Takahiro Ichikawa
Research and development of the Reinforced concrete joint structure for medium-scale concrete bridges
Masatsugu Nagai
Water leakage from expansion joints have frequently damaged a concrete girder bridge at near its supports. Therefore, prevention of water leak is an urgent issue. At present, a variety of methods removing the expansion joints such as integral abutment, expansion slab system and so on has been proposed. Reinforced concrete joint structure (RCJS), which connects an expansion joint with reinforced concrete for medium-scale concrete bridges, is a new method among them. Its merits are easy construction and low cost.
The objective of this study is research and development of RCJS. On-site measurement, experiments and numerical calculation were carried out. The conclusions obtained from this study can be summarized as follows.
On-site measurement and finite element analysis reveal that a bridge installed RCJS behaves such as a rigid frame bridge under live load.
It was confirmed that RCJS could be applied to a bridge whose span length is 75m or less from numerical calculations.
Experiments for RCJS that changed the shapes of reinforcing bars were conducted. Their diameter and embedded depth are 13mm and 40mm. Ultimate strengths were 148kN and 145kN for U-shaped bar and L-shaped bar (length of lap: 100mm) respectively. In addition, abutments were not damaged in both cases although reinforcing bars reached yielding. Therefore, it is better to adopt L-shaped bar for RCJS considering workability.
Ultimate strengths of RCJS under seismic loads were investigated numerically. As a result, axial forces of a RCJS under L1 and L2 earthquake became 118kN and 192kN respectively assuming that the RCJS is applied to a bridge whose span length is 40m. Comparing with experiments, the former is within allowable level and the latter reaches the ultimate state. Hence, restoration of the bridge installed RCJS subjected to seismic load is easy and rapid since only RCJS is damaged.
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