Evaluation of Factors on the Concrete Breakout Strength of Bridge System Considering the Constant Dead Load

초록

Bridge bearing anchors support a significant amount of dead load from the superstructure of the bridge. The current design standards of anchors based on the CCD method do not account for the effect of the dead load on the behavior of the anchor. For this reason, bridge anchors have been assessed to be deficient in the seismic performance, leading to yearly unnecessary repair and reinforcement for the anchors. Thus, experimental and numerical studies were performed to evaluate the effect of a constant dead load on the concrete breakout strength of bridge bearing anchors. The experimental study showed that the concrete breakout strength of the bearing anchor considering the dead load of 1.0 and 2.0 times the expected concrete breakout strength increased by 1.8 and 2.0 times that without the dead load, respectively. In addition to the experimental data, a numerical analysis model was validated to analyze the effect of dead load on the concrete breakout strength in bridge bearing anchors. The numerical analysis involved the dead load ranging from zero to 4 times the expected concrete breakout strength. The results of the numerical analysis showed the increase in the concrete breakout strength with increasing the dead load. Furthermore, this study evaluated the effects of the other main parameters, such as friction coefficient, concrete compressive strength, edge distance, and base plate area, on the concrete breakout strength of bridge bearing anchors subjected to compressive and shear forces. When the friction coefficient between the surfaces of the bridge bearing and base plate increased from 0.1 to 0.9, the concrete breakout strength increased slightly by approximately 24 kN for a dead load of 250 kN. This means that the friction force generated by the friction coefficient with the action of the dead load has an insignificant effect in the concrete breakout strength of the bearing anchor. The change in compressive stress owing to the change in the base plate area was