METHOD OF LOADING OF SURFACES OF INFLUENCE BY TEMPORARY MOVING LOAD LM1
Pages 63 - 73
In most cases, the structural analysis of temporary moving loads produced by vehicles and pedestrians involves the application of influence lines to identify the extreme forces impacting the elements of bridge structures. The application of influence lines coupled with transverse positioning ratios cannot adequately simulate the 3D behavior of structures.
The method described in this article was applied in the course of development of a draft version of National Annex to Eurocode EN 1991-2 Traffic loads on bridges to compare the load effects (bending moments and shear loads in cross sections) of temporary moving loads (SP 35.13330.2011 «Bridges and culverts» A14), and the National Annex to Eurocode 1 Part 2 (LM1).
The article represents an outline of the proposed methodology and a software programme developed in its furtherance. The software programme is capable of simulating the effect of moving loads impacting the structural elements of bridges. The software programme can also identify the most unfavourable positions of temporary moving loads on the deck of the span structure.
The introductory section of the article has an outline of LM1 load and the rules of the span structure loading. It is noteworthy that the proposed loading model and rules of loading differ from those applicable in domestic practice.
The section covering the formal representation of the surface of influence and the identification of the surface of influence contains our suggestions in terms of the user-friendly representation of surfaces of influence designated to facilitate their analysis and processing. This section also provides information about the identification of surfaces of influence through the application of the method of finite elements.
The section that covers methods of loading of the surface of influence by load LM1 has a brief overview of the computational algorithms designated for the computational representation of the loading of the surfaces of influence by load LM1. This section also has several figures to illustrate the above processes.
The implementation of the algorithms in question is provided as a sample analysis of the span structure impacted by load LM1. A regular simple reinforced concrete span serves as an example. Initial surfaces of influence, as well as their interim behavior under the impact of the load are described in the section.
The proposed methodology represents an unambiguous solution to the problem of identification of unfavourable positions of the temporary moving load LM1 (EN 1991-2) and the extreme forces or relocations involved in this respect.
DOI: 10.22227/1997-0935.2012.3.63 - 73
- BS EN 1991-2:2003 Eurocode 1: Actions on Structures — part 2: Traffic Loads on Bridges. ICS 91.010.30; 93.040; BSI; London; 164 p.
- Calgaro J.-A., Tschumi M., GulvanessianH. Designers’ Guide to Eurocode 1: Actions on Bridges: EN 1991-2, EN 1991-1-1, -1-3 to 1-7 and EN 1990 Annex A2: Traffic Loads and Other Actions on Bridges (Eurocode Designers’ Guide); Thomas Telford Limited; London, 250 p.