node local coordinate system
Question:
Answer:
Hi,
Dear sir,
Refer to the model attached.
I defined the nodal local coordinate system at the abutment supports such that it lines up with the bridge skew.
I then defined the restraints at these nodes to be free in local x.
When I ran the analysis, I see some reaction in local x, say, under "testing lateral load". How could this be possible?
thanks
Answer:
Hi,
It is happening because of numerical error caused by huge modulus of elasticity of material "4: Rigid". It is 2e+15 kN/m2. Usually, it is rigid enough if you define 1000 times of normal modulus of elasticity. For example, the modulus of elasticity for Conc C30 is 2.497e+7 kN/m2. Then, 2e+10 kN/m2 would be sufficient to represent rigid material property and also it can avoid the numerical error.
After the change above, I can see zero reactions in the local x direction as shown below.
Regards,
DK Lee
Files | ||
---|---|---|
Model 3.mcb 381 KB |
||
DataImage2.jpeg 182 KB |
||
DataImage93.jpeg 40 KB |