大跨度张弦桁架预应力张拉控制研究

应用有限元软件ANSYS，通过对模拟千斤顶升温的模拟千斤顶法实现拉索预应力，提出了张弦桁架预应力的实用确定方法．将使用状态下计算得到的千斤顶温度荷载加到施工状态的计算模型即可求出施工需控制的索力、控制点位移．二次张拉需考虑张拉对相邻桁架的影响，施工控制难度大，本文结合哈尔滨会展体育中心支座跨度128m的超大跨度预应力张弦桁架结构的深化设计计算，提出了单榀张弦桁架下弦拉索胎架一次张拉法施工方法，通过对张拉阶段胎架与张弦桁架间摩擦力的计算研究，定量索力下跨中位移法考虑摩擦力影响，以跨中竖向位移作为预应力张拉的主要控制指标，成功地完成了该工程预应力张拉施工．

Research on prestress stretching control of a large-span truss string structure

Cable prestress is simulated with a jack and realized by increasing its temperature through finite program ANSYS. An available method of truss-string structure prestress decisions is put forward. The jack temperature load calculated from the serviceability state is applied to the model of the construction state, thus the cable stress and controlling point displacement may be presented by analysis. The stretching influence on the near trusses should be considered when using the stretching-twice method, and the construction is hard to be controlled. The Harbin exhibition sports center with a 128 m support span, attached to a deep design calculation of the super-large span prestress truss string structure, stretching once in tension bed method is brought forward for the bottom cable of the single truss string structure. From calculation research on the friction force between the tension bed and the truss string structure, the friction influence is considered for the displacement method of the middle of span, with the action of the fixed cable stress. This method, with vertical displacement of the middle of span as its main control target for prestress stretching, is successfully applied in the prestress stretching construction of the project.