Precast pipe bridge segment verification at Hungarian chemical plant
\[ \textsf{\textit{\footnotesize{Global 3D model of the structure in AxisVM}}}\]
About the Project
Located at a chemical plant in Hungary, the project focused on the assessment of an existing pipe bridge segment to verify its structural capacity under current operational loads. The pipe bridge extends over 100 meters, but due to its modular repetition, only a representative segment required detailed evaluation. The existing structure lacked design documentation, necessitating advanced surveying and diagnostic techniques to capture geometric and material data.
To reconstruct the as-built geometry, a 3D laser scan was performed, while reinforcement details were identified using a rebar scanner. Concrete strength was assessed via Schmidt hammer testing, and the quality of the reinforcing steel was estimated based on construction period norms, nearby structure documentation, and engineering experience.
\[ \textsf{\textit{\footnotesize{Vierendeel column modeled in Detail - Topology optimization}}}\]
Engineering Challenges
The structure comprises precast, prestressed reinforced concrete “T” beams resting on columns embedded into socket footings, supported by monolithic block foundations. One key design element is the centrally placed Vierendeel column, which provides longitudinal stability and resists horizontal forces generated by pipe movement or environmental loading. The remaining columns act as pinned supports, stabilized longitudinally by this fixed central element.
\[ \textsf{\textit{\footnotesize{Internal force diagrams in AxisVM}}}\]
In the transverse direction, both the fixed and pinned columns behave as cantilevers with fixed bases. In the longitudinal direction, pinned columns act as base-fixed with lateral support at the top, while the Vierendeel column was modeled either as a cantilever or as an oscillating vertical member between the beams.
Thermal expansion effects were negligible due to the mixed support configuration. The structure met requirements under transverse wind load, however, longitudinal horizontal forces posed a significant challenge. These induced shear transfer mechanisms within the beams, forces that could not be accurately captured using traditional bar-element finite element models.
\[ \textsf{\textit{\footnotesize{Results in Detail - Concrete stress, Reinforcement stress, Crack width, Deformation}}}\]
Solutions and Results
To address the limitations of conventional modeling, IDEA StatiCa Detail was employed to assess the complex shear behavior in the beams under longitudinal loading. The internal force envelope, derived from global analysis, revealed a governing load combination. These internal forces were applied in Detail to assess the detailing adequacy of the beams.
Given the significant depth of the connecting beam, a strut-and-tie model was considered more appropriate to reflect the internal force distribution. Manual calculation of such a model would have been prohibitively time-consuming and error-prone due to its complexity. Instead, IDEA StatiCa’s Topology Optimization tool was used to visualize the likely force paths. The generated topology confirmed the expected force flow, enabling the engineers to input the actual reinforcement layout for verification.
The results showed that, with the applied detailing, the load-bearing capacity of the fixed column was sufficient. Additional checks using IDEA StatiCa revealed notable differences in the deformations under load, which helped inform further evaluation of serviceability performance.
About BASE-Engineer Kft.
BASE-Engineer Kft., based in Pécs, Hungary, specializes in the structural design of large-scale industrial facilities as well as residential and commercial buildings. The firm combines traditional engineering experience with cutting-edge digital tools to deliver technically sound and constructible solutions. More information is available at base.hu.
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