Behavior of Reinforced Concrete Nuclear Containment Structures Subjected to Tri-Directional Shear Stresses

The unidirectional shear design and behavior of typical reinforced concrete (RC) structures has been extensively studied in the past several decades. Such design requires knowledge of the constitutive behavior of RC elements subjected to a biaxial state of stress. The true behavior of many large complex structures, however, requires knowledge of the constitutive laws of RC elements subjected to a triaxial state of stress. In particular, nuclear containment vessels are subjected to a combination of tangential, peripheral, and radial shear stresses. The goal of this research is to develop new constitutive relations for RC elements, representative of nuclear containment structures, and subjected to tri-directional shear stresses. The paper discusses the development and upgrade of the Universal Panel Tester at the University of Houston to be capable of testing full scale RC panels subjected to tridirectional shear loads. An experimental program to test several RC elements subjected to different combinations of in-plane and out-of-plane shear loads was conducted. The experimental investigation confirmed that there is a strong interaction between the behavior of the shear loads in the in-plane and out-of-plane directions. Based on these findings, a tridirectional shear interaction diagram was constructed.