Integrated Buildings & Structures

Drawing attached is a church structure. This column alignment is this a good practice. Two storied 8m span 5bays are there. The ground floor is done. Columns are raised for first floor. Theory and practice the difference.  Please clarify my doubt. 

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Alex Thomas R.Eng, M.ASCE
CochinAlexThomasR.Eng, M.ASCEIndia
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Dear Alex, I assumed that you are working with RC. How do you predimension the structural elements? What are the specifications for foundation (soil strength and recommendations from the geotechnical expert)? The plans are feasible but you should check how to solve the beams connecting the 15 m bay (type, materials, reinforcement, shape).
Regards,
AG

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Andres Guzman Ing., M.ASCE
Associate Professor
UNIVERSIDAD DEL NORTE
Barranquilla
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Original Message:
Sent: 8/1/2021 1:07:00 PM
From: Andres Guzman
Subject: RE: Church Structure

Dear Alex, I assumed that you are working with RC. How do you predimension the structural elements? What are the specifications for foundation (soil strength and recommendations from the geotechnical expert)? The plans are feasible but you should check how to solve the beams connecting the 15 m bay (type, materials, reinforcement, shape).
Regards,
AG

------------------------------
Andres Guzman Ing., M.ASCE
Associate Professor
UNIVERSIDAD DEL NORTE
Barranquilla
------------------------------

Dear Alex, columns could be dimensioned with dead and live loads predicted following local regulations and recommendations. Considering the column height, you should deal not only with mechanical strength but also with buckling strength. The critical load for buckling requires a high radius of gyration (Pcr = (pi)^2*E/(k*L/r)^2 ; being r = root(I/A)), so the slenderness ratio (k*L/r) decreases and so, increasing Pcr. 
The best shape for a column should be the one that accomplishes both limits (mechanical strength and buckling strength). You have to consider that no predominant directions for inertia and radius of gyration are preferred (circular column); nevertheless, considering limitations of useful area and forms to construct that column, rectangular shapes or other shapes could be considered. "L", "T", and "I" columns could also be used, but always considering limitations of area (to take advantage of available spaces in the plans).

Regards,
AG

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Andres Guzman Ing., M.ASCE
Associate Professor
UNIVERSIDAD DEL NORTE
Barranquilla
------------------------------

Original Message:
Sent: 08-01-2021 09:17 PM
From: Alex Thomas
Subject: Church Structure

Using thumb rules I have decided the dimensions of the beams and columns

From previous structures it had been detected that if we gave the columns with considerations of least radius of gyration, lead to move the structure to and fro due to live load

Here's an old practice to give corner columns L shaped, shall be giving T shaped columns 

Original Message:
Sent: 8/1/2021 1:07:00 PM
From: Andres Guzman
Subject: RE: Church Structure

Dear Alex, I assumed that you are working with RC. How do you predimension the structural elements? What are the specifications for foundation (soil strength and recommendations from the geotechnical expert)? The plans are feasible but you should check how to solve the beams connecting the 15 m bay (type, materials, reinforcement, shape).
Regards,
AG

------------------------------
Andres Guzman Ing., M.ASCE
Associate Professor
UNIVERSIDAD DEL NORTE
Barranquilla
------------------------------

Hello there,

Have you tried to model the corner columns L-shaped to increase the radius of gyration in each direction?  You also have to check the effects of building torsion on each column i.e. minimum if the structure is symmetrical for EQ and torsion due to critical crosswind.

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Richard Ochotorena P.E., M.ASCE
Architectural Profiles Limited NZ
Hamilton
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Original Message:
Sent: 08-02-2021 08:30 AM
From: Andres Guzman
Subject: Church Structure

Dear Alex, columns could be dimensioned with dead and live loads predicted following local regulations and recommendations. Considering the column height, you should deal not only with mechanical strength but also with buckling strength. The critical load for buckling requires a high radius of gyration (Pcr = (pi)^2*E/(k*L/r)^2 ; being r = root(I/A)), so the slenderness ratio (k*L/r) decreases and so, increasing Pcr.
The best shape for a column should be the one that accomplishes both limits (mechanical strength and buckling strength). You have to consider that no predominant directions for inertia and radius of gyration are preferred (circular column); nevertheless, considering limitations of useful area and forms to construct that column, rectangular shapes or other shapes could be considered. "L", "T", and "I" columns could also be used, but always considering limitations of area (to take advantage of available spaces in the plans).

Regards,
AG

------------------------------
Andres Guzman Ing., M.ASCE
Associate Professor
UNIVERSIDAD DEL NORTE
Barranquilla
------------------------------


Original Message:
Sent: 08-01-2021 09:17 PM
From: Alex Thomas
Subject: Church Structure

Using thumb rules I have decided the dimensions of the beams and columns

From previous structures it had been detected that if we gave the columns with considerations of least radius of gyration, lead to move the structure to and fro due to live load

Here's an old practice to give corner columns L shaped, shall be giving T shaped columns 

Original Message:
Sent: 8/1/2021 1:07:00 PM
From: Andres Guzman
Subject: RE: Church Structure

Dear Alex, I assumed that you are working with RC. How do you predimension the structural elements? What are the specifications for foundation (soil strength and recommendations from the geotechnical expert)? The plans are feasible but you should check how to solve the beams connecting the 15 m bay (type, materials, reinforcement, shape).
Regards,
AG

------------------------------
Andres Guzman Ing., M.ASCE
Associate Professor
UNIVERSIDAD DEL NORTE
Barranquilla

Keep in mind that the highest design-wind-load conditions typically occur at the corners.  Since the design does not appear to have any structural columns in the end walls, the corner columns may need to be strengthened to provide adequate torque resistance.  If there is an option to add structural columns to the end walls, even if they are only a few feet in-board of the corners that could provide significant structural benefits.  Exterior buttresses might be another option.

Your description did not discuss the first-floor structural design.  Will it be designed as a moment-resisting rigid diaphragm?  If so, it can contribute to the torque resistance, but the transfer of those forces into the columns needs to be accounted for in the column sizing, bracing, connections and anchoring. 

If seismic loads are a concern, the most highly loaded columns may be different than those identified by the wind-load analysis.

Bruce Clarke, P.E. M.ASCE, SECB
BH Clarke Engineering, LLC

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Bruce Clarke P.E., M.ASCE
Owner
BH Clarke Engineering, LLC
Belmont MI
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