Mixed Formulation for Composite and RC Frame Element with Bond-Slip

May 30, 2010
Publication: 19th Analysis and Computation Specialty Conference (part of ASCE Structures Congress 2010) p 516-526
Author(s): Lee, Chin-Long Filippou F. C.

Abstract: In structural elements made up of two or more materials, such as steel-concrete composite beams and columns, reinforced and prestressed concrete elements, and members with FRP reinforcement, the relative slip between material components plays an important role in the strength and energy dissipation capacity of the composite element. Frame finite elements proposed to date that include the relative slip between components are limited to 2d members and, furthermore, lack a framework that permits large displacement cyclic analysis of structures. This paper formulates a new 3d frame element for the inelastic response of structural members that includes the relative slip among components. The formulation is based on the three field Hu-Washizu variational principle with the interface slip among components as one of the independent variables. The proposed element is validated with two correlation studies. They showcase the advantages of the proposed formulation which allows for the relative slipdiscontinuity at the interface between the element and the joint or foundation.