Keywords: steel joints, connections, resistance, stiffness, component method, MS Excel, Eurocode 3 part1.8.

In the framework of an industrial plant renovation, BG Consulting Engineers was confronted with checking the structural safety of around 1500 steel connections. These connections (bolted flush/extended end-plate) were designed fifteen years ago, according to the procedures available by that time, i.e. SZS Tables and hand calculations using the "reduced rigid plastic" method. An assessment of the connections resistance had to be made following SIA263 and Eurocode 3 which, in some cases gives resistance values below (30%) the original values.

Even if some repetition was found, the volume of unique joint geometries (about 900 unique configurations) required an automatic or semi-automatic calculation procedure. The software available in the market did not cover all the geometries and joint configurations; therefore it was decided to implement our own application. Excel spreadsheets and macros were used to allow for complete control over the whole process.

The component method of Eurocode 3 was followed. Some of the geometries were not covered explicitly by Eurocode 3 part 1.8 (e.g. connections with four bolts per row). Hypothesis and judgements had to be made and then validated using finite element models.

This paper describes the procedure implemented which allowed for considerable time savings and state of the art structural verifications. The automatic procedure allowed for batch processing of connection tables, having individual result reports per connection exported in PDF form. The results include joint resistance (bending moment, axial and shear force) and joint stiffness estimations and detailed partial results, as resistance per row and critical components. A classification according to the joint stiffness (as pinned, semi-rigid and rigid) was also made.

The Excel application admits tabular input or individual connection design (including welds) and a module to design connection reinforcements (haunches or additional bolt rows). The engineer has access to the results (e.g. safety ratio) and is able to see the influence of any modification introduced.

The future development of an intelligent connection designer using this application and a genetic algorithm is discussed.

BG Consulting Engineers' spreadsheet is able to generate finite element (working as a pre-processor for EDF CODE-ASTER) and NASCon (nonlinear analysis of steel connections software) models to compute the complex non-linear moment-rotation behaviour of the joint.

The implemented system manages the lists of results and produces individual detailed reports which were very interesting features in terms of time-saving and effective control over a large amount of data.

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