钢筋混凝土剪力墙轴拉试验和轴拉刚度理论分析

文章完成截面纵筋率为17%、25%的钢筋混凝土剪力墙轴拉试验。试验结果表明：剪力墙轴拉刚度在混凝土开裂前由钢筋和混凝土共同提供，并随轴拉力的增加逐渐下降；在混凝土开裂时轴拉刚度迅速下降；在开裂后混凝土退出工作，轴拉刚度逐渐趋于截面纵筋刚度。基于试验结果，完成剪力墙的轴拉受力特性和刚度变化特征的理论分析，提出能够描述钢筋混凝土剪力墙轴拉刚度变化特征的二阶段计算方法：在混凝土开裂前及开裂时根据混凝土本构模型获得的受拉弹性模量进行计算，在开裂后则引入纵向受拉钢筋应变不均匀系数进行计算。由此得到的理论值与试验结果更为吻合，更能反映剪力墙在轴拉阶段的受力和刚度变化特征。

Theoretical analysis of axial tensile stiffness and experiment study on tensile#br# performance of reinforced concrete shear wall

The axial tensile tests were performed for reinforced concrete shear wall with sectional longitudinal reinforcement ratio of 1.7% and 2.5%, respectively. Based on these tests, the tensile stiffness of the shear wall is shared and provided by reinforcement and concrete before concrete cracks, and gradually decreases with the increase of the axial tension. When concrete cracks, the tensile stiffness of the shear wall decreases rapidly. After cracking, concrete can’t bear the load any more, and the axial tensile stiffness gradually approaches the sectional longitudinal stiffness of the reinforcement. Furthermore, theoretical analyses on the axial tensile characteristics and stiffness variation characteristics of the shear wall are conducted. A two-stage calculation method is proposed for describing the axial tensile stiffness variation characteristics of the reinforced concrete shear wall. In this method, the tensile modulus is calculated by using the concrete constitutive model before and during cracking of concrete, but after cracking of concrete, a strain uniformity coefficient of longitudinal tensile reinforcement is introduced for the calculation. The theoretical values obtained by the proposed method agree well with the experiment results, and it can better reflect the stress and stiffness variation characteristics of the shear wall during the axial tensile stage.