[CAUT] pre-stretching new string?

[John Delacour]

At 6:38 am -0500 6/6/07, Ron Nossaman wrote:

>Do they go out every year and tighten the cables of suspension 
>bridges every year to pull the roadway back up level? Anyone know?

Probably not, because

At 7:51 am +0100 1/5/07, John Delacour wrote:

>>...an experiment by Vicat:- " He found that wires held stretched, 
>>with a tension equal to one quarter of the breaking stress, 
>>retained the length to which this tension brought them throughout 
>>the whole time of his experiments (33 months) , while similar wires 
>>stretched with a tension equal to half the breaking stress, 
>>exhibited a notable gradual increase of extension."

Vicat was a pioneer of suspension bridges and carried out these 
experiments in the 1830s with the express purpose of avoiding the 
inconvenience.

The piano string is subject to strains normally far in excess of a 
quarter of the breaking strain and will therefore "exhibit a gradual 
increase in extension".

Of course Vicat lived and worked in France and you can't expect the 
same physical laws to apply in Kansas or Ougadougou.

JD