Advanced analysis of hybrid frame structures by refined plastic-hinge approach
S.L. CHAN, S.W. LIU, Y.P. LIU
Department of Civil and Structural Engineering, The
Hybrid frames composed of steel, concrete and composite members are widely used to-date due to their structural efficiency, especially in high-rise buildings. The design of this form of structures is inconvenient as it needs several separate design codes for steel, concrete and composite elements. This paper proposes a nonlinear design method which only requires section capacity check without the use of different codes for the hybrid frame structures. By using the pointwise-equilibrium-polynomial (PEP) element allowing for initial imperfection in conjunction with a robust nonlinear incremental-iterative procedure, the second-order effects of individual members and the structural system can be modeled. The sectional fibre approach is used to determine the section capacity of arbitrary shape reinforced concrete or composite member subjected to axial force and biaxial bending. To fulfil the requirement of seismic design, progressive collapse analysis and advanced analysis, the refined plastic-hinge approach is utilized to model the plastic behaviour with strain-hardening effect. Once the initial and full yield surfaces are determined, the gradual yielding is simulated. Two examples are employed to demonstrate the validity and accuracy of the proposed method.