NONLINEAR ANALYSIS OF PRESTRESSED CONCRETE BEAM BASED ON HYBRID ELEMENT METHOD

A nonlinear hybrid element model has been developed for a prestressed concrete beam, based on co-rotational procedure. A concrete structure was simulated by a layered beam and a prestressed reinforcement was regarded as a truss element with an initial strain in a co-rotational coordinate system, and the nodes of a beam and a truss in the same side were linked by a rigid arm, which can ensure a deformation coordination. The contribution of a prestressed reinforcement for a hybrid element stiffness matrix was acquired by the relation of node displacements and forces in both rigid arm ends, and the hybrid element tangent stiffness for matrix material nonlinearity was derived in a co-rotational coordinate system, through the node displacement and force amount and the incremental relationship between a global coordinate system and a co-rotational coordinate system. The hybrid element geometric and material nonlinearity tangent stiffness in a global coordinate system was proposed. Three examples are solved to verify the reliability and correctness of the proposed hybrid element formulation.