No abstract

The Gyeongbu high-speed railway (KTX) in Korea has been open to the public since 2004. Since one third of the railway is lying on bridges, a two-span continuous pre-stressed concrete one-cell box girder with 40 m span length was chosen as typical bridge. However, field measurement showed that the chosen bridge type does not satisfy the required design acceleration response of 0.35g under certain circumstances owing to various factors such as rail irregularity, impact owing to discontinuous ballast–sleeper contact, train condition including wheel and interaction between bridge and moving train. This paper intends to find out a measure to control the vibration by changing the structural properties of the originally chosen bridge type. First, a damper system was proposed. Numerical analysis showed that a damper at mid-span could reduce the response by 20 per cent. Accordingly, various types of dampers were installed and compared, but this solution was discarded owing to maintenance cost. Second, added mass solution was proposed. Numerical analysis and scaled-down model indicated that the additional mass could reduce the response by 20 to 40 per cent. Consequently, sand bags of 31.2 tons were dumped at the centre of each span and enabled the vertical acceleration response of the bridge to be successfully controlled in compliance with the design requirements.

As vehicles become more intelligent, in-vehicle networking (IVN) systems such as controller area network (CAN) are essential for the convenience and safety of drivers. To expand the applicability of IVN systems, attention is currently being focused on chassis networking systems that require increased network capacity and real-time capabilities. FlexRay was developed to replace CAN protocol in chassis networking systems, to remedy the shortage of transmission capacity and unsatisfactory real-time transmission delay of conventional CAN. However, FlexRay network systems require a complex scheduling method, which is a barrier to their implementation as chassis networking systems. In particular, if we want to migrate from a CAN network to a FlexRay network using the well-defined CAN message database, which has been specifically constructed for chassis networking systems by automotive vendors, a new type of scheduling method is necessary to reduce scheduling efforts during the software development process. This paper presents a node-based scheduling method for easy migration from a CAN network to a FlexRay network system. To demonstrate the feasibility of the technique, its performance is evaluated in terms of various software complexity indices.