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DSM Calculator

The document summarizes beam and column strength calculations for a structural member using the Direct Strength Method (DSM). For the beam, the nominal flexural strength is controlled by distortional buckling. For the column, the nominal axial strength is controlled by local-global buckling. A beam-column calculation is then performed using the DSM results and shows the member satisfies the applicable strength criteria.

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Gaurav Agarwal
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1K views4 pages

DSM Calculator

The document summarizes beam and column strength calculations for a structural member using the Direct Strength Method (DSM). For the beam, the nominal flexural strength is controlled by distortional buckling. For the column, the nominal axial strength is controlled by local-global buckling. A beam-column calculation is then performed using the DSM results and shows the member satisfies the applicable strength criteria.

Uploaded by

Gaurav Agarwal
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as XLS, PDF, TXT or read online on Scribd
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Date: July 19th 2006 Name: BWS

Beam strength calculations using the Direct Strength Method of Appendix 1

Given: Notes: XXXXZXXX Example DSM Beam Calculation (job1.mat)


My = 100 kip-in
Mcrℓ/My = 0.5 Mcrℓ = 50 kip-in
Mcrd/My = 0.5 Mcrd = 50 kip-in
Mcre/My = 1.3 Mcre = 130 kip-in

Lateral-torsional buckling nominal flexural strength per DSM 1.2.2.1

Mne = 87.369 kip-in


Local buckling nominal flexural strength per DSM 1.2.2.2

lℓ = 1.32 (local-global slenderness)


Mnℓ = 61.5 kip-in (local-global interaction reduction)
Distortional buckling nominal flexural strength per DSM 1.2.2.3

ld = 1.41 (distortional slenderness)


Mnd = 59.7 kip-in (distortional reduction)
Nominal flexural strength of the beam per DSM 1.2.2

Mn = 59.71 kip-in (distortional controls)

Does this section meet the prequalified limits of DSM Section 1.1.1.2? (Y/N) Y

f= 0.9 design strength fMn = 53.74 kip-in


W= 1.67 allowable design strength Mn/W = 35.75 kip-in
Date: July 19th 2006 Name: BWS

Column strength calculations using the Direct Strength Method of Appendix 1

Given: Notes: XXXXZXXX Example DSM Column Calculation (job1.mat)


Py = 100 kip
Pcrℓ/Py = 0.5 Pcrℓ = 50 kip
Pcrd/Py = 0.5 Pcrd = 50 kip
Pcre/Py = 1.3 Pcre = 130 kip

Flexural, Torsional, or Torsional-flexural Buckling nominal axial strength per DSM 1.2.1.1

lc = 0.877
Pne =72.473 kip
Local buckling nominal axial strength per DSM 1.2.1.2

lℓ = 1.20 (local-global slenderness)


Pnℓ = 54.4 kip (local-global interaction reduction)
Distortional buckling nominal axial strength per DSM 1.2.1.3

ld = 1.41 (distortional slenderness)


Pnd = 55.1 kip (distortional reduction)
Nominal axial strength of the column per DSM 1.2.1

Pn = 54.40 kip (local-global controls)

Does this section meet the prequalified limits of DSM Section 1.1.1.1? (Y/N) Y

f= 0.85 design strength fPn = 46.24 kip


W= 1.8 allowable design strength Pn/W = 30.22 kip
Date: July 19th 2006 Name: BWS

Beam-column calculation using DSM results for beam and columns (ASD Format)

Notes:

Required allowable strength (ASD demands)

P= 5 kip
M= 3 kip-in

Compression nominal strength and safety factor

Pn = 54.39502 kip
Wc = 1.8
for the interaction equation the fully braced compressive capacity, P no, is needed
this is found by setting Pne=Py and re-calcualting the "column" worksheet.
lℓ = 1.41
Pnℓo = 67.17 kip
Pndo = 55.09 kip
Pno = 55.09 kip

Bending nominal strength and safety factor

Mn = 59.71 kip-in
Wb = 1.67

Factors to account for approximate 2nd order analysis

Cm = 1 see C5.2.1, 1.0 is conservative


PE = 130 kip This is the flexural buckling load about the axis of
bending, it may be found using the Spec. formula of
p2EI/(KL)2 or read directly from a CUFSM analysis
a= 0.931 per Eq. C5.2.1-4 or -5
note, the 2nd order estimate of required allowable strength is 3.22 kip-in

Interaction equations

0.17 0.09 sums to = 0.26 OK <1

0.16 0.08 sums to = 0.25 OK <1

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