Tests up to failure of a reinforced concrete Hennebique T-beam

Abstract

Reinforced concrete constructions of the first generation (pre-1914) form part of our heritage and therefore should be preserved for future generations. Few experimental studies have been conducted on Hennebique continuous structures to estimate the actual bearing capacity of this reinforced concrete system, which was the most popular in many European countries at the turn of the twentieth century. Important information is therefore often missing for accurate modelling of the behaviour of the structure, although structural assessment is crucial in the reuse of any construction. This paper presents results from three bending tests up to failure, carried out on beams from a narrow-gauge railway viaduct designed by Hennebique and built in Belgium in 1904. They provide better understanding of the mechanisms of failure and reveal the main strengths and weaknesses of the typical Hennebique T-beam. The overlapping length of the rebars at the supports is found to be the crucial aspect, even if a large capacity of ductility is observed. Failure occurred owing to slipping of the upper rebars above the support area. This means that attention should be given to detailing. Consequently, localised structural strengthening with additional reinforcements is probably required when seeking to enhance the lifetime of these old reinforced concrete structures.

Anchorage of Reinforcement Bars in Hennebique R.C. Structures

“…The intrinsic weaknesses of the early reinforced concrete structures, among which the Hennebique system plays the major role, is well known and addressed by several authors [4,[17][18][19][20][21][22]. The two main issues need specific attention: i) concrete compressive strength, affecting the bending capacity of the beams; ii) shear capacity, which depends on the amount of shear reinforcement and on the efficiency of its anchorage.…”

“…Brencich, M. Nebiacolombo 2 Nowadays warehouses, industrial facilities, a large number of bridges and buildings, either residential and public, built according to the Hennebique system, are in service. For many of them retrofitting is needed due to several reasons, such as material degradation, re-functioning and, mainly for strategic buildings such as schools, hospitals and public offices, for their seismic upgrade.The intrinsic weaknesses of the early reinforced concrete structures, among which the Hennebique system plays the major role, is well known and addressed by several authors [4,[17][18][19][20][21][22]. The two main issues need specific attention: i) concrete compressive strength, affecting the bending capacity of the beams; ii) shear capacity, which depends on the amount of shear reinforcement and on the efficiency of its anchorage.This paper addresses a specific problem: the anchorage performance of either bending and shear reinforcing bars.…”

Early Concrete Structures and Post-Patented Systems: Lessons to Preserve Early 20th Historical Heritage

“…It should be focused on the targets for mechanical strength in compliance with the regulations at that time, especially in early RC structures, and durability of the concrete. Studies on structures built following patented systems are frequent [10][11][12][13][14][15][16][17][18][19], although structures built in the post-patent period are now becoming an interesting period of study too [20][21][22][23][24][25][26].…”