Žeželj’s bridge and critical load due building long arch

Abstract

This paper shows the influence of critical loads on the long-span arch of Žeželj bridge (ŽB) in Novi Sad. The construction of scaffolding for large-span concrete arches before the Žeželj‘s Bridge in Novi Sad was very expensive. That is why Žeželj envisioned the construction of RC arches in three longitudinal parts. But due to the rheological properties of concrete, primarily due to the influence of creep, and to a lesser extent shrinkage, the arches were temporarily interrupted at the top, i.e. dilation was left at the top of the arches. Since the arches were also longitudinally segmented in stages, the scaffolding was designed for only about 40% of the load, which significantly reduced the cost of the scaffolding of the large arch.

Namely, originally the arch was smaller, but due to the conditions of the Danube Commission regarding the width of the free waterway, the span of the large arch was increased to 211 m, whereupon a precast RC scaffold was constructed (for the first time in the world), using the cantilever method. According to Boško Petrović’s lectures (held during the period of 1991-2004 in NS): the critical moment during the construction of the bridge was the phase of introducing pressure forces into the semi-arches and specifically the moment of lifting the structure from the formwork-scaffolding.

The analysis of the influence in the arches during the construction phases was conducted in the Tower Radimpex. It is assumed that the old calculation was done in two ways, via the chain polygon of forces and tabularly by dividing one half of the arc into 10 to 20 parts. Because of symmetry, it was enough to analyse half of the arch.