既有预应力结构现存预应力数学模型研究

Study on the Existing Mathematical Models of Extant Prestressed Structures

以福建省福州市鳌峰闽江大桥为研究背景,建立该既有结构三维有限元模型,在外荷载分级作用下,获得随着预加力变化的梁体挠度响应,以研究桥梁挠度与既有桥梁现存预应力之间的关系。采用数学优化分析软件1st Opt 6.0程序对构件各代表性截面的预应力损失度及对应的挠度响应进行拟合,建立了三个代表性截面预应力损失度与挠度增量之间的数学模型,数学模型的拟合相关系数均达到0.98以上。通过该数学模型,利用静力分级加载试验获得的挠度增量代入所建立的数学模型就可以获得预应力损失度,进而计算出结构现存预应力.最后将推导结果与应力释放法试验结果进行对比,误差在5%以内,证明了所提数学模型的有效性和实用性。

Minjiang bridge in Aofeng,Fuzhou,Fujian was taken as the research background. In order to study the relationship between the deflection and the existing prestress of the extant prestressed concrete structure,the deflection response with the change of prestress under stepped outer loads was obtained with the establishment of three-dimensional finite element model of the existing structures. The degrees of prestress loss of 3 representative sections and the corresponding deflection responses were fitted by using mathematical optimization analysis software 1st Opt6. 0 components.And then a mathematical model was established according to the deflection increment of the three representative sections and the loss of prestress,with which the fitting correlation coefficient reached 0. 98 or above. The degree of prestress loss can be calculated using the mathematical model by inputting the deflection increment obtained from the static load grading test. The error is within 5% by comparing the test results of stress release method with the derived results,which proves the effectiveness and practicability of the proposed mathematical model.