| 摘要 |
A prestressed concrete girder (20) has an adjustable load bearing capacity so that the tension of a steel wire (26, 27, 29) is adjusted as necessary. The prestressed concrete girder having an adjustable load bearing capacity in a bridge includes at least one non-attached steel wire installed at an upper flange (28) of the girder in a lengthwise direction of the girder, in which the heigh of the bridge is reduced, the span of the bridge is increased, or a long-term crack or sagging of the bridge is compensated for by adjusting tension of the steel wires when the bridge is under construction, or after laying of slab or completion of construction. A method of adjusting a load bearing capacity of a bridge using the above prestressed concrete girder is achieved by installing the girder over a pier, cutting step by step the non-attached steel wires according to the amount of a load applied to the girder installed at the pier when the bridge is under construction, and cutting step by step the non-attached steel wires according to the amount of sagging of the girder during a use of the bridge after the construction is completed. Thus, when an excess of sagging or a crack is generated to a bridge due to long-term deterioration or overload, the sagging of a girder and crack can be compensated for by releasing the tension of the steel wires provided to the upper flange step by step, or when there is a need to increase the load bearing capacity of the bridge without any particular damage to the bridge, the load bearing capacity of the bridge can be easily increased with no special equipments. |
