SELECTION OF A CONCRETE BRIDGE GIRDER CROSS SECTION

In concrete bridges, a structure's own weight often represents the most important part of the total load of the structure. Therefore, a reduction in the own weight of the bridge girder has a favourable effect not only on the cost of the bridge girder itself, but also on the supporting and foundation structures of the bridge. This reduction in weight can be realized by selecting a convenient shape and size of the bridge girder's cross-section. In specific cases a high performance concrete can be used. The convenient shape and size of the cross-section should perfectly satisfy the requirements of safety, durability and serviceability, including an adequate dynamic response of the whole bridge structure. Compared to normal concretes, the relative increase of strength in high performance concretes is larger than the relative increase of the elasticity modulus. The right choice to use high performance concrete for bridge constructions can only be evaluated on the basis of structural optimisation. This paper exposes the developed computational method and software for the purpose of optimising the cross-section of a bridge girder. In our search of optimum solutions we also explored, apart from modifying cross-sections, the possibility of using high performance concretes. Based on the analyses performed we discussed the conditions under which the use of high performance concretes for bridge construction can be recommended. The application of the developed computational method and software is presented by two computational examples.

• INTRODUCTION

• ANALYSIS OF THE STRUCTURE

• OPTIMISING THE CROSS-SECTION OF THE BRIDGE GIRDER

• COMPUTER PROGRAMMING

• COMPUTATIONAL EXAMPLES

• CONCLUSIONS

• REFERENCES