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Flaring of Shear walls and Columns

 
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Sathish_Pandurangan
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Joined: 10 Mar 2021
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PostPosted: Wed Mar 10, 2021 12:35 pm    Post subject: Flaring of Shear walls and Columns Reply with quote

Hello,

The project which i am handling presently have restrictions in length of columns due to building line. So that I decided to flare the columns above ground floor. Is there any limit for the flaring length? I heard there is some percentage limit to the total length of column. Please advise.

Thanks

Sathish
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Dr. N. Subramanian
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Joined: 21 Feb 2008
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Location: Gaithersburg, MD, U.S.A.

PostPosted: Wed Mar 10, 2021 7:03 pm    Post subject: Re: Flaring of Shear walls and Columns Reply with quote

Dear Er Sathish,

Although flared columns are not common in buildings they have been used in bridges. Flared shaped columns with two types of one-way and two-way flares have been used. Besides the architectural inclination, one-way flared columns were commonly used in post-1970 bridges (around 42% of California box-girder bridges) to provide more support to the cap beam under eccentric live load.

Flared columns are constructed in two different ways by either integrating them to the superstructure (i.e. connected) or connecting them to the superstructure with a gap in between (i.e. isolated).
The latter type is typically used in constructing bridges designed after 1990.

Sanchez, et al. (1997) conducted experimental studies on flared columns and concluded that the seismic performance of the isolated flares is similar to the prismatic columns. Soleimani et al., 2017 found that the  bridges including flared columns show higher vulnerability than the bridges including prismatic columns.

I have included typical sizes used in Ref. 4

Best wishes
Subramanian

References:
1. Sanchez, A. V., M. Priestley and F. Seible, "Seismic performance of flared bridge columns," US Santiago test report, 1997.
2. Nada, H., D. Sanders and M. S. Saiidi, "Seismic performance of RC bridge frames with architectural-flared columns (No. CCEER 03-03),"
Center for Earthquake Engineering Research, University of Nevada, 2003.
3. Wehbe,N.I., M. S. Saiidi and D. H. Sanders, "Effects of confinement and flares on the seismic performance of reinforced concrete bridge
columns," (No. RDT-01-004, CCEER-97-2), 1997.
4. Saiidi,M. S., J. Mortensen, and F.Martinovic, Analysis and Retrofit of Fixed Flared Columns with Glass Fiber-Reinforced Plastic Jacketing, Report No: RDT 01-027, Nevada Department of Transportation, 2001, 55 pp.
5. Soleimani, F., S. Mangalathu, and R. DesRoches, "Seismic Resilience of Concrete Bridges with Flared Columns", Procedia Engineering 199 (2017) 3065–3070


Sathish_Pandurangan wrote:
Hello,

The project which i am handling presently have restrictions in length of columns due to building line. So that I decided to flare the columns above ground floor. Is there any limit for the flaring length? I heard there is some percentage limit to the total length of column. Please advise.

Thanks

Sathish



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vikram.jeet
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PostPosted: Sat Mar 27, 2021 5:35 pm    Post subject: Reply with quote

Flaring outside at smaller angle (keeping inside col line vertical) can be done but it would cause additional moments in gf col due to ecc and needs to be accounted for in col design.  Not done any flared col , hence my suggestion is just from logical point that a flare of 1:7  to 1:5 can be given minm. Also it shall go with front elevation conceived by architect.

Vikram.jeet
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