연속화된 다단계 프리스트레스트 콘크리트 거더의 긴장력 손실 저감

Abstract

Prestressed concrete girder bridge has been one of the most widely used bridges in the world because of its excellent construction feasibility, economic efficiency, serviceability, and safety. In certain situations, the prestressing tendon is supposed to be bent by the construction error and the radius of curvature at the continuous joint of PSC girders, and this leads to the loss of prestressing force. However, this kind of prestress loss is not considered in the design and construction processes. This study proves that the prestress loss occurs at the continuous joint due to the local bending of tendon by the construction error or the radius of curvature. Also, a method that can reduce this type of prestress loss is proposed, and proved by the experiment. The result shows that approximate 8.8% of prestress loss occurs at the continuous joint and the proposed block-out method can reduce the prestress loss ratio approximate 5.6%, on average. This means that the block-out method can enhance the prestressing efficiency of continuous PSC girder bridges. Also in another certain situations, anchorage slip may cause excessive prestress loss during prestressing. So, comparative test shows the reason between single-acting ram and double-acting ram in same external environment. The anchorage slip with double-acting ram cause 11.6% of prestress loss while anchorage slip with single-acting ram cause 20.7% of prestress loss, prestressing with double-acting ram can reduce about 9% of prestress loss on average.