缺陷PC梁式桥刚度退化-预应力损失的耦合评估模型  

Coupling Evaluation Model of Stiffness Deterioration & Prestress Losses for Deficit PC Beam Bridges

作　　者：郭琦[1,2] 尹海军[1,2] 

机构地区：[1]西安建筑科技大学土木工程学院,陕西西安710055 [2]长安大学旧桥检测与加固技术交通行业重点实验室,陕西西安710064

出　　处：《中国公路学报》2016年第1期75-81,88,共8页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(51108372);中央高校基本科研业务费专项基金项目(310821151109);陕西省自然科学基础研究计划项目(2015JM5195);陕西省重点学科建设专项资金项目(E01004);陕西省教育厅专项科研计划项目(15JK1391)

摘　　要：为准确评估开裂预应力混凝土梁式结构桥在使用阶段的变形性能,以虚拟消压力作用距离为基点对预应力增量、普通钢筋及翼缘受压区混凝土应力进行了级数展开,进而依据截面平衡关系推导了开裂截面刚度的显式解析式。结合前期基于钢束有限测点应力检测值实现有效预应力纵向实际分布状态预测的研究成果,得到了全桥各关键截面有效预应力衰变因子的分布规律。在二维梁单元模型的基础上建立了考虑结构刚度退化与预应力损失耦合关系的修正模型,并与传统的开裂截面中和轴高度一元三次方程的迭代解进行对比;将结构刚度退化模型应用于室内模型桥试验,并开展了敏感性分析。结果表明:2阶显式解的精度较高,能够用于不同预应力损失状态下的截面刚度变化模拟及正常使用状态评估限界的界定;在使用荷载作用下的弹性开裂阶段,结构的变形评估曲线与试验曲线吻合较理想;该模型易于编程应用,可在服役预应力混凝土桥梁检测与评估实践中推广。In order to accurately evaluate the deformation capacity on cracking prestressed concrete bridges in service stage,the distance of virtual force was taken as the base point and prestress increment,reinforced bar and wing stress in pressed concrete area were formed in series expansion.Furthermore,the explicit function of cracking sectional stiffness was derived from sectional equilibrium.Combining the previous research results which managed to predict the longitudinal practical distribution condition of effective prestress from limited inspecting points,the distribution principle of deteriorative factors on effective prestress was obtained in key sections of the whole bridge.The correction model considering coupled relationship between stiffness deterioration and prestress losses was established based on two-dimensional beamelement model,which was compared with the iterative solution to one basic cubic equation of natural axis height on cracking concrete section.Structural stiffness deterioration model was applied in indoor model bridge test and sensitive analysis was conducted.The results show that the second-order solution with relatively high accuracy may be adopted to simulate sectional stiffness change in different prestress losses and to confine the serviceability limit state.The fitting of structural deformation evaluation curves and test curves come to be more satisfied in the stage of elastic cracking under the effect of loading.The evaluation model is convenient to program and worth to utilize in inspection and evaluation on existing PC bridges.

关 键 词：桥梁工程 梁式桥 显式解析 预应力损失 截面刚度 结构刚度 

分 类 号：U448.21[建筑科学—桥梁与隧道工程]