Stochastic Nonlinear Behavior of Reinforced Concrete Frames. I: Experimental Investigation

Abstract

This paper reports a systematic experimental investigation into the stochastic nonlinearities inherent in reinforced concrete (RC) frames. A series of specimen tests is conducted with a static monotonic lateral loading regime. Eight half-scale RC model frames with one story and two spans are designed and constructed in the same condition; specifically, the materials (both concrete and reinforcement bars) used in the frames are derived from the same batch, and the same testing program is performed during the experiments. A newly-designed force transducer is applied in the test to carry out comprehensive measurements of axial force, shear force, and bending moment at the bottom section of each column. Although the physical properties of the frames are apparently the same, test results indicate that the internal forces of the columns show inevitable fluctuations. A conspicuous coupling effect between nonlinearity and randomness, which are inherent in the structure, is exposed. Randomness of materials (particularly concrete) has an influence on the initial damage distribution and the subsequent damage evolution of the structure. Thus, it is concluded that the coupling mechanism between randomness and nonlinearity of RC structures should be appropriately considered in design and analysis to reproduce the realistic response of concrete structures.