Design of joint sections of a steel-concrete composite bridge

Abstract

The Arinogawa Bridge designed by the authors is one of the longest steel-concrete composite bridges on the Shin-Meishin Expressway. The dimensions of the bridge are as follows: 364 m for the inbound lane, 363 m for the outbound lane, and 448 m for the ramps. In the Arinogawa Bridge, there are seven joint sections of steel girders and PC girders, and some of these joint sections are located in junctions between the through lane of the bridge and the ramps. The authors considered that these joints would be placed under complex stress, and there was a possibility that the stress might exceed the expected levels. To solve this problem, the authors employed special countermeasures both in the design and the construction process. The countermeasures related to design consisted of creating a full-bridge model and implementing FEM analysis. In the FEM analysis, a model of the entire bridge was created, and precise calculations were conducted of the complex stress distribution in the event that live loads act on the joint sections in the most adverse manner. The countermeasures related to construction consisted of tests conducted to confirm that concrete is filled properly into full-scale specimens of joints, because the narrow steel cells placed in the joints must be tightly filled with concrete without compaction. Meanwhile, since the project owner was delayed in acquisition of land for construction of the bridge, the construction process had to be curtailed significantly. All cast-in-place slabs to be installed on top of the steel girders were replaced with pre-cast slabs (a total of 183 slabs with an overall slab area of 3,560 m2).