框架-体外预应力体系下梁挠曲线计算方法

Computational method of beam deflection curve under frame-external prestressing system

以体外预应力技术对框架结构全加固后的框架梁为研究对象,分析其受力特点,建立对应的力学模型.应用力的平衡原理、点斜式求解原理和弯矩-曲率关系原理,推导索的内力表达式和索变形后的曲线表达式以及梁的荷载-挠度曲线方程,并与已有试验结果进行比较.研究表明:索内力与腹杆的轴力成非线性关系,且随索节点的垂面位置而变化;在弹性阶段,当梁挠曲线方程的边界条件无限趋近于简支梁(或嵌固梁)时,挠曲线方程的最大值与既有文献中梁跨中挠度的变化基本一致;进入塑性阶段后,挠曲线的理论值和试验值有较大的差异.弹性阶段的分析结果能够为工程实践提供理论参考.

Taking the frame beam of frame structure fully reinforced by external prestressing technology as the research object,force characteristics were analyzed and the corresponding mechanical models were established.The principles of force balance,point oblique solution and moment-curvature relation were applied to infer the expression of cable internal force and the curve expression after deformation,the load-deflection curve equation of the beam,which were compared with the previous experimental results.The results show that the internal force of cable changes with the vertical position of cable node and there is a non-linear relationship between the internal force of cable and the axial force of the web member.In the elastic stage,when the boundary condition of the beam deflection curve equation approaches infinitely the state of simply supported beam(or embedded beam),the maximum value of the deflection curve equation is basically consistent with that of the deflection of the beam in the middle span in the existing literature.While there is a great difference between the theoretical and experimental values of the deflection curve in the plastic stage.The analysis results in the elastic stage can provide a theoretical reference for engineering practice.