I remember a ship loader being designed around some existing rail mounted trucks. The stability calculations were a bit laboured checking different boom positions and wind directions (luckily not in an earthquake zone). For stability it was necessary to add extra ballast in the appropriate areas. ■

Dear Talia,

Pneumatic shipunloaders have my special attention because I have worked, designed and built pneumatic ship unloaders since 1978.

First of all, it seems to me that a shipunloader, which has negative corner loads under the specified working and storing conditions, is not appropriately designed.

You do not mention the type of unloader, whether it is a grain unloader or a cement unloader or other type.

My approach for calculating the corner loads of a specific pneumatic unloader is as follows:

1)

Determine the dead loads at each corner from the weight-location matrix

2)

Determine the corner loads from the live loads, s.a stored unloaded material on the unloader.

3)

Determine the corner loads from the swiveling unloader arm moment at any swivel angle and then determine the most unfavorable position.

4)

Apply the wind forces (working- and storm under stored position) from the most unfavorable direction in the most unfavorable situation and determine the corner loads under these conditions.

If required including wind gusts with a dynamic factor

5)

Apply the earthquake movements in the most unfavorable situation and direction and determine the resulting corner loads with dynamic factor of 2 (dynamic factor)

The center of gravity of the unit must then be known

6)

Combine all the found corner loads into various acceptable combinations.

(f.i. A storm load in working position together with an earth quake is not likely, because the unloader should then be in the stored position, eventually with tie downs to prevent the unit from breaking through the brakes).

7)

If necessary, determine changes to the design or additional counter weight.

This issue is not to be neglected, as it is safety related.

That is why most local authorities require the calculations according the local regulations

I have an old spreadsheet to calculate 1) and 2) an 3)

Success

Teus ■

Dear Talia,

Kovako unloaders are mainly designed for cement.

Is your unloader a new- or a used one?

Have you asked the supplier for more information?

The building Nr of the unit is the code to the files.

The spreadsheet is a difficult one to use with many manual fixes, which easily can lead to unwanted errors.

Have a nice day

Teus ■

Hello Talia

I can't see where your machine is to be located. However, more than likely, it is appropriate to apply the international standard ISO5049.1 to it. This standards is one that describes design requirements for machines for the continuous handling of bulk materials, including the combinations, combinations factors and combination safety factors to be applied for stability. It also provides guidance on the methods for calculating stability.

Though this standard is not so well known in the United States, and it may not even be typically applied to pneumatic machines, it will provide you with invaluable insights on how to treat such machines from a design perspective and on how to prepare your calculation. Look for the table listing the various load cases, their combinations and factors. ■

Originally Posted by FLeng

Would you happen to have a copy of those calcs? That would help me greatly. My email address is talia.garcia@mail.mcgill.ca

Thanks again for your help.

I find these were stored in the basement which was subject to a storm flood of three feet of water. They are no more, sorry. ■

Originally Posted by Teus Tuinenburg

Dear Talia,

Pneumatic shipunloaders have my special attention because I have worked, designed and built pneumatic ship unloaders since 1978.

First of all, it seems to me that a shipunloader, which has negative corner loads under the specified working and storing conditions, is not appropriately designed.

You do not mention the type of unloader, whether it is a grain unloader or a cement unloader or other type.

My approach for calculating the corner loads of a specific pneumatic unloader is as follows:

1)

Determine the dead loads at each corner from the weight-location matrix

2)

Determine the corner loads from the live loads, s.a stored unloaded material on the unloader.

3)

Determine the corner loads from the swiveling unloader arm moment at any swivel angle and then determine the most unfavorable position.

4)

Apply the wind forces (working- and storm under stored position) from the most unfavorable direction in the most unfavorable situation and determine the corner loads under these conditions.

If required including wind gusts with a dynamic factor

5)

Apply the earthquake movements in the most unfavorable situation and direction and determine the resulting corner loads with dynamic factor of 2 (dynamic factor)

The center of gravity of the unit must then be known

6)

Combine all the found corner loads into various acceptable combinations.

