"Nonlinear Static and Dynamic Analysis of Reinforced Concrete Subassemblages"
by F.C. Filippou, A. D'Ambrisi and A. Issa

Abstract: This study is devoted to the development of improved models and methods for predicting the nonlinear static and dynamic response of reinforced concrete frames. In this respect it is a continuation of the work presented in an earlier study (Filippou and Issa, 1988).

To achieve the general objective new models for reinforced concrete girders were proposed in the earlier study (Filippou and Issa, 1988). Each girder was decomposed into a number of subelements which were connected in series. Each subelement describes a different source of inelastic deformation and energy dissipation in reinforced concrete members. Three subelements were developed in the earlier study: (a) an elastic subelement which models the flexural behavior of the frame member before yielding of the reinforcement; (b) a spread plastic subelement which describes the inelastic flexural behavior of the reinforced concrete member and accounts for the gradual spread of inelastic deformation at the member ends; and (c) a joint subelement modeling the fixed-end rotation that arises at the beam-column interface due to bond deterioration and slippage of reinforcing bars along the anchorage in the joint.

The present study introduces several new subelements. The first is a shear subelement which describes the deformation due to shear and, in particular, due to the shear sliding in the inelastic regions of reinforced concrete members, and complements the list of girder subelements of the earlier study. The other subelements refer to the hysteretic behavior of RC columns and are extensions of the corresponding girder subelements to account for the effect of axial load on the flexural and shear behavior of the member.

The proposed reinforced concrete frame models are implemented in a special purpose computer program for the nonlinear static and dynamic analysis of reinforced concrete frames. A nonlinear solution method which accounts for the possible unbalance of internal forces between the different subelements during the load step and an algorithm for the efficient numerical implementation of this solution strategy was already proposed in the earlier study. This procedure is now extended to include the additional subelements, but, more importantly, to address time varying loads due to ground acceleration. Implementation issues under static and dynamic loading conditions are also addressed in the present study.

The analytical results are compared with experimental information from beam-column subassemblages under cyclic deformation reversals. Only studies related to the effects of shear and axial load are discussed. These correlation studies complement those presented earlier by Filippou and Issa (1988).

The ability of the proposed models to describe the dynamic response of frame structures that are excited by ground accelerations is evaluated by comparing the analytical results with experimental evidence from a two story one bay reinforced concrete frame that was tested on the shaking table. The effect of bond slip on the local and global dynamic response of the structure is evaluated. The results of the proposed model are compared with those of the widely used one component model in order to assess the ability of the latter to determine the local and global response of reinforced concrete frames.

If you are interested in a copy of this report, please contact the EERC Library at eerclib@shake.berkeley.edu or send e-mail to Professor Filippou