Structural Timber

Design Group Project

Group 1

Manoj Kandel

Haroon Rasheed Ahmed

Sanjay Tamrakar

Santosh Timilsina

Design Criteria

Facility Type: Residential Building

Location : Arlington, TX

Floor: One Storey

Plan Area: 12ft x 20ft ( Two Rooms)

Wood used: Southern Pine

Building Height: 13 ft

Eaves Height: 3ft

Floor Height: 10 ft

Location Map

Plan and Layout

Load Calculations

Dead load for Residential

building

Asphalt Shingle roof and light

weight tile: 21 psf

Live Load

Roof Live Load: 20 psf

Snow Load: 1.23 psf

Wind Load = 24.46 psf

Wind load on the windward sloped roof

( Downward) =16.63 psf

Calculations based on ASCE 7-10

Modeling

The 3D model of the

structure was done in

SketchUp 3D

Load Combinations

Load Combination Load( psf) Cd Load/CdCritical load

(psf)

D 21 0.9 23.33333

32.8 psf

D+L 21 0.9 23.33333

D+Lr 41 1.25 32.8

D+S 22.23 1.15 19.33043

D+0.75L+0.75Lr 36 1.25 28.8

D+0.75L+0.75S 21.93 1.15 19.06957

D+0.6W 30.98 1.6 19.3625

D+0.75L+0.75(0.6W)+0.75Lr 43.48 1.6 27.175

D+0.75L+0.75(0.6W)+0.75S 29.4 1.6 18.375

D+0.75L+0.75(0.7E)+0.75S 21.92 1.15 19.06087

0.6D+0.6W 22.58 1.6 14.1125

0.6D+0.7E 12.6 0.9 14

ASD Adjustment Factors

Load Duration Factor CD 1.25

Wet Service Factor CM 1

Temperature factor Ct 1

Beam Stability Factor CL 1

Size Factor CF depends on size

Flat Use Factor Cfu 1

Incising factor Ci 1

Repettitive Member factor Cr 1

Column Stability factor Cp 0.211

Buckling Stiffness Factor CT 1

Bearing Area factor Cb 1

Truss Design

Tension Member Design

Dead Load: 21 psf

Roof Live Load: 20 psf

Wind load: 16.63 psf

Most critical combination was D+Lr

Critical Load: 32.8 psf

Truss spaced at 4 ft.

Tension force: 0.6 kips

The member No. 2- Southern Pine 2’’ x

3’’ was found suitable for the tension

force

Compression Member Design

Dead Load: 21 psf

Roof Live Load: 20 psf

Wind load: 16.63 psf

Most critical combination was D+Lr

Critical Load: 32.8 psf

Truss spaced at 4 ft.

Most Critical Compression force: 0.85 kips

The member No. 2- Southern Pine 2’’ x 3’’

was found suitable for the compresssion

force

Beam Design

Designed according NDS provisions( ASD Method)

Beam Length: 10ft

No. 2 Southern Pine

Design for Flexure

Actual Bending Stress: 775.4 psi

Allowable bending stress: 1443.75 psi Bending OK

Design for Shear

Actual Shear Stress: 59.76 psi

Allowable shear Stress: 240.625 psi Shear OK

Check for Deflection

Allowable deflection: 0.5 in

Actual deflection: 0.078 in Deflection OK

Beam Size selected 4’’ x 10’’

Column Design

Reference design value( Compressive stress) Fc= 1450 psi

Column Length: 10 ft

Designed as a fixed- hinged column ke= 0.8

No. 2 Southern Pine

Axial compressive force in the end column: 1332 lb

Axial compressive force in the middle column: 2664 lb

Axial capacity of the column 4” X 4” = 6457.93 lb

USE COLUMN 4” x 4” SIZE

Panel Design

2’’ framing members spaced at 24’’

Total design load: 41 lb/ft

3 ply Panels selected with span rating 24/16

Design for Flexure:

Max Bending moment: 196 lbin

Panel Bending strength FbS’: 400 lbin/ ft of panel width Bending OK

Design for shear

Maximum Shear: 46.125 lb

Panel Shear through the thickness FvTv ‘: 71.25 lb Shear OK

Design for deflection

Allowable deflection: 0.095 in

Actual deflection: 0.0732 in Deflection OK

USE 3 ply Panels of thickness 7/16 inches

Wind Load Design

ASCE 7-10, Wind Speed 115 mph, Exposure category B

Wind Pressure 24.46 psf

Uniform Wind load of 220.14 lb/ft at roof.

Diaphragm dimension= 20 X 12

Designed based on SDPWS

Diaphragm and Shear Wall design with Chord member design and Deflection check

Diaphragm Design

Reaction at ends = R = 2201.4 lb

Shear at Diaphragm = v= 183.45 plf

Tension = Compression in Chord = 5504 lb

Selected wood structural panel using table 4.2A designed as

Blocked from SDPWS.

Selected 5/16” nominal panel thickness of structural grade 1.

6d nail size with nail spacing at diaphragm and nail spacing at

other panel edges to be 6in.

From Table 4.2A, Allowable shear = 295 plf > Shear at

Diaphragm = v= 183.45 plf. OK

Chord Design

Max moment= 11007 lb-ft.

Tension = Compression in Chord = 5504 lb

Assume two No 2, 2X6 Southern Pine dimensional lumber as chord members

Allowable Tension = 10890 lb > 5504 lb, OK

Allowable Compression = 7474 lb > 5504 lb, OK

Deflection Checked as per 4.2.2 of SDPWS

Calculated deflection = 0.176 < Allowable deflection = .45in, OK

Shear Wall Design

Unit Shear at Shear wall= v= 183.45 plf

Designed as per Section 4.3 for SDPWS.

Shear wall in N-S direction does not have any opening in our

case.

Selected wood structural panel using table 4.3A Wood Based

panels from SDPWS.

Used 5/16” nominal panel thickness- Structural 1 grade.

6d nail size and, min fastener penetration in framing member

to be 1-1/4 with panel edge fastener spacing to be 6 in.

Allowable shear = 280 plf > Shear at Diaphragm = v= 183.45

plf. OK

Shear Wall Design

Moment at base= 33021 lb-ft.

Tension = Compression in Chord = 2751 lb

Assume No 2, 2X6 Southern Pine dimensional lumber as chord members

Allowable Tension = 10890 lb > 2751 lb, OK

Allowable Compression = 3835 lb > 2751 lb, OK

Deflection Checked as per 4.3.2 of SDPWS

Calculated deflection = 0.41 < Allowable deflection = .45in, OK

Questions ?