Design with a difference - WoodSolutions€¦ · Specification vs Availability –Beam/Lintel Design AFZAL LAPHIR –Principal Engineer, Meyer Timber Pty Ltd . Specification vs Availability

Design with a difference

6 August 2019

AFZAL LAPHIRPrincipal Engineer, Meyer Timber

WoodSolutions Seminar – Structural Solutions for Timber – Adelaide – 6 August 2019

What we will discuss

• Engineered timbers – LVL and GLT

• Myths and facts about MoE or “E”• Member design – property that matters.• Design to limit damage – consider variability in MoE.

• Specification vs availability• Beam/Lintels – can the timber be sourced?• Continuous Spans – is the timber long enough?• Sheet bracing – looking beyond AS 1684

WoodSolutions Seminar – Structural Solutions for Timber – Adelaide – 6 August 2019 AFZAL LAPHIR – Principal Engineer, Meyer Timber Pty Ltd

Meyer Timber

• Mel and Marilyn Meyer established Meyer Timber Pty Ltd in 1975 in Dandenong, Victoria.

• Meyer Timber has now become one of the largest timber wholesale operations in Australia and continues to grow.

Our success is measured by thequality of our customer service.To support this we:

• invest heavily in inventory;through both sheer volumeof product and the diverserange we keep.

• aim to offer fast lead times,so we have createdinfrastructure that has beendesigned for efficienthandling and distribution ofproduct.


We also invest to ensure ourproducts are innovative and ofthe highest quality.

From an industry perspective,we play a significant role inpromoting the use of timber indomestic and mid-riseconstruction.

Meyer Timber

• Mel and Marilyn Meyer established Meyer Timber Pty Ltd in 1975 in Dandenong, Victoria.

• Meyer Timber has now become one of the largest timber wholesale operations in Australia and continues to grow.

• Grown to become not just a timber wholesaler, but also a complete solutions provider.

• Operating in VIC, NSW, QLD and TAS.


Meyer Timber – how we support the timber industry

• A major sponsor of the Mid-Rise Advisory Partnership (MAP).

• Silver sponsor of the Frame & Truss Manufacturer’s Association (FTMA).

• Contribute to education and training through industry forums.

• Offer a range of quality timber products, backed by excellent technical support.


LVL (Laminated Veneer Lumber)

• Developed in 1970s.

• Cost-effective and sustainable material.

• High structural reliability and strength.

• Available in straight, long lengths.Manufactured by bonding together rotary peeled thin wood veneers under heat and pressure.


LVL supplyLVL Grades

• E9

• E11

• E12

• E13

• E14 (F17)

• E15

• E16

• E19

Australia has multiple E13 and E14(F17) supply points but minimal high E suppliers.

• Around 90% of LVLs available in Australia are imported from NZ, US, Europe or China

• Average world E value around 13,000 MPa.

• High E requires Low E for fibre balance.

LVL Suppliers


GLT (Glue Laminated Timber)

• Glulam originated in Germany around 1900. Made its way to Australia in the 1950s.

• Larger sizes and longer lengths than LVLs.

• Supplied with pre-cambered or straight.

Manufactured by gluing together pieces of timber, known as laminates. This process produces larger size and longer length members, which can be curved or straight.


GLT supply


• GLT are supplied as cambered (eg: GL18C) or straight (eg:GL18).

• The pre-camber radius is 600m (i.e 7.5mm camber for 6m lengths or 13mm camber for 8m lengths).

AFZAL LAPHIR – Principal Engineer, Meyer Timber Pty Ltd


• Engineered timbers – LVL and GLT.

• Myths and facts about MoE or “E”• Member design – property that matters• Design to limit damage – consider variability in MoE


MOE?Is he talking about me?


Member design – Is MoE the property that matters?

Sorry, Moe!I am talking about

Modulus of Elasticity

“strength is essential but otherwise unimportant”- Hardy Cross (1885-1959)

Example: Floor joists (F17)

Serviceability governs design in every scenario.

Strength working to :

- 33% when supporting floor loads only

- 51% when supporting floor + heavy LBW

AFZAL LAPHIR – Principal Engineer, Meyer Timber Pty LtdWoodSolutions Seminar – Structural Solutions for Timber – Adelaide – 6 August 2019

MoE – the property that matters

Example: Rafters (F17)

Serviceability governs design in every scenario.

Strength working to less than 52%

Influence of MoE is not confined to floor joists ………. also applicable to rafters


Example: Rafters (MGP10)

Serviceability governs design except in some continuous spans.

…… and not just for F17, but also for all other timber grades … MGP10 is an exception in some applications.



