When designing bridges for project proposals, you need to be sufficiently accurate to ensure both that your price is keen and the structures are adequate. And you usually need to do this within a very tight deadline.

Here is a fast-track technique for achieving all these goals: in fact one engineer recently said that he would be able to do 6 schematic designs in a day, rather than his normal single bridge per day, and still meet his quality standards.

Whether the construction uses steel composite beams, precast pretensioned beams or reinforced concrete beams, the technique is the same. Let us suppose that one of the proposed bridges has spans of 24m, 42m and 36m. We do not have the time to generate complex models, so we will use line beam analysis as follows:

1. Define three beams in the Beams module of SAM-LEAP5
2. In the Line Beam module of SAM-LEAP5 define a simple three span structure, and associate the previously defined beams to the correct spans.
3. Calculate the dead load effects for the beams using the automated process
4. Use live load optimisation technique to determine the envelopes for moment and shear due to BD 37/01 loading.
5. Transfer dead loads and live load envelopes to Beams module.
6. Check that the design neither fails not is too conservative.
7. Go on to the next structure É total time spent probably less that an hour and a quarter.

Step 5 requires assumptions regarding the transverse distribution of live loads, but here again SAM-LEAP5 makes this fast, easy and accurate by incorporating the distribution factors from the American design codes, which are empirical factors calibrated by dozens of test configurations for various typical structures.

Here is a quote from Case Study #3: "Of course the main benefit of using the process [Integrated Bridge Design] is the massive time savings achieved over using more traditional or non-integrated optimisation programs." The process outlined above is a classic example of this.

If you would like to see exactly how this time saving can benefit your organisation please contact us and we can arrange a short demonstration at your offices.