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Systematic Analytical Model and Design for Torsional and Flexural Strength

扭转和弯曲强度的系统分析模型和设计

基本信息

批准号：
06452260
负责人：
SAEKI Noboru
金额：
$ 2.3万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06452260/
关键词：
Torsion Bending Shear Space truss model RC plate model Effective cover Warping Diaphragm RC平板モデルせん断ひずみ St.Venantのねじりねじり剛性

项目摘要

(1) Ultimate strength and failure modes of reinforced concrete member subjected to combined torsion, bending and shearThe space truss theory is advanced by superposing torsional, bending and shear force, and fundamental equations are derived. By using an iterative method stress and strain can be calculated and checked on the failure. Failure modes are classified as 1)yielding of transverse bars, 2)crushing of diagonal concrete struts, 3)compressive-shear fracture of compressive region and 4)flexural fracture. According to the comparison with the calculated values and results of experiments, the proposed method is available to predict the ultimate strength and failure mode under arbitrary combined loads of torsion, shear and bending.(2) Deformation of reinforced concrete member subjected to torsionAt first, the effective cross section for torsion is assumed to reinforced concrete plates with and without cracks. Then fundamental equations are derived from equilibrium conditions and compatibility conditions considering tensile stress of concrete. Spalling of cover of concrete at post cracked region is estimated by effective cover using the proposed index of shear strain at cover. Though calculated deformation tends to estimate conservatively in comparison with test results, it is shown that this method predicts approximately torsional deformation.(3) Torsional behavior of reinforced concrete member with diaphragmsTorsional behavior of reinforced concrete member with diaphragms is evaluated. The warping stress occurs because warping is confined by diaphragms, therefore mixed torsion theory is applied. According to the comparison with the calculated values and results of experiments, it is found that the proposed method evaluates torsional stiffness in the region before crack occurs.

(1)钢筋混凝土弯扭剪复合受力构件的极限承载力和破坏模式本文提出了将扭、弯、剪力叠加的空间桁架理论，导出了基本方程。采用迭代法可以计算应力和应变，并对破坏进行校核。破坏模式分为：1）横向钢筋屈服，2）混凝土斜压杆压溃，3）受压区压剪断裂和4）弯曲断裂。通过与计算值和试验结果的比较，表明该方法可用于预测任意弯、扭、剪组合荷载作用下的极限强度和破坏模式。(2)钢筋混凝土受扭构件的变形首先，假定有裂缝和无裂缝钢筋混凝土板的有效受扭截面。在此基础上，根据混凝土的平衡条件和协调条件，推导出考虑拉应力的基本方程。采用建议的保护层剪应变指标，用有效保护层来估算开裂后保护层的剥落。尽管与测试结果相比，计算变形往往会保守估计，但研究表明，该方法可以大致预测扭转变形。(3)带横隔板钢筋混凝土构件的抗扭性能本文对带横隔板钢筋混凝土构件的抗扭性能进行了评估。翘曲应力的产生是由于翘曲受到横隔板的约束，因此采用混合扭转理论。通过与计算值和试验结果的比较，发现该方法能够准确地计算出裂纹发生前的扭转刚度。