*4.1. Introduction*

In this research, the Autodesk Robot Structural Analysis Professional 2015 program was used to determine the static and dynamic performance of structural systems and analyse the linearity and non-linearity of the system behaviour. This is a program for calculation by finite element structures that includes a wide range of design codes of all types of metal and concrete structures, with the possibility of contemplating other structural materials [24].

For different structures, the beam element is a slender structural member that offers resistance to forces and bending under applied loads [25]. It is represented by line elements used to create a 1D idealization of a 3D structure, and is computationally more efficient than solids or shells [18].

The use of a beam element is highly applicable to most beam structures, e.g., bridges, roadways, building constructions, and people movers (railcars, trams and buses), since they support linear and nonlinear analyses, including plasticity, large deformations, and nonlinear collapse [26]. It is easy to use especially when:


Thus, to reproduce the accident, the structure was modelled using beam elements. All combinations were performed using the European section database (EURO code). The geometry was defined in Autocad and then exported to Robot, where the boundary conditions were set. Herein, fixed supports are assigned to the two pillars of the 6 support structures (Figure 3). The transfer of forces, induced by the pipeline and the fluid to the support, are made by intermediate connectors welded to the steel beam tube.

**Figure 3.** Pipeline geometry defined in Robot structural analysis.
