Public defence in civil engineering, Jinming Zeng, M.Sc.
When
Where
Numerical and analytical methods to investigate the load-bearing strength of joints in slim-floor composite frame
The load-bearing strength of double-side joints between a hat-shaped WQ-beam and a circular concrete filled composite column is investigated by using experimental, numerical and analytical methods. 3D finite element models considering both material and geometrical nonlinearities are created for the joint and validated by the test results. The steel is assumed to be ideal elastic-plastic or with isotropic hardening. The limit load of joint is determined by both strain and deformation-limit criteria. According to the strain criterion, the plastic strain of 10% reasonably predicts the limit load of the joint. For the design use, the deformation limit of 2% of flange width is recommended.
To predict the limit load of the joint, four-hinge yield line mechanisms are developed. Due to the asymmetric nature of plastic collapse, two two-parameter models are established. One is based on pure bending at the hinges, and the other also considers the axial force. Linear and nonlinear analyses for rotations are performed for each model. The comparisons between analytical and numerical results show that all analytical models predict the limit load of the joint at the plastic strain of 10% well. Since the console can withstand large strain, the analytical models with pure bending together with an existing method are further developed to include the role of the strain hardening. The result shows that the analytical models with linear strain hardening provide satisfied prediction. A general equation is proposed to predict the limit load of joint. The studies show that the model considering pure bending together with linear presentation of rotations is simple to use but can be slightly conservative, whereas the model including the normal force, better predicts the load-bearing capacity of the joint. Compared to the method provided in design code as EN 1993-1-8, the proposed equation predicts the higher load-bearing capacity, leading to a more economical design in practice particularly if larger indentation is allowed.
Opponent: Professor, PhD Cedric D’Mello, City, University of London, United Kingdom
Custos: Professor Juha Paavola, Aalto University School of Engineering, Department of Civil Engineering
Contact information of the doctoral student: Jinming Zeng, jinming.zeng@aalto.fi
The public defence will be organised on campus (auditorium R1, Rakentajanaukio 4)
The thesis is publicly displayed 10 days before the defence in the publication archive Aaltodoc of Aalto University.