strain model for unconfined concrete with the consideration of the size effect was proposed. The compressive strength model that is based on the function of specimen width and aspect ratio was used for determining the maximum stress. In addition, in stress-strain relationship, a strain at the maximum stress was formulated as a function of compressive strength considering the size effect using the nonlinear regression analysis of data records compiled from a wide variety of specimens. The descending branch after the maximum stress was formulated with the consideration of the effect of decreasing area of fracture energy with the increase in equivalent diameter and aspect ratio of the specimen in the compression damage zone (CDZ) model. The key parameter for the slope of the descending branch was formulated as a function of equivalent diameter and aspect ratio of the specimen, concrete density, and compressive strength of concrete. Consequently, a rational stress-strain model for unconfined concrete was proposed. This model reflects trends that the maximum stress and strain at the peak stress decrease and the slope of the descending branch increases, when the equivalent diameter and aspect ratio of the specimen increase. The proposed model agrees well with the test results, irrespective of the compressive strength of concrete, concrete type, equivalent diameter, and aspect ratio of the specimen.

Tensile Strength of Cement-Treated Champlain Sea Clay: An Experimental and Numerical Study

“…Its testing result proved to be aberrant. In general, the samples showed failure patterns in unconfined compression that are similar to that of concrete as documented by Yang et al (2019), indicating that the use of BTS and UPT, which are suitable for concrete materials, can be justified. were used by Liu, et al (2018).…”

Stress–strain model for FRP confined heat-damaged concrete columns

“…For the case of AC columns, the experimental and analytical studies conducted by Refs. [33][34][35][36][37][38] evidenced that ε c0 increases with the concrete compressive strength (f c0 ). Jansen and Shah [34] experimentally demonstrated that the column aspect ratio (λ L as the ratio of the column height to its diameter) has also considerable influence on ε c0 due to the occurrence of strain-localization within a finite zone with a pronounced gradient of deformations due to the concrete post-peak strain-softening behavior.…”

“…In this study, in order to estimate ε c0 , a large database (Table 3) was compiled from the experimental results available in the literature, resulting in 604 unconfined concrete specimens (AC) with a broad range of concrete properties and geometry configurations. Note that for the case of non-circular columns with a total cross-section area of A g , based on Yang et al [38] recommendations, λ L can be determined as L/d eq where L is the columns' height and d eq is the equivalent circular ]). Based on a preliminary sensitivity analysis, a low effect was achieved for the influence of the column size (i.e.…”

Analytical model to predict axial stress-strain behavior of heat-damaged unreinforced concrete columns wrapped by FRP jacket

“…As a result, by calculating f ctr,T , ε ctr,T , f cu,T and ε cu,T using Eqs. (35), 34,21,30), the information of the key components of the proposed stress-strain model can be addressed.…”