摘要
为改善大跨PC连续刚构桥因设计阶段应力储备不足引起后期运营阶段桥梁开裂和下挠问题,通过分析大跨PC连续刚构桥结构应力状态和混凝土强度理论,提出桥梁设计阶段正截面最小压应力储备值概念,推导出桥梁在设计阶段跨中梁段应预留的正截面最小压应力储备值计算式。以3座大跨PC连续刚构桥为例,对储备值计算式的可行性进行算例验证,结果表明:正截面最小压应力储备值计算公式解与实桥有限元解的误差最大值为4.5%,满足设计要求;正截面最小压应力储备值与桥梁跨径有关,桥梁跨径越大正截面最小压应力储备值越大,跨径越小正截面最小压应力储备值越小;该计算式适用于大跨PC连续刚构桥,对其它结构体系桥梁正应力储备值应另行研究。
The insufficient design stress reservation of long-span continuous rigid-frame bridge is a cause of latent cracks and deflection in a bridge in its service period.In this study,the structural stress condition and concrete strength theory of the long-span PC continuous rigidframe bridge was analyzed,based on which the concept of the minimum compressive stress reservation value for the normal section was proposed in the design stage,and the calculation formula for the minimum compressive stress reservation value in the midspan normal section in the design stage was deduced.Three actual long-span PC continuous rigid-frame bridges were taken as the examples to do calculation verification of the feasibility of the calculation formula of the reservation value.The verification indicate that the results gained from the calculation formula of the minimum compressive stress reservation value in normal section has a 4.5% difference from the values gained from finite element calculation of the actual bridges,satisfying the design requirements.The minimum compressive stress reservation value in normal section is correlated with the span length of the bridges,as the longer the bridge span is,the greater the minimum compressive stress reservation value in normal section will be,and vice versa.The calculation formula is applicable to long-span PC continuous rigid-frame bridge,whereas the normal stress reservation value of bridges of other types is another thing,which calls for other studies.
出处
《世界桥梁》
北大核心
2016年第2期64-67,72,共5页
World Bridges
基金
陕西省交通运输厅科技项目(13-25k)
关键词
连续刚构桥
预应力结构
开裂
下挠
压应力
储备值
设计
有限元法
continuous rigid-frame bridge
prestressing structure
crack
deflection
compressive stress
reservation value
design
finite element method
