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Report - PEER - University of California, Berkeley

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B(Beam) mode J(Joint) mode(a) Loading and deformation in closing directionB(Beam) mode J(Joint) mode(b) Loading and deformation in opening directionFigure 3. B(Beam)-mode and J(Joint)-mode for knee joints..3. APPLICATION TO KNEE JOINTTo demonstrate how the theory works for the prediction <strong>of</strong> the strength and type <strong>of</strong>failure, an example <strong>of</strong> application to a very simple R/C knee joint is examined. Due tothe limit <strong>of</strong> the space, the procedure <strong>of</strong> analysis is briefly introduced here. Detailedexplanation is available in the reference (Shin and Shiohara 2004).3.1 Geometry and NotationsFigure 4 shows the geometry <strong>of</strong> the symmetric knee joint. To simplify the solution, thesubstructure are assumed symmetric and the joint panel is square <strong>of</strong> D. The thickness<strong>of</strong> column and joint are assumed to be t. The distance between the center <strong>of</strong> the jointpanel to the contra flexural points in the beam or column is L. External loads areapplied at the contra flexural points in the direction <strong>of</strong> straight line connecting the twocontra flexural points. As a result, column shear V and column axial force N (=V) actson the contra flexural points on the column.3.2 Notations for Internal ForcesFigures. 4(d) to 4(g) show the notations defining the set <strong>of</strong> internal forces at the criticalsections for the J-mode <strong>of</strong> knee joints under loading in closing direction and openingdirection respectively. The notations T 1 , T 2 , T 3 , and T 4 represent the resultanttensile forces in longitudinal bars, while C 1 C 2 and C 3 represent the resultant compressiveforces on the concrete boundaries when it subjected to closing force, and C 4 C 5and C 6 represent the resultant compressive forces in concrete when it is subject to loadin opening direction. The values <strong>of</strong> C 1 and C 2 equal to the x component <strong>of</strong> compressiveresultant in concrete. So the direction <strong>of</strong> concrete principle stress is normal to thecritical section. The forces T 2 , and T 3 are common variables for both B-mode and J-mode. All <strong>of</strong> the compressive stress in concrete on the critical section is assumed to be460

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