考虑预应力孔道影响的连续刚构剪力滞效应研究

Study on Shear Lag Effect of Continuous Rigid Frame Considering the Influence of Prestressed Duct

连续刚构在悬臂浇注施工过程中,主梁在张拉预应力之前截面存在大量的预应力孔道,对截面的削弱作用比较大,将导致翼缘板纵向应力产生变化,因此依托一座五跨连续刚构桥,建立实体有限元模型分析预应力孔道对连续刚构桥剪力滞效应的影响。研究结果表明:随着施工梁段的不断进行,预应力孔道对剪力滞的影响越来越小,在2号块施工时预应力孔道对应力的影响幅值最大,剪力滞系数增加了28.4%,当施工8号以后,预应力孔道对于剪力滞效应的影响基本上可以忽略不计。因此,本次依托桥梁在浇筑前8号块时,需要预留更大的应力储备值,以保证结构的安全,分析结果对该类型桥梁也具有借鉴意义。

In the process of cantilever casting construction of continuous rigid frame,there are a large number of prestressed channels in the section of main beam before the tension prestress,which will weaken the section greatly,and lead to the change of the longitudinal stress of flange plate.Therefore,based on a five span continuous rigid frame bridge,this paper establishes a solid finite element model to analyze the influence of prestressed channels on the shear lag effect of continuous rigid frame bridge.The results show that with the continuous construction of beam section,the influence of prestressed duct on shear lag is smaller and smaller.In the construction of 2 block,the influence amplitude of prestressed duct on stress is the largest,and the shear lag coefficient increases by 28.4%.After the construction of 8 block,the influence of prestressed duct on shear lag effect can be ignored.Therefore,in order to ensure the safety of the structure,it is necessary to reserve a larger stress reserve value for the first 8 blocks of the supporting bridge.The analysis results of this paper also have reference significance for this type of bridge.