215 Type: Arched bridge Location: Schaarbeek, Belgium (L36N between Brussels-North and Diegem) Owner: Infrabel, Belgium Architect: Tuc Rail, Belgium Erection Engineering: Ingenieursbureau STENDESS N.V., Lovendegem, Belgium Check of the bridge during erection Contractor: Victor Buyck Steel Construction N.V., Eeklo, Belgium Total steel weight: ± 1.650 tons Total length: 136 m Building period: 2005 Short description of the project It concerns the launching of a new bridge for the use of HST (High Speed Train) traffic at Schaarbeek, Brussels. The new bridge is an arched bridge with an orthotropic deck. The arches are built-up box girders. The main beams are built-up I-sections underneath the orthotropic deck. In order to reduce the disturbance of the train traffic under the bridge, the new arched bridge was erected on a newly build concrete bridge. On this concrete bridge the new arched bridge was built together and prepared for launching. Between the existing train tracks erection towers with skids were built to support the new bridge during launching. The positions of these erection towers were very non symmetrical because of the high density of tracks below. This caused an extra difficulty in the engineering study of the bridge launching. Ingenieursbureau Stendess N.V. was asked to check the new bridge during launching and to calculate and propose solutions for a safe launching. Several options were calculated and discussed with Victor Buyck Steel Construction. Challenges like global and local reinforcement of the main beam and launching with a launching nose lengths from 10 to 30 m, were investigated and judged. The solution with a launching nose of 30 m long was chosen. Because of the risk of buckling the buckling length of the bridge, diagonals were reduced by placing a horizontal lattice girder. During the launching, the reactions and the deformations of the bridge and launching nose were constantly compared with the calculated values in order to secure a safe launching. The launching itself was done smoothly and within 7 hours the bridge was in place. Use of ESA-Prima Win and SCIA•ESA PT Description of technical questions to be solved with ESA-Prima Win The complete 3D-model was formed with bars, the orthotropic deck plate was put together as 2D-elements. To realize a realistic behaviour of the bridge it was necessary to calculate and correct the effective width of the upper flange of the main beams along the whole bridge length and this for each launching phase. The effective widths were calculated according EC3 and based upon the M-lines in the main beam obtained by ESA-Prima Win. The corrections of the effective width could be easily done by the “rib” module in ESA-Prima Win. To avoid overload of the concrete bridge on which the launching started and on the erection towers it was necessary to perform constantly corrections with regard to altitude, real precision work. The input in EPW and obtaining the results of these altitude corrections out of ESA-Prima Win went smoothly. The check of the local impact of the reactions into bridge was done based on EC3 with the use of the results given by ESA-Prima Win. The altitude corrections, the reactions on the erection towers and the deformation of the launching nose were calculated for each launching phase. The results obtained from ESA-Prima Win could easily be put in table and graphics in order to obtain a document in which theory and praxis during the launching could be compared and a safe launching was possible. Description of our experience with Esa-Prima Win when realizing the project • Checking the structure as a combined model with 1D-2D-3D elements and with a high hyperstatic degree according EC 3. • The possibility of building up a flexible model to simulate the different altitude correction on the erection towers. • The possibility of changing the effective width of the orthotropic deck along the bridge length. • The short calculation time for the model pro launching phase and the easy and fast way to do a global check according EC 3. This was very important because of the high number of launching phases to be considered. Used modules • Base • 3D frame • 3D shell • Steel code check (EC3) Launching of arched bridge LN36 Schaarbeek, Belgium
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