关键词: 多跨长联桥, 悬臂施工, 支座摩阻力, 预加力次轴力, 桥梁设计

Abstract: As to long multi-span prestressed concrete continuous girder bridge in cantilever casting construction,when the closure strands is pulled,the pre-applied force in the closure strands compresses beam body to cause the lateral deformation,and one side bearing-friction resistance at closure-mouth will restrain beam body to avoid the lateral deformation,therefore the pre-applied force hyper static axial force is generated.Hyper static axial force,which is a kind of hyper static internal forces just like hyper static moment,is representd generally as tensile force in post tensioned members.From the aspect of bending or cracking resistance capacity,hyper static axial force would make a disadvantageous effect on the post tensioned concrete structures.Based on a 14 cross long multi-span prestressed concrete continuous girder bridge in cantilever casting construction,hyper static axial force resulting from each cross closure strand is calculated.Then the principle,distribution characteristic of the hyper static axial force,as well as the measure of reducing hyper static axial force are discussed.Finally on the base of rorms,pre-applied force hyper static axial force is considered to increase.The formula which is used to design the right section anti-moment and the anti-crack checking for multi-span continuous girder bridge is proposed.

Key words: long multi-span bridge, cantilever casting, bearing-friction resistance, pre-applied hyper static axial force, bridge design