Title: Closed loop control in crushing test for fibre reinforced concrete pipes

Author(s): Monte, R.; de la Fuente Antequera, A.; Dominigues de Figueiredo, A.

Publication: Symposium Paper

Volume: 343

Issue:

Appears on pages(s): 282-291

Keywords: Fibre reinforced concrete. Concrete pipes. Crushing test. Closed-loop control.

DOI:

Date: 10/1/2020

Abstract:
The mechanical behaviour of fibre reinforced concrete pipes (FRCP) is usually verified through three-edge bearing test (TEBT). More recent studies propose a design approach according to the fib Model Code 2010, involving the evaluation of mechanical behaviour in both service (SLS) and ultimate (ULS) limit states. The challenge consists in assessing with the proper accuracy and reliability the mechanical parameters by means of the TEBT method. This is generally performed using a hydraulic equipment with load control and without using devices to measure the diametric displacement. In this research program, TEBT was carried out using three different control systems. Two closed-loop controls, using pipe diametric displacement or actuator displacement, and an open-loop control by loading rate. The crack width development was also measured simultaneously with the diametric displacement, only for closed-loop control. An increase in the post-crack strength of the FRCP were observed when the closed-loop system was used. The results show significant differences between the mechanical performances of pipes tested in open or closed-loop control. Conversely, closedloop tests performed with actuator displacement control or pipe diametric displacement control show no significant differences. Crack opening measurement allows establishing a linear correlation with diametric displacement, this permitting to establish the values corresponding to the SLS and ULS deformation and respective loads. Consequently, the connection with the Model Code approach becomes possible as well as the design optimization of the FRCP.