The Railway Technical Research Institute (RTRI) has established a new structural design method for over-track low-rise buildings such as stations by examining requirements and evaluation techniques.
In the conventional design method, footing beams in the track direction need to be set up, while those perpendicular to the track may be omitted. However, examination based on a series of analyses has shown that the footing beams in the track direction set up under the platform can also be omitted by increasing the proof stress and rigidity of piles and through a clear understanding of the behavior of piles when an earthquake occurs (Fig. 1).
The new design method adopts non-linear analysis of integral construction made up of ground - piles - buildings in terms of stress/deformation analysis rather than conventional elasticity analysis. Thus the behavior of the structure up to large deformations can be grasped and the influence of an absence of footing beams can be integrated into the design. The design also conforms to diversification of piles and pedestal engineering methods.
This new method makes it possible to omit footing beam construction work under the platform, and a cost reduction of about 10% is expected for framing construction on over-track artificial ground.
The above results have been reflected in the revised edition of the current design standard "Standard for Structural Design of Over-Track Low-Rise Buildings." Plans for over-track station enlargement are already underway based on this design standard, and further widespread use of this method is expected, including JR and private railways.