考虑塑性变形发展程度系数的RC梁开裂弯矩改进计算公式

An improved formula for cracking moment calculation of RC beams considering the development coefficient of plastic deformations

针对RC梁开裂荷载计算方法尚未统一的现状,首先,结合18根RC梁试验数据对比了已有的6种RC梁开裂弯矩计算公式,发现开裂弯矩理论计算值与试验值的偏差大小和混凝土强度有关;然后,通过提出塑性变形发展程度系数k,推导新的RC梁开裂弯矩计算公式,并进一步基于k值和塑性影响系数计算值γk进行改进;最后,选取12根RC试验梁验证改进公式的准确性,证明改进公式的计算值与试验值吻合更好且偏于安全。

In view of the lack of a general method for calculating the cracking loads of RC beams,6 different formulas for calculating cracking moments were first compared using 18 experimental RC beams.The results showed that the deviations between the calculated and experimental cracking moments were related to the concrete strength.Then a new concept of plastic deformation development coefficient,k,was proposed in order to derive a new cracking moment formula.The formula was further improved based on k and the influence coefficient of plasticityγk related to k.The recommended values of k andγk were given according to the concrete strength.Lastly,12 experimental RC beams were used to verify the accuracy of the improved formula.It was found that the estimations by the improved formula agreed well with the experimental measurements and was more conservative than the existing formulas.