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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)钢筋混凝土扭、弯、剪组合受力构件的极限强度和破坏模式将扭转、弯曲和剪力叠加起来，提出了空间桁架理论，并推导了基本方程。通过迭代方法，可以计算出失效时的应力和应变并进行校核。破坏模式可分为：1)横筋屈服，2)斜向混凝土压杆压碎，3)压区压剪断裂，4)弯曲断裂。通过与计算值和试验结果的比较，该方法可以预测任意扭转、剪切和弯曲组合荷载作用下钢筋混凝土构件的极限强度和破坏模式。(2)钢筋混凝土扭转构件的变形首先假定钢筋混凝土板的扭转有效截面为有裂缝和无裂缝的钢筋混凝土板。然后从考虑混凝土拉应力的平衡条件和协调条件出发，推导出基本方程。利用建议的保护层剪切应变指标，用有效保护层来估算混凝土保护层在开裂后区域的剥落。虽然与试验结果相比，计算变形趋于保守估计，但结果表明，该方法可以近似预测扭转变形。(3)对带横隔板的钢筋混凝土构件的扭转性能进行了评估。翘曲应力是由于翘曲受横隔膜的限制而产生的，因此采用了混合扭转理论。通过与计算值和试验结果的比较，发现该方法是在裂缝发生前的区域计算扭转刚度。