The Earthquake Engineering Online Archive

Hysteretic behavior of reinforced concrete columns subjected to high axial and cyclic shear forces

Zagajeski, Stanley W.; Bertero, Vitelmo V.; Bouwkamp, Jack G.

UCB/EERC-78/05, Earthquake Engineering Research Center, University of California, Berkeley, 1978-04, 289 pages (515/Z3/1978)

An investigation of the inelastic behavior of short reinforced concrete columns is presented. The results of both experimental and analytical studies are reported. The experimental program was planned to evaluate the hysteretic behavior of short reinforced concrete columns subjected to high axial loads and cyclic shear forces. Column transverse reinforcement was designed with the objective of providing a shear strength, as defined by the UBC 1973 requirements for ductile moment-resisting frames, which would be sufficient to develop the column moment capacity under selected design axial loads. The columns were tested as components of a one-bay, two-story subassemblage of a typical spandrel wall frame. The magnitude of the axial load, the type of transverse reinforcement, and the deformation history were varied to evaluate their influence on column behavior. In the analytical phase of the investigation, a model was formulated to facilitate the analytical study of crack behavior, i.e., crack formation and propagation and the force transfer across cracks, in reinforced concrete members. The analytical model is based on the finite element method of structural analysis. Concrete is modeled as plane stress finite elements and steel reinforcement is modeled as bar elements. The nonlinear material behavior of both steel and concrete is approximated. Concrete cracking is included in the model by a crack line approach. The bond between steel and concrete is included by using different nodes to define the steel and concrete elements and coupling these nodes with dimensionless bond-link elements. The shear forces developed across cracks by aggregate interlock and dowel action of the reinforcement are also modeled by using dimensionless links. The solution strategy developed enables the changes in structure topology, which are required to effect cracking in the model, to be made within the context of an incremental solution process. In its current stage of development, the cracking model has limited application. Suggestions to remedy shortcomings which limit application are made.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-78-05.pdf (113 MB)