Hi,everyone.
I'm an enginner in China, Staad is my favorite program. Recently I design the OVERHEAD TRANSMISSION TOWER, and I want to use STAAD to design it ,because STAAD has the code ASCE 10-97 to Check.
STAAD 20.07.09.31 SS4
In my using the code check, I found some problems:
1. I give members ELA1,ELA3,ELA4, but it seems that it has no use in calculating the KL/r. I also give members KZ,KY, it seems that the KL/r is from KZ*Length/rz, or KY*Length/ry, whereas ELA is no use in the calculation.
Let me take an example, I have a member as in this fig.
330-331,beam no.=300,length = 1133.61, L50*50*4,rz = 9.9mm,L/rz=1133.61/9.9=114.51
I give this member KZ =1, We can see KL/R = 114.51. But I also give this member ELA = 4, which means I also want it to calculate the KL/R by EQN.3.7-7 in ASCE 10-97. According to EQN.3.7-7, KL/R = 60+0.5*L/R = 60+0.5*114.51 = 117.255. Unfortunately, Staad didn't calculate it in this way. ELB has the same problem.
I think, KZ that I give to the member is not the K in EQN.3.7-7, which means EQN3.7-7,KL/R = 60+0.5*L/R = 60+0.5*KZ*L/R. Because we don't put redundant member in model, sometimes leg member is probably divided by the redundant member into 2 or 3 segments, that means the KZ or KY for LEG member is 0.5 or 0.333.
2. It seems the angel steel in STAAD only has 2 axis, one is Z, the major axis, the other is Y, which is the symmetry of the Angle, but the problem is, we don't use the Y axis, we use another axis that parallel to the leg of an angel steel. It cause the result from the calculation is wrong.
3.DBL, NSF, NHL.
Is NSF neccessary? Can STAAD calculate the NSF according to DBL & NHL?
In our design, the owner demands the same diameter of the bolt in whole tower, so I give the DBL a certain value applied on all the member. We also determine that the LEG member's NHL = 2, other comprssion members' NHL = 1. I don't give the NSF, was I wrong
4.Could I have the detail calculation of the results? Take the fig.above as an example, I really don't understand how I can get 0.068, and TENS.CAP,COMP.CAP,BOLT CAP,PA,MAY,MAZ,VY,VZ, What does this mean? And how to get these values?
5.THE UNIT, Why here is KIP,INCH? I have changed the unit to kN&m.
6.ASCE 10-97 parameters, SSY,SSZ,UNB,UNT, I just don't understand this, do you have more detail direciton or instruction of this? Just an example would do good to me, thank you!