(f.i. A storm load in working position together with an earth quake is not likely, because the unloader should then be in the stored position, eventually with tie downs to prevent the unit from breaking through the brakes).

7)

If necessary, determine changes to the design or additional counter weight.

This issue is not to be neglected, as it is safety related.

That is why most local authorities require the calculations according the local regulations

I have an old spreadsheet to calculate 1) and 2) an 3)

Success

Teus

Dear Mr Teus

I have been interacting with you for many other subjects and found very useful response

May i request you to forward the spreadsheet of stability calculation in my below mail id?

chaubey.07@gmail.com ■

Originally Posted by Teus Tuinenburg

Dear Talia,

Pneumatic shipunloaders have my special attention because I have worked, designed and built pneumatic ship unloaders since 1978.

First of all, it seems to me that a shipunloader, which has negative corner loads under the specified working and storing conditions, is not appropriately designed.

You do not mention the type of unloader, whether it is a grain unloader or a cement unloader or other type.

My approach for calculating the corner loads of a specific pneumatic unloader is as follows:

1)

Determine the dead loads at each corner from the weight-location matrix

2)

Determine the corner loads from the live loads, s.a stored unloaded material on the unloader.

3)

Determine the corner loads from the swiveling unloader arm moment at any swivel angle and then determine the most unfavorable position.

4)

Apply the wind forces (working- and storm under stored position) from the most unfavorable direction in the most unfavorable situation and determine the corner loads under these conditions.

If required including wind gusts with a dynamic factor

5)

Apply the earthquake movements in the most unfavorable situation and direction and determine the resulting corner loads with dynamic factor of 2 (dynamic factor)

The center of gravity of the unit must then be known

6)

Combine all the found corner loads into various acceptable combinations.

(f.i. A storm load in working position together with an earth quake is not likely, because the unloader should then be in the stored position, eventually with tie downs to prevent the unit from breaking through the brakes).

7)

If necessary, determine changes to the design or additional counter weight.

This issue is not to be neglected, as it is safety related.

That is why most local authorities require the calculations according the local regulations

I have an old spreadsheet to calculate 1) and 2) an 3)

Success

Teus

Dear Mr Teus Tuinenburg

Sir , in ship unloader , how to calculate earthquake load ? May please explain

thanks in anticipation ■

Dear Guddu,

Apply the seismic loads, based on the earth quake amplitude and frequency (or period) and calculate the response of the structure in combination with the response of the jetty.

Then, these loads are the basis for the stress calculations of the structure, due to an earth quake.

A job for an expert.

Take care

Teus ■

Originally Posted by Teus Tuinenburg

Dear Guddu,

Apply the seismic loads, based on the earth quake amplitude and frequency (or period) and calculate the response of the structure in combination with the response of the jetty.

Then, these loads are the basis for the stress calculations of the structure, due to an earth quake.

A job for an expert.

Take care

Teus

Dear Teus sir

Apparently , ship unloader being designed to be mounting on jetty

Generally we use to calculate "base shear" force considering importance factor, seismic factor . Now what shall be structural action to be taken care for making design against the shear force?

My clarification is , how to calculate seismic force & what is the measures to be ensure to withstand against earthquake ■

Originally Posted by Teus Tuinenburg

Dear Guddu,

Apply the seismic loads, based on the earth quake amplitude and frequency (or period) and calculate the response of the structure in combination with the response of the jetty.

Then, these loads are the basis for the stress calculations of the structure, due to an earth quake.

A job for an expert.

Take care

Teus

Dear Teus sir

In my project , iam employing level luffing crane to unload coal . Vendor has submitted the wheel load drawing . Out of four corner , at one corner there is negative load . My question is , in such case is the machine can be considered stable (as negative load is only at one corner) or not?

This negative load is in case of seismic condition with wind speed 20m/s & coal load

Your immediate reply is highly appreciated ■