Please note, the reduction factor, Ri, is intended to correct the Internal Pressure Coefficient, GCpi, as a function of Total Area of openings, Aog, and unpartitioned internal volume, Vi, for partially enclosure buildings.

If you evaluate the

Lim Ri(Vi, Aog), when Aog → ꝏ, then Ri ≈ 1.0

Lim Ri(Vi, Aog), when Aog → 0, then Ri ≈ 0.5

Thus, for very large area of openings, Ri will be closer to 1.0

And for very reduced area of openings, Ri will be closer to 0.5

You probably need to verify the deduction of your Vi, Aog, and the enclosure classification of your building.

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Gustavo Escorcia Ing., P.E., M.ASCE

Structural Engineer

STV / Ralph Whitehead and Associates

North Chesterfield VA

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Original Message:

Sent: 03-20-2023 11:12 AM

From: Mohammed Awez

Subject: REDUCTION FACTOR Ri FOR INTERNAL PRESSURE

Thanks Gustavo Noted !

Infact 2016 and 2022 have shown 22800

However I am having merely no reduction if apply the values as per 22800 even my unpartioned volume quite huge? Will this equation ever gives a reduction ?

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Mohammed Awez Aff.M.ASCE

Design Engineer

DUBAI

Original Message:

Sent: 03-20-2023 09:35 AM

From: Gustavo Escorcia

Subject: REDUCTION FACTOR Ri FOR INTERNAL PRESSURE

Mohammed,<o:p></o:p>

<o:p> </o:p>

The denominator in the square root of the Reduction Factor equation for Large Volume Building is twenty-two thousand eight hundred (22,800) ft * Aog (sf), as is shown on ASCE 7-05 equation 6-16. <o:p></o:p>

<o:p> </o:p>

Please try to use the third printing of ASCE 7-10, which incorporates errata identified through March 15, 2013. In this third printing of the standard, the equation for Reduction factor for Large Volume Buildings (Eq. 26.11-1), matches the one shown on ASCE 7-05 (6-16).<o:p></o:p>

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Gustavo Escorcia Ing., P.E., M.ASCE

Structural Engineer

STV / Ralph Whitehead and Associates

North Chesterfield VA

Original Message:

Sent: 03-18-2023 04:04 AM

From: Mohammed Awez

Subject: REDUCTION FACTOR Ri FOR INTERNAL PRESSURE

I have a confusion/doubt over the Reduction factor Ri equation shown in ASCE7-05 vs ASCE7-10.

ASCE7-05 the equation 6-16 shows as 22,800Aog there is comma between 22 and 8 however the same in ASCE7-10 equation 26.11-1 there is dot between 22 and 8.

I was designing the building with large unpartioned volumne , building under design unpartioned volume is Vi =233279633 ft3 and Aog = 281525 ft2.

when i apply ASCE7-05 I am mererly getting any reduction in the internal pressure , however same if i apply with ASCE7-10 I am having reduction as 0.32 from 0.55.

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Mohammed Awez Aff.M.ASCE

Design Engineer

DUBAI

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