seismic anchor bolt design
seismic anchor bolt design
(OP)
Given the SCDOT Seismic Specification loading requirement of designing the connection between the superstructure and the substructure for a lateral load equal to 20% of the dead load reaction in the restrained directions, do you apply the lateral load at the interface between the superstructure and the substructure?
If the lateral load is the result of the inertia of the superstructure when the substructure displaces under seismic loading, I see room to argue that the lateral load should be applied at the center of gravity of the superstructure instead of at the interface. The vertical eccentricity of this lateral load would affect the anchor bolt design loading by creating a couple between the anchor bolts on either side of the beam base plate.
Thanks.
If the lateral load is the result of the inertia of the superstructure when the substructure displaces under seismic loading, I see room to argue that the lateral load should be applied at the center of gravity of the superstructure instead of at the interface. The vertical eccentricity of this lateral load would affect the anchor bolt design loading by creating a couple between the anchor bolts on either side of the beam base plate.
Thanks.





RE: seismic anchor bolt design
My guess is that the rule-of-thumb you are talking about is to protect against shear failure at the interface (sudden and possibly catastrophic), bending failure on the other hand is more ductile and is likely addressed elsewhere in your code, as should many other required analyses and less simplified loading conditions.
Overall you don't really sound like you know what your doing, better get some help.
RE: seismic anchor bolt design
RE: seismic anchor bolt design
Reviewing the limits on the response spectra from AASHTO you will note that the coefficient, Cs is limited to 0.25. Thus it's no wonder that you'd be conservative in using this value times the reaction at the bearing.
I've never seen this value applied at the c.g. Assuming that positive connections are required vertically, the moment resulting from that eccentricity would be resisted by the abutment/pile or bent. Generally speaking these systems are large enough to do that. Thus the lateral load simply would be moved down from the c.g. to the bearing.
Regards,
Regards,
Regards,

Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
RE: seismic anchor bolt design
Thanks.
RE: seismic anchor bolt design
But don't misunderstand what I've written for a reason not to check it. I think its a good idea to do so and experience this for yourself. I think its a good part of the logic that your working with. Keep up the good work.
Regards,
Regards,

Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.