A very basic question: What is acceleration load?

[zhddz]

When I define a load case in SAP2000, there are two types of load. One is "load pattern", and the other one is "acceleration”.

If I define acceleration in "UZ" direction, with scale factor of 1, what does it mean? The scale factor is the factor of what? Factor of the gravity?

I defined an acceleration load to a cantilever with uniform mass, but I get some concentrate load reactions. I do not understand why.

 

[IJR]

zhddz

If you apply an accelartion load at a node and there is a mass of 5kN at that node, you will get a reaction of 5kN no matter how long your cantilever is

Got the point?.

SAP2000 allows you to convert masses into forces by F=m x a

Good, keep on testing.

respects
IJR

 

[zhddz]

Hello?IJR:

Thank you very much for your response, but I still haven't got the point.

If I have a mass weights 5kN at the tip of a cantilever, I will get 5kN reaction at the base

without acceleration. I do not quite understand you.

Following figures show my cantilever. There are only two Load Cases, DEAD and ACCELERATION.

I did not assign any load to neither load case. The cantilever has selfweight only, and it

is 15m long.

Could some one tell me how the software got the reaction of 0.25kN in Figure 3?

Figure 1. Acceleration Load Case.

Figure 2. Result from Dead Load

Figure 3. Result from Acceleration

 

[IJR]

I will check your models later

but for now, please remove the mass of the beam and put a point mass at the tip.

Then run the model, check the results

It is the mass of the beam that is confusing you. Use one simple mass at the tip

 

[zhddz]

Sorry, the pictures are down. I post them again.

Figure 1. Acceleration Load Case.

Figure 2. Result from Dead Load

Figure 3. Result from Acceleration