Example: Rafters (MGP10)

The stiffness/strength ratio for MGP10 is double that of F17

…… MGP10 is weak in strength (bending) in comparison with stiffness (average MoE)



Note: The f’b values for MGP and LVL varies with width, and typically for 90mm sections, they will be higher than the above table values, by as much as 15% .


Design to limit damage

• Cracking/damage to roof cladding, ceiling lining etc

• Cracking of glazing due to in-plane movements.

• Damage to partitions

What are the effects ?


Design to limit damage

• Use of average Modulus of Elasticity (E).

• Generous deflection limits.

• Clearances not specified.

• Carry on effects ignored.

State of Play:

Ref: AS 1720.3 – 2016

Limits for Permanent Action (G):

Roof Beams - Span/300 or max 20mmLintels - Span/300 or max 10mmFloor Beams - Span/300 or max 12mm

Long term creep factors (j2):

MGP, F17, LVL - 2.0Glulam - 1.5

Ref: AS 1720.1 – 2010


Design to limit damage - best results are achieved using LVL

Ref: AS 1720.1 – 2010 Appendix B (Guidelines for Serviceability)

“To avoid damages, an upper-bound estimate of deflection may need to becalculated and appropriate clearances specified for construction”

Rough Estimate of E0.05

Code recommends the use of alower fifth-percentile value of MoE(E0.05) to calculate an upper-boundestimate of deflection.

LVL has the least variation.

• Our LVL QC process has shown thevariation can be as low as 8%.

i.e E0.05/Eavge > 0.90


…… Using E0.05 ensures MoE is the property that matters for all timber, including MGP10


Note: The f’b values for MGP and LVL varies with width, and typically for 90mm sections, they will be higher than the above table values, by as much as 15% .

Design to limit damage - best results are achieved using LVL


How can we give buildersimproved flexibility?

i.e offer better supplychain choices.

• Engineered timbers – LVL and GLT.

• Myths and facts about MoE or “E”• Member design – property that matters• Design to limit damage – consider variability in MoE




• MGP - Table H3.1, AS 1720.1

• F Grades - Table H2.1, AS 1720.1

• GLT - Table 7.1, AS 1720.1

• LVL - Refer Manufacturer

Design Properties


LVL Grades

• E9

• E11

• E12

• E13

• E14 (F17)

• E15

• E16

• E19LVL properties are not standardised.They may vary between manufacturers.

Specification vs Availability – Beam/Lintel Design



Impact of MoE on Performance?


Example – LVL Roof beam

- 3.0m single span, supporting tile roof with RLW 3600mm

• 2/200x45 E13 - 9.4mm deflection

• 2/190x45 F17(E14) – 10.3mm deflection

• 2/190x42 E15 – 10.0mm deflection

Note: For comparison purposes, 2/190x45 E13 (not commonly sourced) gives a 11.0mm deflection.

The difference in deflection is < 1.0mm



Things to Consider when specifying LVLs


Ask ourselves:

• Am I specifying the preferred LVL that the project buildersources?

• To make life simpler, shouldn’t I be specifying a genericLVL, that is easily accessible?

Specification as “equivalent E14 or F17” or “as minimum E13”would give the builder enough options.

Remember:

Australia has multiple E13 and E14(F17) supply points but minimal high E suppliers.

Section sizes may vary between grades and between suppliers.


Specification vs availability

• Member design – can the timber be sourced?

• Continuous Spans – is the timber long enough?

• Sheet Bracing – looking beyond AS 1684

How can we give builders improved flexibility?


Continuous Spans

• MGP10 - 6.0m 290x45

• MGP12 - 6.0m 190x45

• MGP15 - in short supply

• F17 - 4.8m (up to 5.4m) 290x45

• LVL - 12.0m (up to 13.2m) 600x75 (E13)**; 290x45 (E14)

• GLT - 18.0m + 1200x130**

Maximum lengths and sizes of structural timber

** not commonly stocked, and maximum sizes can vary with suppliers


Continuous Spans

Effective Span - when spans are unequal ?

L L L1 = 0.80 L

L 0.9L L1 = 0.825 L

Eff span = L

Eff span = 1.03 L

Deflection = D

Deflection = 1.12 D

Deflection = D For span difference = 10%Eff Span - 3% increaseDeflection - 12% increase

For span difference = 50%Eff Span - 7% increaseDeflection - 32% increase

L 0.5L L1 = 0.86 LEff span = 1.07 LDeflection = 1.32 D

CONTINUOUS SPAN EQUIVALENT SINGLE SPAN


Continuous SpansLength of beam vs Maximum span When designing for continuous spans,

the overall length of beam is asimportant a consideration as themaximum span and the span difference.

For LVL E14 (or E13), the overall lengthcannot exceed 12m.

