4/12 NAIL-GLUED ROOF TRUSS - Design and Performance Data - Structural Design Data

Oct 24, 2026

Upload by James

4/12 nail-glued roof truss design and performance data, emphasizing that graphical analysis methods are unreliable for determining stress in nail-glued trusses. The document bases the design on full-scale testing results for two truss types (load-and-recovery and load-to-destruction). Load-to-recovery procedures apply dead load, increment live load, record deflection, remove live load, and measure residual set. Load-to-destruction applies load until failure, reporting an average failure load of about 115 psf with failure in 2x4 chord members and no observed glue-line connection failures.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages1

Reading Time3 min

AccessFree to download

Design and Performance Data

Structural Design Data

Actual Test Data

Actual Test Procedure (Load-and-Recovery and Load-to-Destruction)

Design Data (Span, Slope, Loads)

Material and Member Cutting Schedule

Construct Jig

| 4/12 NAIL-GLUED ROOF TRUSS
2'ON CENTER,29-0”TO 34'-8”SPANS | | | | | | DESIGN AND PERFORMANCE DATA
STRUCTURAL DESIGN DATA
The graphical methods of analysis are unreliable in
calculating stres in the nail-glucd truss.They do not
consider the combined stresses due to secondary bend
ing causod by the extreme rigidity of the nail-glued
joint This truss design is based upon full-scale test
results Two trsts were performed:foad and recovery;
and load-to-destruction.
For the load-and-reoovery test,each of three trusss
were positiuned in a hydraulic testing facility with the
eylinders applying kads at ane-foot intervals along the
top chords.
An initial load of 10 pounds per square foot,repre-
senting the dead load,was applied before beginning de
fection readings.Live loads were applind in inerements
of 10 pounds per square foot and defiection readings
were taken along the bottom chords of the trusses.
Aftcr each incrcnent was applicd,the entire live load
was Temoved and the residuzl deflections reoorded.
After renoval of the design live losd of 30 pounds per
sguare foot,the residual deflection averaged 003 inches.
The lads were increased until a live loadl of 100 pounds
per square foot was reoorded.
For the load-to-destruction test,koad was appliod to
the truss until failare occurred.An average failure
load,for three trusses,was Tecorded at 115 pf.
Failure oocurred in the2x4 chord members at vari
ous locations.No glue-line connection failures were
obscrved.
DESICN DATA
Span:29-0"to 34-8"
Slope:4/12
tet
Dead Load
rb
Live Load
Total
peunds
ACTUAL TEST DATA
(average of 3 trusscs)
LIVE LOAD
0.42"
Deflection at 30 psf.live koad
Average residual set after rdease of
30 psl.
0.010
Average residual set after release of
0.18
100 psf.
115psf
TOTALLOAD at Failure
DERECNON fincha | | --- | --- | --- | --- | --- | --- | --- | | TOP CHORD5-
LDNO DIAGONAL一
PLAR GUssTS
TOP CHOIDS
TOP CHORD SPLCE-
SHORT DLAO0NAL-
BOTTOM CHORDS-
8OTOM CHORns
HEEL GUs5E75
LONO BNAGONAL
SHOET DIAGONAL
KING POST
KING PO5T
All GUsseTS BOTH SIDE
BOHoM CHOBD SPuCr
MIDSPAN OUSSET5
4 HEEL Gu55ETS
4 TOP CORD 5TAPLES
3 PEAK GUS5ET548o11OM CHO02 RJDPAN
SPUCE GUSSETS
0U5SETS
o NAILS
SPLICt Gusszrs | | | | | 1
MEASURE SPAN
Detemine the span(out-to-out diuensioe of
csnerior wall platex)and abo the amount of
overhang desired.
WALL PLATE- | | | 2
ORDER MATERIAL
33'
34'
30'
31'
32'
29'
SPAN
0”
4”
8”
4”
8"
8"
0”4”8”
0“4”8"0"4”
8"
0”4”
0~
Twe2x4x8'-0"
2x4x14'-0"
TWO TOP CHORDSt
Twe 2x4x12'-0*
Two 2x4x10.0*
Two 2×4x10'-0"
BOTTOM CHORD+
2x4
2x4x14'-0"
2x4x12'-0"
2x4x10-0"
x16/-0
TWO 5HORT DIAGONALS
Twe 2x4x12'-0~
Two 2x4x10'-0"
TWo LONG DIAGONAL5
2x4x5'-0"
KING POST
%“x4x8'Plywood—structural interior*
GUSSETS
GLUE
21b.Glue (See Block 100
FASTENERS
2886d ncils or 3841%"power-driven fasteners
1o " “ w id u dn 12 d 1 p rst
nred fanicaied n alagi 7mded or Ie s | | | 3
CUT MEMBERS ACCORDING TO THIS SCHEDULE ICut one pattern fruss frst.)
32′
30′
37'
29'
33'
34'
SPAN
4”
4”
4”
0"
0"
8"
8”
4"
4"
4"
8"
0"
8"
8"
0"
0"
8"
0
7'-0"
8'-0"
"A"
TOP CHORD5
“B”
Cut Only IF Less Overhang Than Thet Lised in Irem "O"Is Desired.
Twe-10-0”Uneut Lengths
"C"
BOTTOM CHORD

FAQs

Why are graphical analysis methods considered unreliable for nail-glued trusses?

They do not account for combined stresses caused by secondary bending resulting from the extreme rigidity of the nail-glued joint.

How is the load-and-recovery test performed and what is measured?

An initial dead load is applied, live load is increased in increments while deflection is recorded along the bottom chords, then the live load is removed and residual deflections (residual set) are recorded.

Where did failure occur in the load-to-destruction test, and were glue-line connection failures observed?

Failure occurred in the 2x4 chord members at various locations, and no glue-line connection failures were observed.

Oct 24, 2026

Upload by James