Effect of Residual Strength Parameters on FRC Flexural Creep: Multivariate Analysis

Abstract

This paper reports the multivariate analysis of experimental results from more than one hundred FRC prismatic specimens tested under sustained flexural loads for at least 90 days, collected from previously published sources. Principal Component Analysis was used to minimise the number of variables in the modelling process while compromising the minimum amount of information. The creep parameters analysed were the creep coefficients at 14, 30, and 90 days and the corresponding crack opening rates. They were related to the following factors: concrete compressive strength, residual load-bearing capacity in flexure, fibre material, and load. Multiple linear regression was used for the modelling of these relationships. Higher levels of flexural toughness were found to significantly reduce the variability of all creep parameters. Differences in fibre material were detected to introduce important differences in interaction with other factors, especially the load ratio, which was attributed to the association between the range of flexural toughness to be expected and the type of fibres used.

Improvements in test methodology and characterisation of long-term flexure behaviour of fibre-reinforced concrete

“…Fortunately, near 70% of creep tests were conducted in a climate room where either temperature of RH could be controlled. Nevertheless, it is clearly stated that temperature control is easier than RH since some creep tests [79,85,86,89,103,107] were reported in controlled temperature, but a considerable scatter in RH where it could be just restricted. Temperature is usually kept constant in values ranging from 19 to 25 ºC, being 20 ºC the most used temperature during the creep test.…”

“…This methodology was assessed on 7 FRC series [39,[77][78][79] comprising 39 prismatic tested on flexure creep. Long-term experimental results obtained using the presented methodology [77][78][79][80][81] are included in the state-of-the-art analysis carried out in Chapter 2.…”