Seismic Performance And Design Method Of Cross-laminated Bamboo Rocking Wall

The latest researches in structural engineering have focused on the characteristics of resilience of the building,while the use of environmental-friendly material is also the tendency of the development of civil engineering.A novel self-centering rocking wall structure with the green material bamboo,which is called cross-laminated bamboo(CLB)rocking wall,has been the new research direction of bamboo structures.The test of the CLB rocking wall was finished but the material test of CLB is not complete,and the research on the analytical model and numerical model of CLB is scanty now.Therefore,the analytical and numerical studies of CLB rocking wall are carried out in this paper,and the design procedure is proposed.The seismic performance of the CLB rocking wall is further studied and the engineering practice of the CLB rocking wall will be promoted based on the achievements of this paper.The major research work and conclusion of this paper are as follows:(1)The rolling shear tests of the CLB are conducted and the rolling shear strength and modulus are obtained as material parameters for the development of CLB analytical and numerical models.The three-point bending test and planar shear test are carried out and the finite element models for rolling shear tests are developed in ABAQUS to explore the rolling shear failure modes of CLB.The test results indicate that the rolling shear strength of CLB is much higher than the rolling shear strength of cross-laminated timber(CLT).The rolling shear failure modes of the finite element models are similar with the tests while the bearing capacity of finite element models fits well with tests,which demonstrate the accuracy of the model.(2)The analytical model of the CLB rocking wall is developed based on the rocking wall test.The limit states of the CLB rocking wall are proposed based on the study of the behavior of the CLB rocking wall under lateral load.The calculation methods of the shear force and displacement of each limit state are carried out and the envelop curve of the CLB rocking wall can be obtained.Then the analytical model is verified by the test results.(3)The numerical model of CLB rocking wall is developed based on ABAQUS.The results of the numerical model are verified by the test results.The parametric study is conducted after the verification of the model.The parameters include the initial prestress of the rocking wall,the cross-sectional area of the posttensioned rebars,the aspect ratio of the wall panel,and the friction force of the friction dampers.The stiffness,energy dissipation capacity,and self-centering capacity of the CLB rocking wall are studied.The parametric study shows that the stiffness of the CLB rocking wall depends on the cross-sectional area of the posttensioned rebars,and the stiffness of rocking wall increases with the increase of the cross-sectional area of the rebar.The energy dissipation capacity of the rocking wall can be largely improved by the friction force of the friction dampers,while the self-centering capacity of the rocking wall decreases with the increase of the friction force.(4)The displacement-based design method(DBD)of multi-story CLB rocking wall structures is proposed based on the analytical and numerical model.The key components of the rocking wall including prestressed rebars and friction dampers are designed through the DBD to satisfy the story drift limits.Then the finished three-story CLT shear wall structure(X-Lam)is transformed into three types of structure: the CLB shear wall structure(X-Lam B),the CLB shear wall and multi-segmentation rocking wall structure(X-Lam BR1),and the CLB shear wall and single-segmentation rocking wall structure(X-Lam BR2).The X-Lam BR1 and X-Lam BR2 are selected as the prototype for the design of CLB rocking wall.The time history analysis is conducted on the finite element model of X-Lam BR1 and X-Lam BR2,respectively,to verify the DBD.The time history analyses are conducted on X-Lam B,X-Lam BR1,and X-Lam BR2 to compare the seismic performances of the three structures.The results show that the X-Lam BR1 and X-Lam BR2 have smaller story drift,residual story drift,and maximum acceleration than X-Lam B.The fragility analyses are conducted on X-Lam B and X-Lam BR1,and the results show that the X-Lam BR1 has better seismic performance under the maximum considered earthquake.