Inelastic modeling of reinforcing bars and blind analysis of the benchmark tests on beamcolumn joint

Student: Wei Yu
Supervisors: Dr. Rui Pinho

ABSTRACT

The most challenging issue for the seismic design of R/C beam-column joints is the lack of theoretical model. Non-linear cyclic behaviour of reinforced concrete beam-column joint sub-assemblage is complex and known to be sensitive to many factors interacting each other, including, flexural action of beams and columns, shear behaviour in beam-column joint, bond and anchorage of longitude bars and joint concrete confinement. So a model is needed in which the material non-linearity is modeled appropriately with all-around ability with less arbitrary parameters as much as possible. The behaviour of reinforcing steel may affect the response of R/C beam-column joints as much as to R/C structural  elements subject to earthquake loading. Thus, it is necessary to develop an analytical model that predicts the fundamental characteristics of steel within a range of loading that is appropriate for these structural systems. Typical load histories for reinforcing steel follow from consideration of the observed response of reinforced concrete structural elements. Characteristics of steel response are established through laboratory testing of steel coupons. Previous research provides theories and techniques for development of an analytical model that predicts steel response. Experimental data provide information for final calibration and refinement of the proposed models. Two sophisticated models for defining cyclic behavior of reinforcing steel are first introduced in this dissertation work, a simplified beam-column joint model is subsequently presented. Analytical models proposed for use in previous investigations are also presented. Blind analysis of the benchmark tests on R/C beam-column joint are finally carried out employing the adopted reinforcing steel and beam-column joint model. Additional comparison is also made between results with using different reinforcing steel models in the blind analysis to show its importance to cyclic behavior of R/C beam-column joints.

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