Location and name of the bridge
Name of the bridge: "Margit" bridge
Distance: 1648+750 km
Country: Hungary
City/town: Budapest
Year of building - completion: 1872 - 1876.
wing bridge to the island: 1899 - 1900.
Year of widening - completion: 1935 - 1937.
Year of rebuilding - completion: 1946 - 1948.
Year of reconstruction: 1978 - 1979.
Span lengths: 73.5 + 82.67 + 2 * 87.88 + 82.67 + 73.5 m
Roadway widths: 3.5 + 18.0 + 3.5 m
Designer: MÁVAG, Emil 0rmás
Main contractor: MÁVAG
Rebuilding cost: 97 million HUF (1948)

Traffic function of the bridge
Highway bridge carrying 2 tramway tracks and 4 traffic lanes

Antecedents; the history of the bridge
The construction of the bridge was ordered by the Parliament under law No X. in 1870. On the basis of this law tenders were invited internationally. Six of the 43 plans were examined in details by the jury. The first prize was offered to the plan of a French engineer, Ernest Gouin, and it was accepted, as the basis of construction.
As that time the Danube was divided there to two arms of different widths by the Margaret Island, the first prize winner plan contained two spans in the narrower and three spans in the wider arms. As not much later the regulation plan of the Danube was modified, before the beginning of construction, the number and lengths of the spans were changed and the bridge became symmetric to its axis, to the Margaret Island.
The construction itself was started immediately and it was carried out by Societe de Construction de Batignoles, by the company of the first prize winner designer between 1872 and 1876. The wing bridge to the Margaret Island was built later, as the island was privately own before; now it shows more or less the original form of structure.
The river bridge is a six span deck-type construction, with the speciality, that between the axes of the two symmetric halves of the bridge there is a 30* angle at the Margaret Island.
This bridge became a very frequently used one in the city and its width was narrow for the increasing needs of traffic. Its widening was carried out in the 30's. The width was increased by enlargement of the piers and by constructing two new arches in all of the spans to the south direction.
During World War II, the complete bridge was blown up. The East three span in November 1944, while the West three ones in January 1945.
First a timber provisional bridge was built, but it was destroyed by the ice-flow in 1946, later a pontoon bridge was built, having the nickname "Manci" bridge.
Instead of the eight arches in each span of the destroyed bridge, six new ones were applied during rebuilding. The approach spans on the two banks and the floor system were badly corroded after a working period of 30 years, and these parts had to be replaced by new structures.

The technical data of the bridge

Structural system, span lengths, widths
The main girders of the rebuilt bridge are simple supported arches of constant height. The loading from the deck is transferred to the arches by slender pillars. The shape of the arches differs from the original ones, their supports were lowered and the height of the arches was increased. The main connections are riveted ones, the floor system is welded.

Method of construction/erection; joints
The arches were preassembled in two halves, they were taken to their final position by a floating crane of 100 t capacity and the middle riveted connection was made in site.

Test loading(s); periodical assessment of serviceability
The main reconstruction work of the Danube bridges in Budapest started in 1974 and the first one in these series was the Margit bridge.
At that time the approach span of 20.66 m length on the Pest side was original. This bridge part was one of the oldest steel bridges, which was manufactured by Hungarian firm from home produced puddled steel. There were twelve parallel main arches and they, together with the floor system and double diagonals and verticals, formed a structure of statically multiply undetermined.
One part of the measurement program included load test on this structure, to determine the real behaviour and to compare them to different analytical results.
Although three different analytical models have been calculated, none of them were in good and consequent correlation to the measured nature of deflections and stresses.
Each span of the river bridge contains seven hinged arches and they support the floor system through verticals. The aim of the loading tests in this case was to determine the actual cross distribution of the live load among the main arches. The deflection measurement results showed that for a given load position the distribution is different in distinct cross sections. If the loading was positioned around the first quarter of the span and one half of the width, in the third quarter of the span the deflection distribution was more or less uniform, while in the loaded section there were remarkable deviations from that.

Literature
Sávos, K.: Épül a Margit-hid, Általános Mérnök, 1947. No.7.
Korányi, I. - Szittner, A.: Ellenőrző vizsgálatok a Margit-hidon, Mélyépitéstudományi Szemle, 1976. No.4.
Csölle, E. - Kozma, K.: A Margit-hid felujitása, Mélyépitéstudományi Szemle, 1979. No.8