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November 2005 

<printable version>

Dear eNews reader,

Currently there is a lot going on in the construction world and through this eNews we like to fill you in on various topics. As always, our regular items inform you about the latest state of technology, the developments on the market and striking projects. We gladly invite you to one of the many events SCIA organises or in which we participate.

Here are the items for this month:

With Allplan 2005.1 Nemetschek and SCIA have released various new modules.

The BIM concept has really given shape to in the new module for modelling steel constructions. With the parametric templates in Allplan it is possible to model and modify steel constructions, including connections. It is also possible to use the powerful 3D modeller of SCIA.ESA PT within the Allplan environment. As is customary in Allplan, steel objects and all other elements, such as concrete beams, brickwork walls, stairways, reinforcement, … are managed centrally in 1 model.
Within Allplan an overview list with steel profiles is made up and the desired views and cuts can be generated. For presentation purposes, the steel structure can be made up with colours, textures, environmental objects such as thegrounds, the background (trees, people, …), in this way photo-realistic images are created, stationary or moving.

Allplan also disposes of a ‘one-file’ approach. A lot of drawing software is not built-up with regard to projects but is based on one single file, e.g. DWG, dgn, dxf. Allplan has the disposal of both possibilities; the recommended ‘projects’ approach (prj), as well as the ‘one-file’ (ndw) approach. In this way, the changeover from your present drawing software to Allplan is done without much retraining. All the same, an approach ‘by using projects’ is much more advantageous when working in a multidisciplinary way to one virtual building model.

The modernised dimension lines and text layout attract the attention in the basic modules. In the architecture module, the macro for windowsills is new and the module for stairways is improved. Allplan Engineering offers the possibility to reinforce ‘floors and walls with openings’ in one routine with bars that possibly have various bending spots. In the module ‘section modeller’, in which it is possible to model bodies based on a 3D section with variable cross-sections, it is now possible to have the cross-section tipped alongside the incline of the section but also to keep it vertical according to the absolute verticality. For clients with a license server it is now also possible to log out a workstation from the network in order to work locally with software protection.

SCIA-software is also used at universities and colleges during the courses, practices and for theses. It happens quite often that a thesis is entered in a contest and that it receives a prize. On repeated occasions this has been the case with the ‘Student Steel Prize’.

Recently, Mr Ben Cools, student at the ‘Vrije Universiteit Brussel’, submitted to us a very interesting thesis. It regards a comparative study between the Belgian standards and the Eurocodes. It has been carried out in cooperation with Victor Buyck Steel Construction from Eeklo. Prof. ir. Wim Hoeckman, university teacher for steel structures and bridge construction, acted as his supervisor. For this study, the new bascule bridge ‘Boulevardbrug’ of Willebroek has been recalculated according to the Eurocodes, originally the bridge was calculated taking the Belgian standards into account. The recalculation has been executed, just like the original calculation, with the SCIA software solution ESA-Prima Win.

The bridge has a span of 65m, the largeness is 16m, it weighs 900 tons and the counterweight is 1200 tons. Image by Ney & Partner.

The study:

In general, the Eurocodes prescribe lower but more concentrated traffic loads. On the one hand, they have a favourable influence on the transversal supports but on the other hand they cause a more unfavourable loading of the orthotrope road surface. The simple fatigue check is considerably more severe than the Belgian standards; there is absolutely no possibility to take the opening and closing of the bridge into account. A check by means of the reservoir method is on the other hand possible and the results are always more favourable than both other checks.

Further on, the Eurocodes don’t give calculation rules or methods for a simplified check of the general stability. A second order calculation shows that the method with retaining forces, as prescribed by the Belgian codes, provides very conservative results. In this way, a rather big save in weight can be realised in the frame structure of the bridge.

The Eurocodes incite the developers to use more accurate methods with the aim of obtaining more favourable results. These methods are sometimes more time-consuming but this is largely intercepted and compensated by the availability of specialised software such as ESA-Prima Win and SCIA.ESA PT.

The checking of the orthotrope road surface has however no benefit from this new calculation, it is considerably more severe than the check according to the Belgian codes. Finally it should be mentioned that the Eurocodes don’t give wind loads in the case of opening movable bridges.

Importance of the calculation software:

As the Eurocodes offer more facilities for accurate calculations, it is indispensable that the calculation software connects seamlessly with the codes. The global stability control and the non-linear analysis clearly provide a gain. It also appears that the more strict results of the Eurocodes regarding the orthotrope road surface can be compensated partially by using a detailed finite-element-model. The provisions for mobile loads in ESA-Prima Win allow for tracking the critical points in the structure, in a fast and simple way, notwithstanding the more complex calculation rules of the Eurocodes.

If it were up to SCIA, Ben Cools would win the highest award for this thesis.