RAJSHARN
Structural
- Jun 28, 2017
- 1
Is anyone able to provide their interpretation to these 2 clauses from NZS3101 regarding the beam-column joint?
Clause 15.2.1 - "Provisions of this section apply to the design of beam-column joints subject to shear where a minimum of 70 % of the top beam reinforcement and 70 % of the bottom beam reinforcement contributing to nominal flexural strength either pass through the column or are anchored in the column. Where this does not apply, design shall be based on strut and tie analysis."
Clause 15.3.6.2 (b) - "In external beam column joints where the beam reinforcement is terminated by 90o hooks as specified
in 8.6.12.6, joint shear reinforcement equal to or greater than Ajh =0.25 Vjh shall enclose the vertical φ fyh leg of the hooked bars and the longitudinal column reinforcement. The criteria applies separately to both positive and negative terminating beam reinforcement."
Suppose I have single level concrete frame, where the beam requires 6 rebars at midspan and only 3 rebars at the end region where it connects to the column.
Firstly, do I need to consider 70% of the 6 bars or 70% of 3 bars to continue into the joint? If in the end region let's say I provide 6 bars, although I only require 3 bars, do I then need to continue 70% of 6 bars or 70% of 3 bars?
Secondly, in a circular column, unless the column is relatively bigger, it will be difficult to comply with clause 15.3.6.2 (b) as not all beam bars can be anchored into the reo cage, would you agree?
Clause 15.2.1 - "Provisions of this section apply to the design of beam-column joints subject to shear where a minimum of 70 % of the top beam reinforcement and 70 % of the bottom beam reinforcement contributing to nominal flexural strength either pass through the column or are anchored in the column. Where this does not apply, design shall be based on strut and tie analysis."
Clause 15.3.6.2 (b) - "In external beam column joints where the beam reinforcement is terminated by 90o hooks as specified
in 8.6.12.6, joint shear reinforcement equal to or greater than Ajh =0.25 Vjh shall enclose the vertical φ fyh leg of the hooked bars and the longitudinal column reinforcement. The criteria applies separately to both positive and negative terminating beam reinforcement."
Suppose I have single level concrete frame, where the beam requires 6 rebars at midspan and only 3 rebars at the end region where it connects to the column.
Firstly, do I need to consider 70% of the 6 bars or 70% of 3 bars to continue into the joint? If in the end region let's say I provide 6 bars, although I only require 3 bars, do I then need to continue 70% of 6 bars or 70% of 3 bars?
Secondly, in a circular column, unless the column is relatively bigger, it will be difficult to comply with clause 15.3.6.2 (b) as not all beam bars can be anchored into the reo cage, would you agree?
