Skeleton curve of restoring force of diagonally reinforced ECC coupling beam based on softened strut-and-tie model

摘要

ublishercopyright>? 2019, Editorial Department of Journal of Southeast University. All right reserved.? 2019, Editorial Department of Journal of Southeast University. All right reserved. To simulate the behavior of diagonally reinforced engineered cementitious composite(ECC) coupling beam under reversed cyclic loadings, a theoretical model was proposed to predict the skeleton curve of the restoring force of the coupling beam. The proposed model was composed of the main diagonal ECC strut-and-tie, the diagonal reinforcement and the sub-struts based on the softened strut-and-tie model. The restraining effect of stirrups on the compression performance of ECC and the softening effect of ECC under compression and tension were also considered. Based on the proposed model, a formula for calculating the shear capacity of the diagonally reinforced ECC coupling beam was proposed. Eleven diagonally reinforced ECC coupling beam specimens were selected to verify the proposed model. The mean ratio of the calculated shear strength to the measured results is 0.94, and the coefficient of variation is 0.09, showing the good agreement between the calculated values and the experimental results. As for the coupling beams with the small span-to-depth ratio, the shear capacity provided by the diagonal reinforcement and the sub-struts increases with the increase of the span-to-depth ratio of the beam, while the shear capacity provided by the main ECC strut-and-tie decreases.To simulate the behavior of diagonally reinforced engineered cementitious composite(ECC) coupling beam under reversed cyclic loadings, a theoretical model was proposed to predict the skeleton curve of the restoring force of the coupling beam. The proposed model was composed of the main diagonal ECC strut-and-tie, the diagonal reinforcement and the sub-struts based on the softened strut-and-tie model. The restraining effect of stirrups on the compression performance of ECC and the softening effect of ECC under compression and tension were also considered. Based on the proposed model, a formula for calculating the shear capacity of the diagonally reinforced ECC coupling beam was proposed. Eleven diagonally reinforced ECC coupling beam specimens were selected to verify the proposed model. The mean ratio of the calculated shear strength to the measured results is 0.94, and the coefficient of variation is 0.09, showing the good agreement between the calculated values and the experimental results. As for the coupling beams with the small span-to-depth ratio, the shear capacity provided by the diagonal reinforcement and the sub-struts increases with the increase of the span-to-depth ratio of the beam, while the shear capacity provided by the main ECC strut-and-tie decreases.