For longer lengths, design as SINGLEspan.

L L

0.5L1

Example – LVL E14


Max span (L1)

Overall length ≤ 12.0m

Eff span for design = 1.07 L1, when span difference = 50%


Continuous Spans

• Only the values in are applicable.

• Limited use for Continuous Spans,a maximum of 2700mm

• Maximum lengths (F17) that can be sourced is 5400mm.

Example: Design of F17 rafters using AS 1684 span tables


Continuous SpansExample: Design of F17 rafters using AS 1684 span tables

Therefore these span tables are morerelevant to LVL E14 as :

• the property that really matters is theMoE, where MoE(F17) = MoE(LVL E14)

• LVL E14 can be easily sourced instandard F17 sizes (45mm thickness)and up to 12,000mm lengths.


Specification vs availability

• Member design – can the timber be sourced?

• Continuous Spans – is the timber long enough?

• Sheet Bracing – looking beyond AS 1684

How can we give builders improved flexibility?


Sheet Bracing

Light-duty version - 3.4 kN/m

• Plywood - Table 8.18, detail (g)

• Hardboard - Table 8.18, detail (l)

Minimum 900mm wall lengths

Within AS 1684.2


Sheet Bracing

Light-duty version - 3.4 kN/m

• Plywood - Table 8.18, detail (g)

• Hardboard - Table 8.18, detail (l)


• OSB Brace – refer manufacturer’s details (Egger)

Within AS 1684.2

Outside AS 1684.2


Sheet Bracing

Heavy-duty version – 6.0 kN/m

• Plywood - Table 8.18, detail (h)

• Hardboard - Table 8.18, detail (m)


Within AS 1684.2


Sheet Bracing

Heavy-duty version – 6.0 kN/m

• Plywood - Table 8.18, detail (h)

• Hardboard - Table 8.18, detail (m)



Within AS 1684.2

Outside AS 1684.2


Sheet Bracing

Short Wall Brace

• Plywood - Table 8.18, detail (g/h)

• Hardboard - Table 8.18, detail (n)


Within AS 1684.2


Sheet Bracing

Short Wall Brace

• Plywood - Table 8.18, detail (g/h)

• Hardboard - Table 8.18, detail (n)



Within AS 1684.2

Outside AS 1684.2


Sheet Bracing – availability

• Plywood :7mm F8 - available in 900/1200 widths and 2440/2745 lengths.

4mm F22 - available in 900/1200 widths and 2440/2745/3050 lengths.

• Hardboard4.8mm - available in 900/1200 widths and 2440/2745/3050 lengths.

• OSB Brace :

6mm - available in 900/1200 widths and 2440/2745/3050 lengths.

Most common plywood

Most popular sheet brace. Over 70% market share (?)

In short supply


- OSB is more readily available than plywood due to manufacture.- Plywood is made from veneers, leaves peeler cores behind, so needs bigger trees.- OSB manufacture, on the other hand, involves shredding the log and using all of the wood fibre.


Sheet Bracing – why OSB Brace?

from a builder’s perspective ……

• Readily available and price competitive.

• Excellent moisture resistance properties - resists distortion, splitting, delamination and buckling.

• simple to install, being lightweight, easy to cut, nail, screw and drill,

• clean fresh timber appearance, without any of the typical veneer defects of plywood.


• derived from independent testing of full-scale prototype panels at the Central QLD University.

• independently certified by the University of Technology Sydney.

• higher capacities than it’s comparable sheet bracing products.

Sheet Bracing – why OSB Brace?

from a specifier’s perspective ……

3.4 kN/m products:

Unlike plywood and hardboard, Egger OS’Brace has been tested in JD5 framing. Therefore no reduction when used in wall frames with MGP10 material.


Summary

• Specification vs Availability- Specifying a more generic “E14(F17) equivalent” or “minimum E13”

gives builders the best supply chain choices.- F17 span tables (AS 1684) are more suited for LVL E14.

- OS’Brace is a viable alternative to AS 1684 sheet bracing products.


• Engineered timbers- LVL properties are variable and provided by the manufacturer.- Higher ‘E’ values have limited supply.

• Myths and facts about MoE or “E”- MoE is the property that matters.

- But, substituting LVL E14 in place of LVL E15 (or E13 instead of E14)

has little impact on performance (eg: deflection may increase by < 1mm)

- When designing to ‘limit damage’, best results are achieved using LVLs.


Questions?

MT_opener.mp4

Documents

Design with a difference - WoodSolutions€¦ · Specification vs Availability –Beam/Lintel Design AFZAL LAPHIR –Principal Engineer, Meyer Timber Pty Ltd . Specification vs Availability