The Earthquake Engineering Online Archive

The development of a mathematical model to predict the flexural response of reinforced concrete beams to cyclic loads, using system identification

Stanton, John F.; McNiven, Hugh D.

UCB/EERC-79/02, Earthquake Engineering Research Center, University of California, Berkeley, 1979-01, 206 pages (555.3/S72/1979)

This report describes the development of a mathematical model to predict the flexural response of reinforced concrete beams to cyclic loads. The objective is to take the first step towards the construction of a model which will predict accurately the nonlinear response of reinforced concrete framed structures when they are subjected to dynamic loads such as seismic disturbances. The model is constructed using system identification. The process consists of selecting a form for the model, and then using suitable mathematical techniques to adjust the numerical coefficients within it so that it reproduces as closely as possible the results of experiments. Beams of several different geometries were tested, allowing the model to be appraised in a variety of configurations. In addition to experimental results and an analytical model form, system identification requires a minimization procedure to find the optimum parameter values. Many algorithms are investigated in order to select one with suitable characteristics. The identification was carried out in several stages. The first was to construct a model for the response of the steel reinforcement using data from axial tests on steel bars. When the steel model was complete, it was incorporated into the global model. The steel parameters were held constant, and the concrete and bond-slip parameters were then identified using the results of tests on laterally loaded reinforced concrete beams. Comparisons were made between the predicted and measured response for a number of different beam configurations.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-79-02.pdf (42 MB)