engleski

Large displacement model of R/C space frames

The large displacement model of the material and geometrically nonlinear three-dimensional (3D) reinforced concrete frames follows incrementally small displacement theory presented and a conclusion about the quasi tangential stiffness matrix. The global 3D reinforced concrete structure consists of the beam-column straight members, each of them discretized by a few FE. Updating the large translation displacement from increment to increment follows from simple summarising of the incremental translation displacement vector. Updating the large rotations is related to the FE and corresponds to the rigid body incremental rotations what is an approximate solution. This approximation shall be numerically tolerable if a length of the FE is small enough. The geometrical updating of the predicted load and the internal forces depends on the differences of the tangent stiffness matrix between two increments. The mapping of the complete predicted load over the actual tangent stiffness matrix results in the new configuration called null configuration. In the same null configuration the predict load over new tangent stiffness matrix maps a new distribution of the internal force and strike out the additional displacement. The incremental loading, either follower or gravitational, follows the usual procedure.

R/C space frame ; large displacement ; comparative body ; null configuration

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