刘婷, 薛伟辰, 王巍. 全预应力混凝土梁长期变形计算[J]. 工程力学, 2016, 33(9): 116-122. DOI: 10.6052/j.issn.1000-4750.2015.01.0069
引用本文: 刘婷, 薛伟辰, 王巍. 全预应力混凝土梁长期变形计算[J]. 工程力学, 2016, 33(9): 116-122. DOI: 10.6052/j.issn.1000-4750.2015.01.0069
LIU Ting, XUE Wei-chen, WANG Wei. CACULATION ON LONG-TERM DEFLECTIONS OF FULLY PRESTRESSED CONCRETE BEAMS[J]. Engineering Mechanics, 2016, 33(9): 116-122. DOI: 10.6052/j.issn.1000-4750.2015.01.0069
Citation: LIU Ting, XUE Wei-chen, WANG Wei. CACULATION ON LONG-TERM DEFLECTIONS OF FULLY PRESTRESSED CONCRETE BEAMS[J]. Engineering Mechanics, 2016, 33(9): 116-122. DOI: 10.6052/j.issn.1000-4750.2015.01.0069

全预应力混凝土梁长期变形计算

CACULATION ON LONG-TERM DEFLECTIONS OF FULLY PRESTRESSED CONCRETE BEAMS

  • 摘要: 与部分预应力混凝土梁相比,全预应力混凝土梁全截面受压且压应力较高,由于混凝土收缩徐变产生的梁长期变形也更大。该文从按龄期调整的有效模量法出发,将梁沿长度方向细分单元,细分单元长度为截面高度的1倍~2倍,锁定单元节点,分别计算混凝土的收缩、徐变以及预应力筋的松驰对其产生的强迫力值;释放强迫力,并将其反向作用于节点上,求出此时的截面时随应变和附加曲率,进而推导出可用于求解任意时刻的全预应力混凝土梁长期变形的计算公式。基于该课题组和其他研究者试验结果,对该文及国内外规范的计算公式进行了对比分析,结果表明:该文公式计算值与试验结果吻合良好;国内外规范计算值与试验结果的平均误差则明显偏大,且计算结果偏于不安全。

     

    Abstract: Compared with partially prestressed concrete beams, fully prestressed concrete beams stays compressed status of whole section with higher stresses, which results in excessive long-term deflections due to creep and shrinkage of concrete. Based on the Age-adjusted Effective Modulus Method (AEMM), the beam was divided into several elements along the span and the length of the element was one to two times the height of section. The changes of strain and curvature due to creep and shrinkage of concrete and relaxation of prestressed tendon were first artificially restrained by application of an axial force and a bending moment on the nodes of the elements. Subsequently, these restraining forces were removed by the application of equal and opposite forces on the nodes of the elements, resulting in changes in strain and in curvature. A theoretical formula for long-term deflection of fully prestressed concrete beam at the mid-span was derived. Base on the test results of our group and other researchers, the calculated values using the suggested formula were compared well with the test results. However, the calculated errors using design codes were larger, which resulted in unsafe results.

     

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