109- مقاله انگلیسی- Application of a Confined Concrete Model to
مقاله انگلیسی- Application of a Confined Concrete Model to
شماره فایل : 109
Application of a Confined Concrete Model to Passively Confined Concrete Columns
Introduction:
Reinforced concrete bridge columns are provided with transverse confinement in the form of hoop or spirals for new structures and steel or carbon fiber composite shells for older existing structures, allowing ductile plastic hinges to form at the column ends in response to moderate to large seismic events. Concrete compressive strength and strain capacity increase with increasing confining stress, with the result that the force-displacement response and displacement ductility of the structure are often directly related to the level of confining stresses provided in the critical plastic hinge regions. In relatively simple moment-curvature analysis, the confinement level is typically calculated, prior to the analysis, based on equilibrium of the yielded transverse reinforcement against the concrete. This is a reasonable approach when the confining steel is expected to yield at an early stage, providing approximately constant pressure throughout the loading. However, if the confining pressure is expected to change significantly throughout the loading, as in the case of a concrete filled carbon fiber shell column, a more advanced methodology is required which depends on the current stress state.