Fatigue cracks which initiated from the root of welded joints between deck plate and U-rib and propagated toward the surface of the weld bead (bead-through cracks) have been reported in Orthotropic Steel decks, but the fatigue strength evaluation method is not established. In this study, field investigations and FE-analysis were conducted for the bridge which bead-through cracks were found. And crack initiation point of bead-through crack was confirmed to be the same position as deck-through crack (initiates from the root of the weld and propagates through the thickness of the deck plate). In addition, fatigue damage of bead-through cracks was calculated using reference strain which proposed for deck-through crack.
Shaking table tests of small scale building model with oil damper are performed in order to verify an earthquake response magnification phenomenon caused by fracture of damper attachment member during earthquake motion. Fracture of damper attachment member is simulated by means of detachable steel block which links a oil damper with a floor plate. The steel block is detached from the floor plate at any timing by switching on an electro magnet. It is shown that the characteristics of earthquake response magnification ratios which are observed in the shaking table tests correspond well to those which are simulated by numerical analysis.
The present paper is aimed to study the behaviour of a partially concrete-filled steel tube (PCFST) under the seismic load. The PCFSTs are used as bridge piers due to the superior strength and ductility. In Japan, the diaphragm of the PCFST must be installed just above the concrete to fix the concrete and transmit the load to the concrete. However, the effect of the diaphragm on the tube behaviour is not clear. Therefore, we conducted the analysis of the PCFST subjected to the seismic load to discuss the effect of the diaphragm on the tube behaviour. Obtained results indicated the failure pattern of the PCFST was influenced by the presence or absence of the diaphragm. On the other hands, the opening size of the diaphragm give very small effect on the tube behaviour.
Corrosion of girder ends is one of the major damage for reducing the load carrying capacity of steel bridges. This research aims on proposing a practical method for evaluating remaining capacity of steel riveted girder end with section loss due to severe corrosion. Compressive loading test and elasto-plastic finite element analysis using two models were conducted for a girder end specimen which was cut out from a demolished old steel bridge in order to investigate the influence of the section loss on the remaining capacity and failure behavior.