Design against splitting failures in reinforced concrete due to concentrated forces and minimum bend diameter of reinforcement. (15th October 2021)

• Record Type: Journal Article
• Authors: Monney, Frédéric; Fernández Ruiz, Miguel; Muttoni, Aurelio
• Is Part Of: Engineering structures. Volume 245(2021)
• Publication Date: 2021-10-15
• Subjects: Reinforced concrete -- Mandrel diameter -- Concentrated forces -- Testing -- Detailing rules -- Spalling -- Splitting -- Fibre-optic measurements -- Digital image correlation; Structural engineering -- Periodicals; Structural analysis (Engineering) -- Periodicals; Construction, Technique de la -- Périodiques; Génie parasismique -- Périodiques; Pression du vent -- Périodiques; Earthquake engineering; Structural engineering; Wind-pressure; Periodicals; 624.105
• DOI: 10.1016/j.engstruct.2021.112902
• Languages: English
• ISSNs: 0141-0296

Abstract

Highlights: Comprehensive literature review including research and design codes on detailing of mandrel diameters. A test series on sixty-five specimens including loops and prisms with detailed measurements is presented. Out-of-plane displacements to understand spalling failures are investigated by using Digital Image Correlation. Consistent mechanical modelling assessing spalling strength. Innovative design recommendations. Abstract: Plastic bending of reinforcement bars against mandrels is the usual procedure to provide bends and hooks for steel reinforcement bars. Minimum mandrel diameters are usually given in to codes of practice, depending on the type of detail and diameter of the bar. These recommendations for the bend diameter ensure a safe transfer of forces, avoiding splitting failures that may potentially limit the resistance of the detail. In most cases, these recommendations are largely based on a number of experimental works performed several decades ago. At that time, these investigations were performed on reinforcement and concrete with lower strengths than currently used. This paper presents the results of a comprehensive research programme on bend detailing and required mandrel diameter to avoid local concrete failures leading to spalling of the concrete cover. The results of an experimental programme are presented, showing the influence of different parameters such as the mandrel diameter, the bending angle and the concrete cover. The tests were instrumented with advanced measurement techniques (fibre-optic measurements and digital image correlation), showing that consistent modelling of the transfer of forces can be performed on the basis of the geometrical and mechanical parameters of the details.