CIVE 421 Other, Spring 2008

FACULTY OF G & AR TECTURE ‘CE-083 CONCRETE I QUIZ 1 (2 HOURS), April 27,1999 {OPEN BOOK) . In the design of continuous beams, why are the negative moments resulting from elastic analysis reduced to the face of the supporting columns. In the analysis of one-way ribbed slabs, would you reduce the negative moments at the center of the supporting beams to the face of the beams! Sketch the nominal axial load-moment interaction diagram for a reinforced concrete column. Corresponding to this diagram, sketch the expected axial load-ultimate curvature diagram. #o |, 20 | or Longitudinal Reinforcement = 84625" f= 280 kp/em’, fy = 4200 kgicm*, and E, = 29 x 10° psi ifs 2. Locate the plastic centroid. ‘Use a strain compatibility analysis to determine the nominal axial load end nominal moment capacities at balanced conditions. What is the curvature at balanced conditions. Add more necessary transverse reinforcement (ties) for adequate confinement. Show the required ties on the question shect. Design a square reinforced concrete column to resist simaltaneously a factored axial load of 200 Ton and two factored moments: Myx = 60 T-m and Myy = 40 T-m. Use a longitudinal reinforcement ratio of 2.5 percent. Use Bresler’s reciprocal load equation and ACI column strength interaction diagrams. f, = 280 kg/cm? (4000 psi) and fy = 4200 kg/cm”. Show a sketch of the designed section. \P — Column = (60 x 60) W P: Dead Load = 150 Tons Live Load = 100 Tons 4.5m W = Short term wind load = 10 Tons fo = 211 kg/om’, fy = 4200 kg/em? ‘ I; The (60x60) tied column shown above is unbraced. Determine the required longitudinal reinforcement ratio for the column. Hint: Check two load cases. For the gravity load case, assume no sidesway and k = 0.7. For_the gravity plus wind load case, the column acts as a cantilever with k = 2.