Renovating the Van Brienenoord Bridge Steelwork in mechanical system of bascule bridge spanning 50m.

The Van Brienenoord Bridge is a large bridge which includes three movable bascules. The two oldest bascules stem from 1965. A study into renovation and/or replacement of these bascules has been performed and replacement was deemed necessary. A new design for the mechanical driving system has been made, where the design of the western bascule served as starting point. The regulations and requirements have become more stringent since 1965, however the available space is restricted by the existing concrete structure. A steel rack and pinion design is chosen as the best option for the mechanical driving system. In the design of the steel rack, several considerations have been made with respect to the material choice. A fully welded construction was desired due to the lower weight of the construction. However, stringent requirements are made with respect to the hardness, yield strength and tensile strength in several locations of the rack. After considerable calculations and consulting suppliers/manufacturers the tooth rack will be made of 25CrMo4 as the best compromise between material properties and weldability. The pinion material is selected as 34CrNiMo6 since weldability is not an issue. The choice here has to do with the minimum required mechanical properties (even above‐normative refinement). The connection to the concrete structure consists of an eye which is rather big and bulky. This is considered to be rather conservative due to the calculations methods and leaves room for optimisation.