MOORING DOLPHIN

[ANSIF]

Dear Colleges:

In order to evaluate an admissible lateral load, according to your experience, what could be an allowable lateral displacement for the pile head of a mooring dolphin?. In my case I have 20 m depth of water.

Thanks for your comments.

 

[COEngineeer]

Try forum321

 

[BigHarvey]

For large ships it's common to have values between 0.5 m and 1 m
The design of your dolphin depends on the size of the ship , soil resistance profile and water depth. 20 m of water depth is quite high and will influence a lot on the design

 

[ANSIF]

Thanks BigHarvey

Well, this is really a big lateral displacement. I was expecting a shorter value. Let me tell you, I am using the AllPile program and evaluating the behavior of 56 and 60” Ø steel open pipes for a mooring dolphin.

I read this from R. L. Mokwa and I quote “…Pile Displacement: Group efficiency is independent of pile displacement; however, it appears that Ge first decreases as displacement increases, and then becomes constant at deflections in excess of 0.05D (5 % of the pile diameter). The small variations in Ge at deflections greater than 0.05D fall within the typical range of experimental data scatter, and are insignificant with respect to practical design considerations.”

According to this I suppose that maybe to limit the lateral displacement of no more than 5% of the pile diameter could be a good value. What do you think?

 

[ANSIF]

Thanks CoEngineer, but there in not a post or thread about "lateral load" in piles.

 

[BigHarvey]

In France we generally use monopiles for dolphins and very rarely groups of piles.Generally we use a variable inertia over the length of the dolphin in order to have the top part a lot more flexible than the embedded part.
We have two types of dolphins : mooring and accosting. For accosting dolphins you need a lot of flexibility to absorb the shock of the ship. For commercial ships you have generally movements of 70 cm when the ship is accosting with dolphins which are 1.4 m diameter and 30 mm WT at the top. You need this flexibility if you don't want to damage the boat. Part of the total displacement is taken by the rubber defense and part by the pile itself.
For mooring dolphins all the displacement is taken by the pile.
5% of pile diameter seems very little to me unless you are talking about leisure boats of small size.

 

[csd72]

I am just worried about the poor dolphin that you people want to tie to a ship.

Save the dolphins...

 

[BigHarvey]

That's fine with me , we call them "Duc d'Albe" ( Duque de Alba in spanish ! )

 

[ANSIF]

Thanks BigHarvery, and I apology because I gave you a wrong idea of my question. I really meant the use of platforms consisted of an isolated concrete deck (cap) supported on concrete or steel piling. This platform is used as a mooring structure (mooring platform) and is not
designed to withstand the impact of berthing. In my case, the mooring platform is designed to behave in a rigid manner, where the structure consists of a concrete deck (cap) supported by vertical steel piles. In this structure is where I want to estimate an admissible horizontal displacement of the pile fixed head.

And yes csd72, save de dolphins!.