Systemanalys av plattbroar : En jämförelse inom FE-modellering och balk-/platteori

Sammanfattning: Abstract When Eurocodes was introduced, there was a requirement where the calculations had to take into consideration whether it's a slab or beam bridge. This means that calculations had to be made with softwares including plate theory. The object of this study is a slab bridge with endshields. The bridge is 66.95 meters long with a 14.38-meter-wide deck made of concrete. The deck is mounted on abutments with bearings and intermediate supports where the columns are fixed to the deck. The purpose of this study is to investigate if bridges defined as plates can be calculated using beam theory, as well as examining different modeling techniques in an attempt to evaluate how this will affect the results. A model using shell elements is established in BRIGADE/Plus and compared to a model in Strip Step 3 made out of beam elements. A base-model is also created in BRIGADE/Plus and is compared to the following modeling changes: Couplings between supports and the plate, “point to surface” or “point to point”. The bridge is modeled without wings to study the impact of the wings. The bridge is modeled without columns to study the impact of the columns. When comparing the values obtained from the two different software’s regarding deadweight, the results were almost identical. This indicates that Strip Step 3 is a suitable tool for verifying models made in BRIGADE/Plus. When studying the results from load-combination 6.10.b (the combination used for dimensioning) small differences can be seen between the softwares. This concludes that it may be reasonable to use Strip Step 3 for this type of bridges. However, there are major differences between the software at the traffic load which should be considered. In order to simplify the modeling process ties between points (nodes) should be used. However, the results obtained over the supports must be ignored due to unrealistic values. When studying the impact of wings/columns it was confirmed that a difference of 10 % appeared. Modeling without wings/columns is not more time efficient either, with that in mind wings and columns should be used when modeling.   Keywords: Plate theory, Beam theory, Strip Step 3, BRIGADE/Plus, FE-modeling