Timber CVB105

Formula for design strength

Design strength = (characteristic strength x modification factors)/partial material factor

what is a ULS check for timber?

if design stress > applied stress then it passes

how to classify different strength classes of timber?

• a letter followed by a number e.g. C14

• C is for soft wood (coniferous)

• D is for hardwood ( deciduous)

• GL is for glulam

• the higher the number the stronger it is

What is the moisture content formula for timber?

MC = mH20/mdry or u% = (mu- mdry)/mdry

U% = moisture content percentage

mu = mass of woof at moisture content u

What is the correlation between moisture content of timber and strength?

the lower the moisture content e.g. 10% the stronger it is. However at 30% MC and onwards, the strength will plateau and stay the same even as the MC increases.

what is a formula used to show that bending stress decreases as loading time increases aka a formula for stress level.

f = 90.4 - 6.3log10t

f = stress level percentage

t = effective duration of the load in hours

formula for calculation of design bending strength

fm,d = design bending strength

fm,k = characteristic bending strength

kmod = modification factor

kh = depth or strength factor

ksys = system strength factor

kcrit = factor for lateral torsional buckling

γM = partial safety factor