73 Project: Bridge ‘Olsene’ across the ‘ Leie’ river Type: Arched bridge (Bowstring) Location: River “de Leie”, Dentergem (Oeselgem), Belgium Owner: Ministerie van de Vlaamse Gemeenschap - Afdeling Wegen en Verkeer West-Vlaanderen Architect: Ministerie van de Vlaamse Gemeenschap - Afdeling metaalstructuren, Brussels, Belgium Engineering office: Ingenieursbureau Stendess N.V., Lovendegem, Belgium Contractor: Steel: Victor Buyck Steel Construction N.V., Eeklo, Belgium - Concrete: Depret N.V., Zeebrugge, Belgium Total steel weight: ± 1.000 tons Total length: 112 m; Span: 110 m Highest point: ± 20 m (top of arches) Building period: 2005-2006 Short description of the project The existing concrete bridge had to be replaced by a new bridge and this for two reasons. Firstly, the stability of the existing bridge was no longer guaranteed for the increased traffic intensity. Secondly, the free passing under the existing bridge was limited in height and width and too small for the current ships to pass. The new bridge is a steel bridge with a span of 110 m, consisting of 2 drive lanes of 4 m and 2 lanes for pedestrians of 2,5 m. The bridge is an arched bridge (bowstring) with inclined arches of which the cross sections vary as well in height as in width along the bridge span. For the bridge deck an orthotropic steel deck with longitudinal trapezoidal stiffeners was chosen. The bridge is different from a classic bowstring bridge because the suspensions of the deck at the arch are not connected to the main deck beams. The suspensions are connected at the transverse beams, which support the main deck beams. The whole bridge was completely preassembled in the workshop, so that the assembly on the spot could be done smoothly. The erection, which was studied by Victor Buyck Steel Construction, was done using a ponton to support the bridge deck temporarily. In this work of art the great characters of steel came clearly to their right: the slim line and the playful form of the construction, speed of assembly and the possibility to combine heavy duty loads with an architectural design. Use of ESA-Prima Win and SCIA•ESA PT Description of technical questions to be solved with ESA-Prima Win and SCIA•ESA PT As well for the dimensioning of the steel bridge as for the dimensioning of the foundations (group of piles) ESA-Prima Win and SCIA•ESA PT were used. The complete 3D-model was formed with bars; the orthographic deck was put together as 2D-elements, with the purpose of creating the real vertical and lateral stiffness of the bridge. The tension bars, which support the deck, were simulated as classic bars. To simulate the horizontal (longitudinal) stiffness of the bridge supports, a 3D-model was made in which the 3D-bridge structure and the foundations (group of piles) were combined. For the calculations with regard to the traffic situation, each bridge member was given a buckling factor based on the rules of EC3. The beam check was then made by EC3 steel check of ESA-Prima Win. The buckling control of the arches was done in three ways. The first method with EC3-steel check of ESA-Prima Win, the second method was based on the calculation of the axial critical buckling force according EC3, the third method used the stability check and the second order calculation based on EC 3 of ESA-Prima Win. The second order calculation was done with SCIA•ESA PT. SCIA•ESA PT gives the possibility of a second order calculation with a predeformation based on a stability calculation for a 3D-model with bars and plates. Here SCIA•ESA PT really proved its progress compared to ESA-Prima win. In the calculation of this project the use of ESA-Prima Win was very intense and diverse: • Combination of 1D-elements and 2D-elements in one 3D-model. • Combination of different materials in one model (steel bridge – concrete pile foundation) • Stability control / critical buckling factor • Second order calculation based on predeformations from stability calculations and on EC. • Use of graphical sections • Use of cross sections with variable height • Rib calculations • Free loads on 2D-model (orthotropic deck) Description of our experience with ESA-Prima Win and SCIA•ESA PT when realizing the project. The challenge in the calculations of the project was found in the different aspects of steel calculation and in the design of an architectural bridge for heavy loads. For this ESA-Prima Win and SCIA•ESA PT were the most suited software because of the variety of possibilities to check the structure to the limit, based on linear calculations, EC 3 steel check control, stability control and second order calculation in one software program. This could be done in a user friendly and structured software environment. Used modules: • Base • 3D frame • 3D shell • Stability frame • Second order calculation • Steel code check (EC3) • Rib calculation • Graphical sections • Cross sections with variable height Bridge ‘Olsene’ across the ‘Leie’ river
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