Q & A

Questions on the prediction can be submitted to Vesna Terzic and selected questions with answers will be posted here.

Question 1:  What are the effective heights of the actuators from the base of the column?
(Date: 7/26/2021)

Answer: The requested information is included in the revised version of the "Test Description, Material Properties, and Drawings" file under "Given Information" page (see Figure 2). However, the actuator locations should not matter, because they are coordinated to fix the top of the column against rotation.

Question 2:  Was the specimen cast in a single phase or different phases? (Date: 8/3/2021)

Answer: The specimen was cast in a single placement in the horizontal position.

Question 3:  What is the modulus of elasticity of steel rebars and the strain of steel at the strain hardening? (Date: 8/3/2021)

Answer: These specific data are not available from the tension tests of reinforcing bars. However, for Grade 60 bars, we recommend that you use a modulus of elasticity of 29,000 ksi and strain of 4 to 6 times yield strain at the strain-hardening.

Question 4:  Are actuators supported by the column? If they are, what is the tributary weight of two actuators on the column? (Date: 8/05/2021)

Answer: The actuators and loading beams are not supported by the column (see the picture). The steel loading fixtures attached to the upper concrete column block weigh approximately 2200 lbs total (1100 lbs each), and each has a vertically slotted hole in the greased knife plate that connects to the loading beams. This essentially eliminates any transfer of vertical load between the loading beams and the test specimen.

Question 5:  What length should be used to compute the drift ratio? Is it the clear length 2667mm? (Date: 8/5/2021)

Answer: Yes, the clear length of the column [2667 mm (8'-9")] shall be used to compute the drift ratio.

Question 6:  Was the column top allowed to move axially (in the vertical direction)?
(Date: 8/5/2021)

Answer: Yes, the column was free to move axially. The steel loading fixtures attached to the upper concrete column block had a vertically slotted hole in the greased knife plate that connects to the loading beams (see Figure 2 of the Test Description file).

Question 7:  During testing was there any rotation at the top or at the base of the column?
(Date: 8/10/2021)

Answer: The rotation of the top and the bottom end blocks of the column was measured during the test, and rotation was negligible.

Question 8:  How are the (8) #10 vertical bars terminated at the top and bottom?
(Date: 8/10/2021)

Answer: The #10 bars are straight at the upper (78-inch) end block, and they have 90-degree standard hooks at the bottom (48-inch) end block.

Question 9:  What is the aggregate size used in the column for the blind prediction contest?
(Date: 8/16/2021)

Answer: The concrete mix had 1” coarse aggregate.