Isarsteg Nord near Freising, Germany
The bridge structure of Isarsteg as integrating artwork fits perfectly into the surrounding landscape. Taking nature as an example, the bridge spans the Isar river like a branched limb. Together, the ramps, stairs, columns, and horizontal beams represent the spatial framework. The pedestrian and cycle bridge, in total 525 ft long, was made of weather-resistant structural steel, S355 J2G2W (corten steel).
City of Freising, Building Division of the Municipal Administration for Road and Bridge Construction
|Project Management, Structural Analysis||
Bergmeister Ingenieure GmbH
Arch. Christoph Mayr, J2M Architekten
Dr.-Ing. Josef Taferner, Bergmeister Ingenieure GmbH
Dr.-Ing. Oliver Englhardt, &structures
Dipl.-Ing. Matthias Gander und Dipl.-Ing. Philipp Prighel,
Bergmeister Ingenieure GmbH
Prof. Antonio Capsoni, B&C Associati
The engineering office Bergmeister Ingenieure used the RFEM and SHAPE-THIN programs for the structural analysis of the 3D structure.
The structural design of the bridge was carried out in a sustainable manner. The slim bridge is a rigid, statically indeterminate frame structure. All components, including the foundation and the abutment, are rigidly connected to each other.
The maximum span of the bridge amounts to 180 ft and the width to 12.30 ft. The superstructure, the columns, and the stairs consist of keel-shaped, torsional rigid box sections.
The bridge deck consists of a reinforced concrete flange with a thickness of 5.9 in and a concrete quality of C35/45. It is rigidly connected to the cover plate t = 0.98 in of the steel box section by welded studs. The studs have a distance of 1.64 ft in the transverse direction and 1.97 ft in the longitudinal direction.
The bridge has been cambered by the deformation components from the self-weight. Under the maximum variable load, the structure deforms by about 4.4 in, which corresponds to l/504. The dynamic analysis resulted in a natural frequency of 1.33 Hz for the first mode shape. To ensure user comfort, a vibration damper was arranged.
The aesthetic structure of the Isarsteg received the German Steel Construction Award in 2016 and second place in the Engineering Prize of the Bavarian Chamber of Engineers in 2017. Moreover, it received a nomination for the German Bridge Engineering Award in 2018.
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The effects due to snow load are described in the American standard ASCE/SEI 7-16 and in Eurocode 1, Parts 1 through 3. These standards are implemented in the new RFEM 6 program and the Snow Load Wizard, which serves to facilitate the application of snow loads. In addition to this, the most recent generation of the program allows the construction site to be specified on a digital map, thus allowing the snow load zone to be imported automatically. These data are, in turn, used by the Load Wizard to simulate the effects due to the snow load.
For the components of the joint, you can check whether stability failure is relevant (add-on structural stability for RFEM 6/RSTAB 9 required).
The critical load factor for all analyzed load combinations and the selected number of mode shapes is calculated for the connection model. The smallest critical load factor is compared with the limit value 15 from the standard EN 1993-1-1, clause 5. In addition, a user-defined adjustment of the limit value is possible. Furthermore, the corresponding mode shapes are displayed graphically as the result of the stability analysis.
For the stability analysis, an adapted surface model is used to specifically recognize the local buckling shapes. The model of the stability analysis, including the results, can also be saved and used as a separate model file.
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Programs Used for Structural Analysis
Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids, and contact elements
Design of reinforced concrete members and surfaces (plates, walls, planar structures, shells)
Stress analysis of steel surfaces and members
Dynamic analysis of natural frequencies and mode shapes of member, surface, and solid models
Stability analysis according to the eigenvalue method
Consideration of construction stages during a building phase