Lecture 29 Reinforced Columns

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Lecture 29 - Reinforced Columns

• November 8, 2002
• CVEN 444

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Lecture Goals

• Columns
• Short Column Design
• Interaction Diagrams

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Example Column design using Interaction Diagrams
Determine the tension and compression
reinforcement for a 16 in x 24 in. rectangular
tied column to support Pu 840 k and Mu 420
k-ft. Use fc 4 ksi and fy 60 ksi. Using the
interaction diagram.
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Example Interaction Diagrams
Compute the initial components
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Example Interaction Diagrams
Compute the initial components
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Example Interaction Diagrams
Compute the coefficients of the column
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Example Interaction Diagrams
Using an interaction diagram, B-13
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Example Interaction Diagrams
Using an interaction diagram, B-14
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Example Interaction Diagrams
Using linear interpolation to find the r of the
column
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Example Interaction Diagrams
Determine the amount of steel required Select
the steel for the column, using 11 bars
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Example Interaction Diagrams
The areas of the steel The loading on the
column
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Example Interaction Diagrams
The compression components are
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Example Interaction Diagrams
The tension component is
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Example Interaction Diagrams
Take the moment about the tension steel
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Example Interaction Diagrams
The first equation related to Pn
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Example Interaction Diagrams
The second equation comes from the equilibrium
equation and substitute in for Pn
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Example Interaction Diagrams
Substitute the relationship of c for the stress
in the steel. The problem is now a cubic
solution c fs RHS 15
in. 37.7 -10.38 19 in. 11.45
2.64 19.5 in. 8.92 4.63 20.0 in.
6.52 6.70 19.98 in. 6.62 6.62
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Example Interaction Diagrams
Compute Pn Compute Mn about the center
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Example Interaction Diagrams
Compute Mn about the center
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Example Interaction Diagrams
Check that Mn is greater than the required Mu
Check the Pn is greater than the required Pu
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Example Interaction Diagrams
Determine the tie spacing using 4 bars
Use 16 in.
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Homework
Due 11/15/02 Problem 9.6, part a using at least
10 points Using the interaction diagram, design a
column with h 28 in., g 0.84 and b 18 in.,
PD 240 k and PL 480 k and Mu 704 k-ft.
Determine the amount of reinforcement and type of
ties and their spacing for fy 60 ksi and fc
5 ksi
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Project
Part A3 Due 11/18/02 Part B1 Due 11/22/02
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Exam 2
November ? (19 or 26)